# | Rank | Similarity | Title + Abs. | Year | PMID |
|---|---|---|---|---|---|
| 0 | 1 | 2 | 3 | 4 | 5 |
| 1254 | 0 | 0.9536 | Genetic diversity and antimicrobial resistance of Staphylococcus aureus from recurrent tonsillitis in children. The aim of this study was to analyze the prevalence of Staphylococcus aureus in the tonsils of children subjected tonsillectomy due to recurrent tonsilitis and to determine the spa types of the pathogens, carriage of virulence genes and antimicrobial resistance profiles. The study included 73 tonsillectomized children. Bacteria, including S. aureus were isolated from tonsillar surface prior to tonsillectomy, recovered from tonsillar core at the time of the surgery, and from posterior pharynx 2-4 weeks after the procedure. Staphylococcus aureus isolates were compared by spa typing, tested for antimicrobial susceptibility and for the presence of superantigenic toxin genes (sea-seu, eta, etb, tst, lukS/lukF-PV) by multiplex polymerase chain reaction. Seventy-three patients (mean 7.1 ± 4.1 years, 61.6% male) were assessed. The most commonly isolated bacteria were S. aureus. The largest proportion of staphylococcal isolates originated from tonsillar core (63%), followed by tonsillar surface (45.1%) and posterior pharynx in tonsillectomized children (18.2%, p = 0.007). Five (6.3%) isolates were identified as MRSA (mecA-positive). Up to 67.5% of the isolates synthesized penicillinases (blaZ-positive isolates), and 8.8% displayed MLS(B) resistance. The superantigenic toxin genes were detected in more than half of examined isolates (56.3%). spa types t091, t084, and t002, and clonal complexes (CCs) CC7, CC45, and CC30 turned out to be most common. Staphylococcus aureus associated with RT in children showed pathogenicity potential and considerable genetic diversity, and no clones were found to be specific for this condition although further studies are needed. | 2020 | 31692060 |
| 117 | 1 | 0.9527 | Acyl depsipeptide (ADEP) resistance in Streptomyces. ADEP, a molecule of the acyl depsipeptide family, has an antibiotic activity with a unique mode of action. ADEP binding to the ubiquitous protease ClpP alters the structure of the enzyme. Access of protein to the ClpP proteolytic chamber is therefore facilitated and its cohort regulatory ATPases (ClpA, ClpC, ClpX) are not required. The consequent uncontrolled protein degradation in the cell appears to kill the ADEP-treated bacteria. ADEP is produced by Streptomyces hawaiiensis. Most sequenced genomes of Streptomyces have five clpP genes, organized as two distinct bicistronic operons, clpP1clpP2 and clpP3clpP4, and a single clpP5 gene. We investigated whether the different Clp proteases are all sensitive to ADEP. We report that ClpP1 is a target of ADEP whereas ClpP3 is largely insensitive. In wild-type Streptomyces lividans, clpP3clpP4 expression is constitutively repressed and the reason for the maintenance of this operon in Streptomyces has been elusive. ClpP activity is indispensable for survival of actinomycetes; we therefore tested whether the clpP3clpP4 operon, encoding an ADEP-insensitive Clp protease, contributes to a mechanism of ADEP resistance by target substitution. We report that in S. lividans, inactivation of ClpP1ClpP2 production or protease activity is indeed a mode of resistance to ADEP although it is neither the only nor the most frequent mode of resistance. The ABC transporter SclAB (orthologous to the Streptomyces coelicolor multidrug resistance pump SCO4959-SCO4960) is also able to confer ADEP resistance, and analysis of strains with sclAB deletions indicates that there are also other mechanisms of ADEP resistance. | 2011 | 21636652 |
| 59 | 2 | 0.9521 | Plant Ribosomal Proteins, RPL12 and RPL19, Play a Role in Nonhost Disease Resistance against Bacterial Pathogens. Characterizing the molecular mechanism involved in nonhost disease resistance is important to understand the adaptations of plant-pathogen interactions. In this study, virus-induced gene silencing (VIGS)-based forward genetics screen was utilized to identify genes involved in nonhost resistance in Nicotiana benthamiana. Genes encoding ribosomal proteins, RPL12 and RPL19, were identified in the screening. These genes when silenced in N. benthamiana caused a delay in nonhost bacteria induced hypersensitive response (HR) with concurrent increase in nonhost bacterial multiplication. Arabidopsis mutants of AtRPL12 and AtRPL19 also compromised nonhost resistance. The studies on NbRPL12 and NbRPL19 double silenced plants suggested that both RPL12 and RPL19 act in the same pathway to confer nonhost resistance. Our work suggests a role for RPL12 and RPL19 in nonhost disease resistance in N. benthamiana and Arabidopsis. In addition, we show that these genes also play a minor role in basal resistance against virulent pathogens. | 2015 | 26779226 |
| 518 | 3 | 0.9517 | Bacitracin and nisin resistance in Staphylococcus aureus: a novel pathway involving the BraS/BraR two-component system (SA2417/SA2418) and both the BraD/BraE and VraD/VraE ABC transporters. Two-component systems (TCSs) are key regulatory pathways allowing bacteria to adapt their genetic expression to environmental changes. Bacitracin, a cyclic dodecylpeptide antibiotic, binds to undecaprenyl pyrophosphate, the lipid carrier for cell wall precursors, effectively inhibiting peptidoglycan biosynthesis. We have identified a novel and previously uncharacterized TCS in the major human pathogen Staphylococcus aureus that we show to be essential for bacitracin and nisin resistance: the BraS/BraR system (Bacitracin resistance associated; SA2417/SA2418). The braRS genes are located immediately upstream from genes encoding an ABC transporter, accordingly designated BraDE. We have shown that the BraSR/BraDE module is a key bacitracin and nisin resistance determinant in S. aureus. In the presence of low antibiotic concentrations, BraSR activate transcription of two operons encoding ABC transporters: braDE and vraDE. We identified a highly conserved imperfect palindromic sequence upstream from the braDE and vraDE promoter sequences, essential for their transcriptional activation by BraSR, suggesting it is the likely BraR binding site. We demonstrated that the two ABC transporters play distinct and original roles in antibiotic resistance: BraDE is involved in bacitracin sensing and signalling through BraSR, whereas VraDE acts specifically as a detoxification module and is sufficient to confer bacitracin and nisin resistance when produced on its own. We show that these processes require functional BraD and VraD nucleotide-binding domain proteins, and that the large extracellular loop of VraE confers its specificity in bacitracin resistance. This is the first example of a TCS associated with two ABC transporters playing separate roles in signal transduction and antibiotic resistance. | 2011 | 21696458 |
| 556 | 4 | 0.9515 | An ArsR/SmtB family member regulates arsenic resistance genes unusually arranged in Thermus thermophilus HB27. Arsenic resistance is commonly clustered in ars operons in bacteria; main ars operon components encode an arsenate reductase, a membrane extrusion protein, and an As-sensitive transcription factor. In the As-resistant thermophile Thermus thermophilus HB27, genes encoding homologues of these proteins are interspersed in the chromosome. In this article, we show that two adjacent genes, TtsmtB, encoding an ArsR/SmtB transcriptional repressor and, TTC0354, encoding a Zn(2+) /Cd(2+) -dependent membrane ATPase are involved in As resistance; differently from characterized ars operons, the two genes are transcribed from dedicated promoters upstream of their respective genes, whose expression is differentially regulated at transcriptional level. Mutants defective in TtsmtB or TTC0354 are more sensitive to As than the wild type, proving their role in arsenic resistance. Recombinant dimeric TtSmtB binds in vitro to both promoters, but its binding capability decreases upon interaction with arsenate and, less efficiently, with arsenite. In vivo and in vitro experiments also demonstrate that the arsenate reductase (TtArsC) is subjected to regulation by TtSmtB. We propose a model for the regulation of As resistance in T. thermophilus in which TtSmtB is the arsenate sensor responsible for the induction of TtArsC which generates arsenite exported by TTC0354 efflux protein to detoxify cells. | 2017 | 28696001 |
| 9992 | 5 | 0.9513 | Streptococcal Lancefield polysaccharides are critical cell wall determinants for human Group IIA secreted phospholipase A2 to exert its bactericidal effects. Human Group IIA secreted phospholipase A2 (hGIIA) is an acute phase protein with bactericidal activity against Gram-positive bacteria. Infection models in hGIIA transgenic mice have suggested the importance of hGIIA as an innate defense mechanism against the human pathogens Group A Streptococcus (GAS) and Group B Streptococcus (GBS). Compared to other Gram-positive bacteria, GAS is remarkably resistant to hGIIA activity. To identify GAS resistance mechanisms, we exposed a highly saturated GAS M1 transposon library to recombinant hGIIA and compared relative mutant abundance with library input through transposon-sequencing (Tn-seq). Based on transposon prevalence in the output library, we identified nine genes, including dltA and lytR, conferring increased hGIIA susceptibility. In addition, seven genes conferred increased hGIIA resistance, which included two genes, gacH and gacI that are located within the Group A Carbohydrate (GAC) gene cluster. Using GAS 5448 wild-type and the isogenic gacI mutant and gacI-complemented strains, we demonstrate that loss of the GAC N-acetylglucosamine (GlcNAc) side chain in the ΔgacI mutant increases hGIIA resistance approximately 10-fold, a phenotype that is conserved across different GAS serotypes. Increased resistance is associated with delayed penetration of hGIIA through the cell wall. Correspondingly, loss of the Lancefield Group B Carbohydrate (GBC) rendered GBS significantly more resistant to hGIIA-mediated killing. This suggests that the streptococcal Lancefield antigens, which are critical determinants for streptococcal physiology and virulence, are required for the bactericidal enzyme hGIIA to exert its bactericidal function. | 2018 | 30321240 |
| 94 | 6 | 0.9513 | Dominant and Recessive Major R Genes Lead to Different Types of Host Cell Death During Resistance to Xanthomonas oryzae in Rice. The bacterial blight caused by Xanthomonas oryzae pv. oryzae (Xoo) is the most devastating bacterial disease of rice worldwide. A number of dominant major disease resistance (MR) genes and recessive MR genes against Xoo have been cloned and molecularly characterized in the last two decades. However, how these MR genes mediated-resistances occur at the cytological level is largely unknown. Here, by ultrastructural examination of xylem parenchyma cells, we show that resistances to Xoo conferred by dominant MR genes and recessive MR genes resulted in different types of programmed cell death (PCD). Three dominant MR genes Xa1, Xa4, and Xa21 and two recessive MR genes xa5 and xa13 that encode very different proteins were used in this study. We observed that Xa1-, Xa4-, and Xa21-mediated resistances to Xoo were associated mainly with autophagy-like cell death featured by the formation of autophagosome-like bodies in the xylem parenchyma cells. In contrast, the xa5- and xa13-mediated resistances to Xoo were associated mainly with vacuolar-mediated cell death characterized by tonoplast disruption of the xylem parenchyma cells. Application of autophagy inhibitor 3-methyladenine partially compromised Xa1-, Xa4-, and Xa21-mediated resistances, as did Na(2)HPO(4) alkaline solution to xa5- and xa13-mediated resistances. These results suggest that autophagy-like cell death is a feature of the dominant MR gene-mediated resistance to Xoo and vacuolar-mediated cell death is a characteristic of the recessive MR gene-mediated resistance. | 2018 | 30519255 |
| 570 | 7 | 0.9512 | Genetic instability and methylation tolerance in colon cancer. Microsatellite instability was first identified in colon cancer and later shown to be due to mutations in genes responsible for correction of DNA mismatches. Several human mismatch correction genes that are homologous to those of yeast and bacteria have been identified and are mutated in families affected by the hereditary non-polyposis colorectal carcinoma (HNPCC) syndrome. Similar alterations have been also found in some sporadic colorectal cancers. The mismatch repair pathway corrects DNA replication errors and repair-defective colorectal carcinoma cell lines exhibit a generalized mutator phenotype. An additional consequence of mismatch repair defects is cellular resistance, or tolerance, to certain DNA damaging agents. | 1996 | 8967715 |
| 8363 | 8 | 0.9509 | Hundreds of antimicrobial peptides create a selective barrier for insect gut symbionts. The spatial organization of gut microbiota is crucial for the functioning of the gut ecosystem, although the mechanisms that organize gut bacterial communities in microhabitats are only partially understood. The gut of the insect Riptortus pedestris has a characteristic microbiota biogeography with a multispecies community in the anterior midgut and a monospecific bacterial population in the posterior midgut. We show that the posterior midgut region produces massively hundreds of specific antimicrobial peptides (AMPs), the Crypt-specific Cysteine-Rich peptides (CCRs) that have membrane-damaging antimicrobial activity against diverse bacteria but posterior midgut symbionts have elevated resistance. We determined by transposon-sequencing the genetic repertoire in the symbiont Caballeronia insecticola to manage CCR stress, identifying different independent pathways, including AMP-resistance pathways unrelated to known membrane homeostasis functions as well as cell envelope functions. Mutants in the corresponding genes have reduced capacity to colonize the posterior midgut, demonstrating that CCRs create a selective barrier and resistance is crucial in gut symbionts. Moreover, once established in the gut, the bacteria differentiate into a CCR-sensitive state, suggesting a second function of the CCR peptide arsenal in protecting the gut epithelia or mediating metabolic exchanges between the host and the gut symbionts. Our study highlights the evolution of an extreme diverse AMP family that likely contributes to establish and control the gut microbiota. | 2024 | 38865264 |
| 60 | 9 | 0.9508 | Arabidopsis NHO1 is required for general resistance against Pseudomonas bacteria. Nonhost interactions are prevalent between plants and specialized phytopathogens. Although it has great potential for providing crop plants with durable resistance, nonhost resistance is poorly understood. Here, we show that nonhost resistance is controlled, at least in part, by general resistance. Arabidopsis plants are resistant to the nonhost pathogen Pseudomonas syringae pv phaseolicola NPS3121 and completely arrest bacterial multiplication in the plant. Ten Arabidopsis mutants were isolated that were compromised in nonhost (nho) resistance to P. s. phaseolicola. Among these, nho1 is caused by a single recessive mutation that defines a novel gene. nho1 is defective in nonspecific resistance to Pseudomonas bacteria, because it also supported the growth of P. s. tabaci and P. fluorescens bacteria, both of which are nonpathogenic on Arabidopsis. In addition, the nho1 mutation also compromised resistance mediated by RPS2, RPS4, RPS5, and RPM1. Interestingly, the nho1 mutation had no effect on the growth of the virulent bacteria P. s. maculicola ES4326 and P. s. tomato DC3000, but it partially restored the in planta growth of the DC3000 hrpS(-) mutant bacteria. Thus, the virulent bacteria appear to evade or suppress NHO1-mediated resistance by means of an Hrp-dependent virulence mechanism. | 2001 | 11226196 |
| 198 | 10 | 0.9508 | The Drosophila immune defense against gram-negative infection requires the death protein dFADD. Drosophila responds to Gram-negative infections by mounting an immune response that depends on components of the IMD pathway. We recently showed that imd encodes a protein with a death domain with high similarity to that of mammalian RIP. Using a two-hybrid screen in yeast, we have isolated the death protein dFADD as a molecule that associates with IMD. Our data show that loss of dFADD function renders flies highly susceptible to Gram-negative infections without affecting resistance to Gram-positive bacteria. By genetic analysis we show that dFADD acts downstream of IMD in the pathway that controls inducibility of the antibacterial peptide genes. | 2002 | 12433364 |
| 9056 | 11 | 0.9508 | Antibacterial potential of hGlyrichin encoded by a human gene. Emerging multidrug-resistant (MDR) bacteria are an enormous threat to human life because of their resistance to currently available antibiotics. The genes encoding antibacterial peptides have been studied extensively and are excellent candidates for a new generation of antibiotic drugs to fight MDR bacteria. In contrast to traditional antibiotics, antibacterial peptides, which do not cause drug resistance, have an unparalleled advantage. However, because most antibacterial peptides originate in species other than humans, the hetero-immunological rejection of antibacterial peptides is a key disadvantage that limits their clinical application. In this study, we identify hGlyrichin as a potential human antibacterial polypeptide. The hGlyrichin polypeptide kills a variety of bacteria including the MDR bacteria methicillin-resistant Staphylococcus aureus, MDR Pseudomonas aeruginosa, and MDR tubercle bacillus. A 19 amino acid peptide (pCM19) at positions 42-60 of hGlyrichin is crucial for its antibacterial activity. The hGlyrichin polypeptide kills bacteria through the destruction of the bacterial membrane. In addition, all peptides that are homologous to hGlyrichin have antibacterial activity and can penetrate the bacterial membrane. Importantly, hGlyrichin does not cause hemolytic side effects in vitro or in vivo. Therefore, based on the virtues of hGlyrichin, i.e., the absence of hetero-immunological rejection and hemolytic side effects and the unambiguous efficacy of killing pathogenic MDR bacteria, we propose hGlyrichin as a potential human antibacterial polypeptide. | 2012 | 22083756 |
| 118 | 12 | 0.9506 | Trichlorination of a Teicoplanin-Type Glycopeptide Antibiotic by the Halogenase StaI Evades Resistance. Glycopeptide antibiotics (GPAs) include clinically important drugs used for the treatment of infections caused by Gram-positive pathogens. These antibiotics are specialized metabolites produced by several genera of actinomycete bacteria. While many GPAs are highly chemically modified, A47934 is a relatively unadorned GPA lacking sugar or acyl modifications, common to other members of the class, but which is chlorinated at three distinct sites. The biosynthesis of A47934 is encoded by a 68-kb gene cluster in Streptomyces toyocaensis NRRL 15009. The cluster includes all necessary genes for the synthesis of A47934, including two predicted halogenase genes, staI and staK In this study, we report that only one of the halogenase genes, staI, is necessary and essential for A47934 biosynthesis. Chlorination of the A47934 scaffold is important for antibiotic activity, as assessed by binding affinity for the target N-acyl-d-Ala-d-Ala. Surprisingly, chlorination is also vital to avoid activation of enterococcal and Streptomyces VanB-type GPA resistance through induction of resistance genes. Phenotypic assays showed stronger induction of GPA resistance by the dechlorinated compared to the chlorinated GPA. Correspondingly, the relative expression of the enterococcal vanA resistance gene was shown to be increased by the dechlorinated compared to the chlorinated compound. These results provide insight into the biosynthesis of GPAs and the biological function of GPA chlorination for this medically important class of antibiotic. | 2018 | 30275088 |
| 71 | 13 | 0.9506 | How the bacterial plant pathogen Xanthomonas campestris pv. vesicatoria conquers the host. Abstract Xanthomonas campestris pv. vesicatoria (Xcv) is the causal agent of bacterial spot disease on pepper and tomato. Pathogenicity on susceptible plants and the induction of the hypersensitive reaction (HR) on resistant plants requires a number of genes, designated hrp, most of which are clustered in a 23-kb chromosomal region. Nine hrp genes encode components of a type III protein secretion apparatus that is conserved in Gram-negative plant and animal pathogenic bacteria. We have recently demonstrated that Xcv secretes proteins into the culture medium in a hrp-dependent manner. Substrates of the Hrp secretion machinery are pathogenicity factors and avirulence proteins, e.g. AvrBs3. The AvrBs3 protein governs recognition, i.e. HR induction, when bacteria infect pepper plants carrying the corresponding resistance gene Bs3. Intriguingly, the AvrBs3 protein contains eukaryotic signatures such as nuclear localization signals (NLS), and has been shown to act inside the plant cell. We postulate that AvrBs3 is transferred into the plant cell via the Hrp type III pathway and that recognition of AvrBs3 takes place in the plant cell nucleus. | 2000 | 20572953 |
| 747 | 14 | 0.9504 | S51 Family Peptidases Provide Resistance to Peptidyl-Nucleotide Antibiotic McC. Microcin C (McC)-like compounds are natural Trojan horse peptide-nucleotide antibiotics produced by diverse bacteria. The ribosomally synthesized peptide parts of these antibiotics are responsible for their facilitated transport into susceptible cells. Once inside the cell, the peptide part is degraded, releasing the toxic payload, an isoaspartyl-nucleotide that inhibits aspartyl-tRNA synthetase, an enzyme essential for protein synthesis. Bacteria that produce microcin C-like compounds have evolved multiple ways to avoid self-intoxication. Here, we describe a new strategy through the action of S51 family peptidases, which we name MccG. MccG cleaves the toxic isoaspartyl-nucleotide, rendering it inactive. While some MccG homologs are encoded by gene clusters responsible for biosynthesis of McC-like compounds, most are encoded by standalone genes whose products may provide a basal level of resistance to peptide-nucleotide antibiotics in phylogenetically distant bacteria. IMPORTANCE Here, we identified a natural substrate for a major phylogenetic clade of poorly characterized S51 family proteases from bacteria. We show that these proteins can contribute to a basal level of resistance to an important class of natural antibiotics. | 2022 | 35467414 |
| 58 | 15 | 0.9504 | A Conserved Basal Transcription Factor Is Required for the Function of Diverse TAL Effectors in Multiple Plant Hosts. Many Xanthomonas bacteria use transcription activator-like effector (TALE) proteins to activate plant disease susceptibility (S) genes, and this activation contributes to disease. We recently reported that rice basal transcription factor IIA gamma subunit, OsTFIIAγ5, is hijacked by TALE-carrying Xanthomonas oryzae infecting the plants. However, whether TFIIAγs are also involved in TALE-carrying Xanthomonas-caused diseases in other plants is unknown. Here, molecular and genetic approaches were used to investigate the role of TFIIAγs in other plants. We found that TFIIAγs are also used by TALE-carrying Xanthomonas to cause disease in other plants. The TALEs of Xanthomonas citri pv. citri (Xcc) causing canker in citrus and Xanthomonas campestris pv. vesicatoria (Xcv) causing bacterial spot in pepper and tomato interacted with corresponding host TFIIAγs as in rice. Transcriptionally suppressing TFIIAγ led to resistance to Xcc in citrus and Xcv in pepper and tomato. The 39th residue of OsTFIIAγ5 and citrus CsTFIIAγ is vital for TALE-dependent induction of plant S genes. As mutated OsTFIIAγ5(V 39E), CsTFIIAγ(V 39E), pepper CaTFIIAγ(V 39E), and tomato SlTFIIAγ(V 39E) also did not interact with TALEs to prevent disease. These results suggest that TALE-carrying bacteria share a common mechanism for infecting plants. Using TFIIAγ(V 39E)-type mutation could be a general strategy for improving resistance to TALE-carrying pathogens in crops. | 2017 | 29163628 |
| 333 | 16 | 0.9504 | Mutants of Escherichia coli altered in both genes coding for the elongation factor Tu. Genetic analysis of a mutant of Escherichia coli resistant to the antibiotic mocimycin is presented. This resistance is due to alterations in both tuf genes coding for the elongation factor Tu. Mocimycin resistance is recessive. Bacteria carryong only one tuf gene from the resistant mutant are still mocimycin sensitive. If the mutant gene is the tufA gene, the seisitive cells can be made resistant through inactivation of the tufB gene by insertion of the bacteriophage milliunits genome. Conditional mocimycin-resistant mutants ban also be isolated when the tufB gene is altered by an amber or a temperature-sensitive mutation. When only the tufB allele from the original mocimycin-resistant mutant is present, inactivation of the wild-type tufA gene fails to give viable mocimycin-resistant progeny. We conclude that the tufA mutant allele codes for a functional mocimycin-resistant EF-Tu, whereas the mutant tufB gene does not code for a functional product. | 1978 | 360222 |
| 9976 | 17 | 0.9504 | New ΦBT1 site-specific integrative vectors with neutral phenotype in Streptomyces. Integrative plasmids are one of the best options to introduce genes in low copy and in a stable form into bacteria. The ΦC31-derived plasmids constitute the most common integrative vectors used in Streptomyces. They integrate at different positions (attB and pseudo-attB sites) generating different mutations. The less common ΦBT1-derived vectors integrate at the unique attB site localized in the SCO4848 gene (S. coelicolor genome) or their orthologues in other streptomycetes. This work demonstrates that disruption of SCO4848 generates a delay in spore germination. SCO4848 is co-transcribed with SCO4849, and the spore germination phenotype is complemented by SCO4849. Plasmids pNG1-4 were created by modifying the ΦBT1 integrative vector pMS82 by introducing a copy of SCO4849 under the control of the promoter region of SCO4848. pNG2 and pNG4 also included a copy of the P ermE * in order to facilitate gene overexpression. pNG3 and pNG4 harboured a copy of the bla gene (ampicillin resistance) to facilitate selection in E. coli. pNG1-4 are the only integrative vectors designed to produce a neutral phenotype when they are integrated into the Streptomyces genome. The experimental approach developed in this work can be applied to create phenotypically neutral integrative plasmids in other bacteria. | 2016 | 26758297 |
| 8425 | 18 | 0.9504 | Carotenoid biosynthesis in extremophilic Deinococcus-Thermus bacteria. Bacteria from the phylum Deinococcus-Thermus are known for their resistance to extreme stresses including radiation, oxidation, desiccation and high temperature. Cultured Deinococcus-Thermus bacteria are usually red or yellow pigmented because of their ability to synthesize carotenoids. Unique carotenoids found in these bacteria include deinoxanthin from Deinococcus radiodurans and thermozeaxanthins from Thermus thermophilus. Investigations of carotenogenesis will help to understand cellular stress resistance of Deinococcus-Thermus bacteria. Here, we discuss the recent progress toward identifying carotenoids, carotenoid biosynthetic enzymes and pathways in some species of Deinococcus-Thermus extremophiles. In addition, we also discuss the roles of carotenoids in these extreme bacteria. | 2010 | 20832321 |
| 612 | 19 | 0.9503 | Pathways and roles of wall teichoic acid glycosylation in Staphylococcus aureus. The thick peptidoglycan layers of Gram-positive bacteria are connected to polyanionic glycopolymers called wall teichoic acids (WTA). Pathogens such as Staphylococcus aureus, Listeria monocytogenes, or Enterococcus faecalis produce WTA with diverse, usually strain-specific structure. Extensive studies on S. aureus WTA mutants revealed important functions of WTA in cell division, growth, morphogenesis, resistance to antimicrobials, and interaction with host or phages. While most of the S. aureus WTA-biosynthetic genes have been identified it remained unclear for long how and why S. aureus glycosylates WTA with α- or β-linked N-acetylglucosamine (GlcNAc). Only recently the discovery of two WTA glycosyltransferases, TarM and TarS, yielded fundamental insights into the roles of S. aureus WTA glycosylation. Mutants lacking WTA GlcNAc are resistant towards most of the S. aureus phages and, surprisingly, TarS-mediated WTA β-O-GlcNAc modification is essential for β-lactam resistance in methicillin-resistant S. aureus. Notably, S. aureus WTA GlcNAc residues are major antigens and activate the complement system contributing to opsonophagocytosis. WTA glycosylation with a variety of sugars and corresponding glycosyltransferases were also identified in other Gram-positive bacteria, which paves the way for detailed investigations on the diverse roles of WTA modification with sugar residues. | 2014 | 24365646 |