# | Rank | Similarity | Title + Abs. | Year | PMID |
|---|---|---|---|---|---|
| 0 | 1 | 2 | 3 | 4 | 5 |
| 351 | 0 | 0.9926 | Rapid and efficient cloning of proviral flanking fragments by kanamycin resistance gene complementation. We have developed a technique for the rapid cloning of unknown flanking regions of transgenic DNA. We complemented a truncated kanamycin resistance gene of a bacterial plasmid with a neomycin resistance gene fragment from a gene transfer vector. Optimized transformation conditions allowed us to directly select for kanamycin-resistant bacteria. We cloned numerous proviral flanking fragments from growth factor-independent cell mutants that were obtained after infection with a replication incompetent retroviral vector and identified integrations into the cyclin D2 and several unknown genomic sequences. We anticipate that our method could be adapted to various vector systems that are used to tag and identify genes and to map genomes. | 1999 | 9863001 |
| 448 | 1 | 0.9926 | Gene-for-gene interactions of five cloned avirulence genes from Xanthomonas campestris pv. malvacearum with specific resistance genes in cotton. A total DNA clone bank of a strain of Xanthomonas campestris pv. malvacearum (Xcm) was constructed in the cosmid vector pSa747 and transfected into Escherichia coli. The Xcm strain carries at least nine identifiable avirulence (A) genes. Clones in E. coli were mated individually into a recombination-proficient Xcm isolate carrying no known A genes. Screening was for incompatibility on congenic cotton host lines that differ by single specific resistance (R) genes. Ten different cosmid clones conferring race-specific avirulence were recovered. In most cases, the same A gene clone was recovered independently several times. Using the congenic host lines and the merodiploid transconjugant pathogen strains, five of the A genes were shown to specifically interact, gene-for-gene, with individual R genes in the congenic cotton lines. Some A/R gene interactions appeared qualitatively different from others, suggesting that the physiological mechanism(s) of gene-for-gene specified incompatibility may be unique to the interactive gene pair. All A genes appeared to be chromosomally determined, three were found linked on a single 32-kilobase clone, and the rest were spaced more than 31 kilobases apart. Colinearity of the cosmid inserts with the Xcm recipient (carrying no known A genes) chromosome was demonstrated in two of the three tested. This and other evidence suggests that at least some A genes in bacteria may have the equivalent of virulence (a) alleles. The genetics of race specificity in this phytopathogenic bacterium appeared in all respects to be identical to that found in phytopathogenic fungi. | 1986 | 16593751 |
| 3059 | 2 | 0.9925 | Genome Analysis of Kingella kingae Strain KWG1 Reveals How a β-Lactamase Gene Inserted in the Chromosome of This Species. We describe the genome of a penicillinase-producing Kingella kingae strain (KWG1), the first to be isolated in continental Europe, whose bla(TEM-1) gene was, for the first time in this species, found to be chromosomally inserted. The bla(TEM) gene is located in an integrative and conjugative element (ICE) inserted in Met-tRNA and comprising genes that encode resistance to sulfonamides, streptomycin, and tetracycline. This ICE is homologous to resistance-conferring plasmids of K. kingae and other Gram-negative bacteria. | 2016 | 26574009 |
| 5125 | 3 | 0.9923 | Do we still need Illumina sequencing data? Evaluating Oxford Nanopore Technologies R10.4.1 flow cells and the Rapid v14 library prep kit for Gram negative bacteria whole genome assemblies. The best whole genome assemblies are currently built from a combination of highly accurate short-read sequencing data and long-read sequencing data that can bridge repetitive and problematic regions. Oxford Nanopore Technologies (ONT) produce long-read sequencing platforms and they are continually improving their technology to obtain higher quality read data that is approaching the quality obtained from short-read platforms such as Illumina. As these innovations continue, we evaluated how much ONT read coverage produced by the Rapid Barcoding Kit v14 (SQK-RBK114) is necessary to generate high-quality hybrid and long-read-only genome assemblies for a panel of carbapenemase-producing Enterobacterales bacterial isolates. We found that 30× long-read coverage is sufficient if Illumina data are available, and that more (at least 100× long-read coverage is recommended for long-read-only assemblies. Illumina polishing is still improving single nucleotide variants (SNVs) and INDELs in long-read-only assemblies. We also examined if antimicrobial resistance genes could be accurately identified in long-read-only data, and found that Flye assemblies regardless of ONT coverage detected >96% of resistance genes at 100% identity and length. Overall, the Rapid Barcoding Kit v14 and long-read-only assemblies can be an optimal sequencing strategy (i.e., plasmid characterization and AMR detection) but finer-scale analyses (i.e., SNV) still benefit from short-read data. | 2024 | 38354391 |
| 9983 | 4 | 0.9923 | A new drug design strategy: Killing drug resistant bacteria by deactivating their hypothetical genes. Despite that a bacterial genome is complicated by large numbers of horizontally transferred (HT) genes and function unknown hypothetical (FUN) genes, the Genic-Transcriptional-Stop-Signals-Ratio (TSSR) of a genome shows that HT and FUN genes are complementary to all other genes in the genome. When HT or certain FUN genes are omitted from the Escherichia coli K-12 genome, its Genomic-TSSR value becomes totally incomparable to other E. coli strains. The Genic-TSSR correlation tree of a pathogen shows that some FUN genes would form a unique cluster. Removing these genes by site-specific mutation or gene-knockout should lead to the demise of this pathogen. | 2016 | 27901648 |
| 437 | 5 | 0.9923 | Cloning of genes responsible for acetic acid resistance in Acetobacter aceti. Five acetic acid-sensitive mutants of Acetobacter aceti subsp. aceti no. 1023 were isolated by mutagenesis with N-methyl-N'-nitro-N-nitrosoguanidine. Three recombinant plasmids that complemented the mutations were isolated from a gene bank of the chromosome DNA of the parental strain constructed in Escherichia coli by using cosmid vector pMVC1. One of these plasmids (pAR1611), carrying about a 30-kilobase-pair (kb) fragment that conferred acetic acid resistance to all five mutants, was further analyzed. Subcloning experiments indicated that a 8.3-kb fragment was sufficient to complement all five mutations. To identify the mutation loci and genes involved in acetic acid resistance, insertional inactivation was performed by insertion of the kanamycin resistance gene derived from E. coli plasmid pACYC177 into the cloned 8.3-kb fragment and successive integration into the chromosome of the parental strain. The results suggested that three genes, designated aarA, aarB, and aarC, were responsible for expression of acetic acid resistance. Gene products of these genes were detected by means of overproduction in E. coli by use of the lac promoter. The amino acid sequence of the aarA gene product deduced from the nucleotide sequence was significantly similar to those of the citrate synthases (CSs) of E. coli and other bacteria. The A. aceti mutants defective in the aarA gene were found to lack CS activity, which was restored by introduction of a plasmid containing the aarA gene. A mutation in the CS gene of E. coli was also complemented by the aarA gene. These results indicate that aarA is the CS gene. | 1990 | 2156811 |
| 379 | 6 | 0.9922 | Broad host range DNA cloning system for gram-negative bacteria: construction of a gene bank of Rhizobium meliloti. A broad host range cloning vehicle that can be mobilized at high frequency into Gram-negative bacteria has been constructed from the naturally occurring antibiotic resistance plasmid RK2. The vehicle is 20 kilobase pairs in size, encodes tetracycline resistance, and contains two single restriction enzyme sites suitable for cloning. Mobilization is effected by a helper plasmid consisting of the RK2 transfer genes linked to a ColE1 replicon. By use of this plasmid vehicle, a gene bank of the DNA from a wild-type strain of Rhizobium meliloti has been constructed and established in Escherichia coli. One of the hybrid plasmids in the bank contains a DNA insert of approximately 26 kilobase pairs which has homology to the nitrogenase structural gene region of Klebsiella pneumoniae. | 1980 | 7012838 |
| 8757 | 7 | 0.9922 | Soybean FGAM synthase promoters direct ectopic nematode feeding site activity. Soybean cyst nematode (SCN) resistance in soybean is a complex oligogenic trait. One of the most important nematode resistance genes, rhg1, has been mapped to a distal region of molecular linkage group G in soybean. A simplified genetic system to identify soybean genes with modified expression in response to SCN led to the identification of several genes within the nematode feeding sites. The genes were mapped to reveal their linkage relationship to known QTLs associated with soybean cyst nematode (SCN) resistance. One candidate, a phosphoribosyl formyl glycinamidine (FGAM) synthase (EC 6.3.5.3) gene, mapped to the same genomic interval as the major SCN resistance gene rhg1 within linkage group G. Isolation of FGAM synthase from a soybean bacterial artificial chromosome (BAC) library revealed two highly homologous paralogs. The genes appeared to be well conserved between bacteria and humans. Promoter analysis of the two soybean homologs was carried out with the Arabidopsis thaliana - Heterodera schachtii system to investigate gene response to nematode feeding. The two promoters and their derived deletion constructions effected green fluorescent protein (GFP) expression within nematode feeding sites. The 1.0-kb promoter sequence immediately adjacent to the translation start site was sufficient to direct expression of GFP within syncytia. A wound-inducible element and a floral organ expression sequence were also identified within these promoters. Although a nematode-responsive element could not be identified, the observed expression of GFP within feeding sites supports the hypothesis that plant gene expression is redirected within feeding sites to benefit the parasite. | 2004 | 15060594 |
| 429 | 8 | 0.9921 | An integrative vector exploiting the transposition properties of Tn1545 for insertional mutagenesis and cloning of genes from gram-positive bacteria. We have constructed and used an integrative vector, pAT112, that takes advantage of the transposition properties (integration and excision) of transposon Tn1545. This 4.9-kb plasmid is composed of: (i) the replication origin of pACYC184; (ii) the attachment site (att) of Tn1545; (iii) erythromycin-and kanamycin-resistance-encoding genes for selection in Gram- and Gram+ bacteria; and (iv) the transfer origin of IncP plasmid RK2, which allows mobilization of the vector from Escherichia coli to various Gram+ recipients. Integration of pAT112 requires the presence of the transposon-encoded integrase, Int-Tn, in the new host. This vector retains the insertion specificity of the parental element Tn1545 and utilises it to carry out insertional mutagenesis, as evaluated in Enterococcus faecalis. Since pAT112 contains the pACYC184 replicon and lacks most of the restriction sites that are commonly used for molecular cloning, a gene from a Gram+ bacterium disrupted with this vector can be recovered in E. coli by cleavage of genomic DNA, intramolecular ligation and transformation. Regeneration of the gene, by excision of pAT112, can be obtained in an E. coli strain expressing the excisionase and integrase of Tn1545. The functionality of this system was illustrated by characterization of an IS30-like structure in the chromosome of En. faecalis. Derivatives pAT113 and pAT114 contain ten unique cloning sites that allow screening of recombinants having DNA inserts by alpha-complementation in E. coli carrying the delta M15 deletion of lacZ alpha. These vectors are useful to clone and introduce foreign genes into the genomes of Gram+ bacteria. | 1991 | 1657722 |
| 4453 | 9 | 0.9921 | dfrA trimethoprim resistance genes found in Gram-negative bacteria: compilation and unambiguous numbering. To track the spread of antibiotic resistance genes, accurate identification of individual genes is essential. Acquired trimethoprim resistance genes encoding trimethoprim-insensitive homologues of the sensitive dihydrofolate reductases encoded by the folA genes of bacteria are increasingly found in genome sequences. However, naming and numbering in publicly available records (journal publications or entries in the GenBank non-redundant DNA database) has not always been unambiguous. In addition, the nomenclature has evolved over time. Here, the changes in nomenclature and the most commonly encountered problems and pitfalls affecting dfrA gene identification arising from historically incorrect or inaccurate numbering are explained. The complete set of dfrA genes/DfrA proteins found in Gram-negative bacteria for which readily searchable sequence information is currently available has been compiled using less than 98% identity for both the gene and the derived protein sequence as the criteria for assignment of a new number. In most cases, trimethoprim resistance has been demonstrated. The gene context, predominantly in a gene cassette or near the ori end of CR1 or CR2, is also covered. The RefSeq database that underpins the programs used to automatically identify resistance genes in genome data sets has been curated to assign all sequences listed to the correct number. This led to the assignment of corrected or new gene numbers to several mis-assigned sequences. The unique numbers assigned for the dfrA/DfrA set are now listed in the RefSeq database, which we propose provides a way forward that should end future duplication of numbers and the confusion that causes. | 2021 | 34180526 |
| 499 | 10 | 0.9921 | Characterization of the genomically encoded fosfomycin resistance enzyme from Mycobacterium abscessus. Mycobacterium abscessus belongs to a group of rapidly growing mycobacteria (RGM) and accounts for approximately 65-80% of lung disease caused by RGM. It is highly pathogenic and is considered the prominent Mycobacterium involved in pulmonary infection in patients with cystic fibrosis and chronic pulmonary disease (CPD). FosM is a putative 134 amino acid fosfomycin resistance enzyme from M. abscessus subsp. bolletii that shares approximately 30-55% sequence identity with other vicinal oxygen chelate (VOC) fosfomycin resistance enzymes and represents the first of its type found in any Mycobacterium species. Genes encoding VOC fosfomycin resistance enzymes have been found in both Gram-positive and Gram-negative pathogens. Given that FosA enzymes from Gram-negative bacteria have evolved optimum activity towards glutathione (GSH) and FosB enzymes from Gram-positive bacteria have evolved optimum activity towards bacillithiol (BSH), it was originally suggested that FosM might represent a fourth class of enzyme that has evolved to utilize mycothiol (MSH). However, a sequence similarity network (SSN) analysis identifies FosM as a member of the FosX subfamily, indicating that it may utilize water as a substrate. Here we have synthesized MSH and characterized FosM with respect to divalent metal ion activation and nucleophile selectivity. Our results indicate that FosM is a Mn(2+)-dependent FosX-type hydrase with no selectivity toward MSH or other thiols as analyzed by NMR and mass spectroscopy. | 2019 | 32952996 |
| 378 | 11 | 0.9921 | Construction and use of a self-cloning promoter probe vector for gram-negative bacteria. Transposon Tn5 has been used extensively for the genetic analysis of Gram- bacteria. We describe here the construction and use of a Tn5 derivative which contains the ColE1 origin of DNA replication, thereby allowing the cloning of DNA adjacent to the Tn without the need for construction of genomic libraries. The Tn is derived from Tn5-B21 [Simon et al., Gene 80 (1989) 161-169] and contains a promoter-probe lacZ gene and genes encoding resistance to tetracycline and beta-lactams. It is housed within a mobilisable suicide plasmid which can be transferred to a wide range of Gram- bacteria. The Tn was tested using pyoverdine siderophore-synthesis genes (pvd) from Pseudomonas aeruginosa. The simple cloning procedure allowed 15.9 kb of pvd-associated DNA to be cloned; in addition, the lacZ reporter gene allowed the transcription of pvd genes to be studied. The bacteria were resistant to carbenicillin only if the Tn (and hence the beta-lactamase-encoding gene) was downstream from an active promoter. | 1993 | 8386128 |
| 1795 | 12 | 0.9920 | Accessory genome of the multi-drug resistant ocular isolate of Pseudomonas aeruginosa PA34. Bacteria can acquire an accessory genome through the horizontal transfer of genetic elements from non-parental lineages. This leads to rapid genetic evolution allowing traits such as antibiotic resistance and virulence to spread through bacterial communities. The study of complete genomes of bacterial strains helps to understand the genomic traits associated with virulence and antibiotic resistance. We aimed to investigate the complete accessory genome of an ocular isolate of Pseudomonas aeruginosa strain PA34. We obtained the complete genome of PA34 utilising genome sequence reads from Illumina and Oxford Nanopore Technology followed by PCR to close any identified gaps. In-depth genomic analysis was performed using various bioinformatics tools. The susceptibility to heavy metals and cytotoxicity was determined to confirm expression of certain traits. The complete genome of PA34 includes a chromosome of 6.8 Mbp and two plasmids of 95.4 Kbp (pMKPA34-1) and 26.8 Kbp (pMKPA34-2). PA34 had a large accessory genome of 1,213 genes and had 543 unique genes not present in other strains. These exclusive genes encoded features related to metal and antibiotic resistance, phage integrase and transposons. At least 24 genomic islands (GIs) were predicated in the complete chromosome, of which two were integrated into novel sites. Eleven GIs carried virulence factors or replaced pathogenic genes. A bacteriophage carried the aminoglycoside resistance gene (AAC(3)-IId). The two plasmids carried other six antibiotic resistance genes. The large accessory genome of this ocular isolate plays a large role in shaping its virulence and antibiotic resistance. | 2019 | 30986237 |
| 377 | 13 | 0.9920 | Construction of improved plasmid vectors for promoter characterization in Pseudomonas aeruginosa and other gram-negative bacteria. We report the construction of two broad host range promoter-probe plasmid vectors for rapid analysis of promoters in Gram-negative bacteria. The new vectors, pME4507 and pME4510, carry carbenicillin and gentamycin resistance genes, respectively, and are small sized (4 kb) with a flexible multiple cloning site to facilitate directional cloning of putative promoter elements. The vectors allow rapid plate-based screening for promoter activities, using beta-galactosidase as the reporter enzyme. In the absence of an inserted promoter fragment, they display very low background activity, making them a useful tool for analysis of low expression level promoters. | 1998 | 9851050 |
| 5201 | 14 | 0.9920 | Complete genome of Enterobacter sichuanensis strain SGAir0282 isolated from air in Singapore. BACKGROUND: Enterobacter cloacae complex (ECC) bacteria, such as E. cloacae, E. sichuanensis, E. kobei, and E. roggenkampii, have been emerging as nosocomial pathogens. Many strains isolated from medical clinics were found to be resistant to antibiotics, and in the worst cases, acquired multidrug resistance. We present the whole genome sequence of SGAir0282, isolated from the outdoor air in Singapore, and its relevance to other ECC bacteria by in silico genomic analysis. RESULTS: Complete genome assembly of E. sichuanensis strain SGAir0282 was generated using PacBio RSII and Illumina MiSeq platforms, and the datasets were used for de novo assembly using Hierarchical Genome Assembly Process (HGAP) and error corrected with Pilon. The genome assembly consisted of a single contig of 4.71 Mb and with a G+C content of 55.5%. No plasmid was detected in the assembly. The genome contained 4371 coding genes, 83 tRNA and 25 rRNA genes, as predicted by NCBI's Prokaryotic Genome Annotation Pipeline (PGAP). Among the genes, the antibiotic resistance related genes were included: Streptothricin acetdyltransferase (SatA), fosfomycin resistance protein (FosA) and metal-dependent hydrolases of the beta-lactamase superfamily I (BLI). CONCLUSION: Based on whole genome alignment and phylogenetic analysis, the strain SGAir0282 was identified to be Enterobacter sichuanensis. The strain possesses gene clusters for virulence, disease and defence, that can also be found in other multidrug resistant ECC type strains. | 2020 | 32127921 |
| 375 | 15 | 0.9920 | A mariner transposon vector adapted for mutagenesis in oral streptococci. This article describes the construction and characterization of a mariner-based transposon vector designed for use in oral streptococci, but with a potential use in other Gram-positive bacteria. The new transposon vector, termed pMN100, contains the temperature-sensitive origin of replication repATs-pWV01, a selectable kanamycin resistance gene, a Himar1 transposase gene regulated by a xylose-inducible promoter, and an erythromycin resistance gene flanked by himar inverted repeats. The pMN100 plasmid was transformed into Streptococcus mutans UA159 and transposon mutagenesis was performed via a protocol established to perform high numbers of separate transpositions despite a low frequency of transposition. The distribution of transposon inserts in 30 randomly picked mutants suggested that mariner transposon mutagenesis is unbiased in S. mutans. A generated transposon mutant library containing 5000 mutants was used in a screen to identify genes involved in the production of sucrose-dependent extracellular matrix components. Mutants with transposon inserts in genes encoding glycosyltransferases and the competence-related secretory locus were predominantly found in this screen. | 2014 | 24753509 |
| 8452 | 16 | 0.9920 | Functional differentiation and spatial-temporal co-expression networks of the NBS-encoding gene family in Jilin ginseng, Panax ginseng C.A. Meyer. Ginseng, Panax ginseng C.A. Meyer, is one of the most important medicinal plants for human health and medicine. It has been documented that over 80% of genes conferring resistance to bacteria, viruses, fungi and nematodes are contributed by the nucleotide binding site (NBS)-encoding gene family. Therefore, identification and characterization of NBS genes expressed in ginseng are paramount to its genetic improvement and breeding. However, little is known about the NBS-encoding genes in ginseng. Here we report genome-wide identification and systems analysis of the NBS genes actively expressed in ginseng (PgNBS genes). Four hundred twelve PgNBS gene transcripts, derived from 284 gene models, were identified from the transcriptomes of 14 ginseng tissues. These genes were classified into eight types, including TNL, TN, CNL, CN, NL, N, RPW8-NL and RPW8-N. Seven conserved motifs were identified in both the Toll/interleukine-1 receptor (TIR) and coiled-coil (CC) typed genes whereas six were identified in the RPW8 typed genes. Phylogenetic analysis showed that the PgNBS gene family is an ancient family, with a vast majority of its genes originated before ginseng originated. In spite of their belonging to a family, the PgNBS genes have functionally dramatically differentiated and been categorized into numerous functional categories. The expressions of the across tissues, different aged roots and the roots of different genotypes. However, they are coordinating in expression, forming a single co-expression network. These results provide a deeper understanding of the origin, evolution and functional differentiation and expression dynamics of the NBS-encoding gene family in plants in general and in ginseng particularly, and a NBS gene toolkit useful for isolation and characterization of disease resistance genes and for enhanced disease resistance breeding in ginseng and related species. | 2017 | 28727829 |
| 354 | 17 | 0.9920 | New cloning vectors to facilitate quick allelic exchange in gram-negative bacteria. New cloning vectors have been developed with features to enhance quick allelic exchange in gram-negative bacteria. The conditionally replicative R6K and transfer origins facilitate conjugation and chromosomal integration into a variety of bacterial species, whereas the sacB gene provides counterselection for allelic exchange. The vectors have incorporated the lacZ alpha fragment with an enhanced multicloning site for easy blue/white screening and priming sites identified for efficient in vivo assembly or other DNA assembly cloning techniques. Different antibiotic resistance markers allow versatility for use with different bacteria, and transformation into an Escherichia coli strain capable of conjugation enables a quick method for allelic exchange. As a proof of principle, the authors used these vectors to inactivate genes in Vibrio cholerae and Salmonella typhimurium. | 2021 | 33492170 |
| 451 | 18 | 0.9920 | Functional Analysis of the Acinetobacter baumannii XerC and XerD Site-Specific Recombinases: Potential Role in Dissemination of Resistance Genes. Modules composed of a resistance gene flanked by Xer site-specific recombination sites, the vast majority of which were found in Acinetobacter baumannii, are thought to behave as elements that facilitate horizontal dissemination. The A. baumannii xerC and xerD genes were cloned, and the recombinant clones used to complement the cognate Escherichia coli mutants. The complemented strains supported the resolution of plasmid dimers, and, as is the case with E. coli and Klebsiella pneumoniae plasmids, the activity was enhanced when the cells were grown in a low osmolarity growth medium. Binding experiments showed that the partially purified A. baumannii XerC and XerD proteins (XerC(Ab) and XerD(Ab)) bound synthetic Xer site-specific recombination sites, some of them with a nucleotide sequence deduced from existing A. baumannii plasmids. Incubation with suicide substrates resulted in the covalent attachment of DNA to a recombinase, probably XerC(Ab), indicating that the first step in the recombination reaction took place. The results described show that XerC(Ab) and XerD(Ab) are functional proteins and support the hypothesis that they participate in horizontal dissemination of resistant genes among bacteria. | 2020 | 32668667 |
| 430 | 19 | 0.9919 | Cloning and characterization of EcoRI and HindIII restriction endonuclease-generated fragments of antibiotic resistance plasmids R6-5 and R6. DNA fragments generated by the EcoRI of HindIII endonucleases from the low copy number antibiotic resistance plasmids R6 and R6-5 were separately cloned using the high copy number ColE1 or pML21 plasmid vectors and the insertional inactivation procedure. The hybrid plasmids that were obtained were used to determine the location of the EcoRI and HindIII cleavage sites on the parent plasmid genomes by means of electron microscope heteroduplex analysis and agarose gel electrophoresis. Ultracentrifugation of the cloned fragments in caesium chloride gradients localized the high buoyant density regions of R6-5 to fragments that carry the genes for resistance to streptomycin-spectinomycin, sulfonamide, and mercury and a low buoyant density region to fragments that carry the tetracycline resistance determinant. Functional analysis of hybrid plasmids localized a number of plasmid properties such as resistances to antibiotics and mercury and several replication functions to specific regions of the R6-5 genome. Precise localisation of the genes for resistance to chloramphenicol, kanamycin, fusidic acid and tetracycline was possible due to the presence of identified restriction endonuclease cleavage sites within these determinants. Only one region competent for autonomous replication was identified on the R6-5 plasmid genome and this was localized to EcoRI fragment 2 and HindIII fragment 1. However, two additional regions of replication activity designated RepB and RepC, themselves incapable of autonomous replication but capable supporting replication of a linked ColE1 plasmid in polA- bacteria, were also identified. | 1978 | 672900 |