A mutation in the dam gene of Vibrio cholerae: 2-aminopurine sensitivity with intact GATC methylase activity

Bandyopadhyay, Rupa; Sengupta, Aditya; Das, Jyotirmoy

doi:10.1016/s0006-291x(89)80003-8

Cited by 5 publications

(4 citation statements)

References 23 publications

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“…The previously described dam mutant of another member of the ␥ subdivision of Proteobacteria, V. cholerae, remains somewhat an enigma. The mutant is sensitive to 2-AP, methyl methanesulfonate, and UV but retains methylation of GATC sequences and normal mutability (4). The cloned gene, when highly overexpressed from a multicopy plasmid, can complement an E. coli dam mutant (alleviation of UV and 2-AP sensitivity and increased spontaneous mutability) but does not increase the spontaneous mutability of E. coli or V. cholerae (3), as seen with the overexpressed Dam enzymes of E. coli (21,30) and S. marcescens ( Table 3).…”

Section: Discussionmentioning

confidence: 99%

“…dam mutants are known to be sensitive to the base analogue 2-aminopurine 17). Besides the E. coli mutants, damdeficient strains have been isolated from Salmonella typhimurium (39,45) and Vibrio cholerae (3,4). While the dam mutant of S. typhimurium had a phenotype rather similar to that of the E. coli mutants, the V. cholerae mutant was 2-AP and UV sensitive but did not display enhanced mutability.…”

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confidence: 99%

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Characterization of a dam Mutant of Serratia marcescens and Nucleotide Sequence of the dam Region

et al. 1999

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The DNA of Serratia marcescens has N6-adenine methylation in GATC sequences. Among 2-aminopurine-sensitive mutants isolated from S. marcescensSr41, one was identified which lacked GATC methylation. The mutant showed up to 30-fold increased spontaneous mutability and enhanced mutability after treatment with 2-aminopurine, ethyl methanesulfonate, or UV light. The gene (dam) coding for the adenine methyltransferase (Dam enzyme) of S. marcescens was identified on a gene bank plasmid which alleviated the 2-aminopurine sensitivity and the higher mutability of adam-13::Tn9 mutant ofEscherichia coli. Nucleotide sequencing revealed that the deduced amino acid sequence of Dam (270 amino acids; molecular mass, 31.3 kDa) has 72% identity to the Dam enzyme of E. coli. The dam gene is located between flanking genes which are similar to those found to the sides of the E. coli damgene. The results of complementation studies indicated that like Dam ofE. coli and unlike Dam of Vibrio cholerae, the Dam enzyme of S. marcescens plays an important role in mutation avoidance by allowing the mismatch repair enzymes to discriminate between the parental and newly synthesized strands during correction of replication errors.

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

Characterization of a dam Mutant of Serratia marcescens and Nucleotide Sequence of the dam Region

et al. 1999

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“…The transient undermethylation of G-ATC sequences in newly synthesized strands of DNA, in conjunction with mismatched or unpaired bases, apparently are recognized in the initiation of mismatch repair (5). Mutants in the dam gene are more sensitive to the effects of UV light and other mutagenizing agents (6,7). Additionally, the Dam methylase has been shown to contribute to gene expression (8, 9, 10), including a gene whose product is necessary for the initiation of DNA replication (8).…”

Section: Introductionmentioning

confidence: 99%

Identification and sequence analysis of a methylase gene inPorphyromonas gingivalis

Banas

Ferretti²,

Progulske‐Fox

1991

Nucl Acids Res

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A gene from the periodontal organism Porphyromonas gingivalis has been identified as encoding a DNA methylase. The gene, referred to as pgiIM, has been sequenced and found to contain a reading frame of 864 basepairs. The putative amino acid sequence of the encoded methylase was 288 amino acids, and shared 47% and 31% homology with the Streptococcus pneumoniae DpnII and E. coli Dam methylases, respectively. The activity and specificity of the pgi methylase (M.PgiI) was confirmed by cloning the gene into a dam- strain of E. coli (JM110) and performing a restriction analysis on the isolated DNA with enzymes whose activities depended upon the methylation state of the DNA. The data indicated that M.PgiI, like DpnII and Dam, methylated the adenine residue within the sequence 5'-GATC-3'.

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“…However, sensitivities to chemical agents do not necessarily correlate with increased SMFs. For example, Damnegative V. cholerae is 2-AP sensitive but does not exhibit an increased SMF, and overexpression of V. cholerae dam does not cause increased SMF as observed with the E. coli and S. marcescens dam genes (Bandyopadhyay et al, 1989;Bandyopadhyay & Das, 1994;Herman & Modrich, 1981;Marinus et al, 1984). One possible explanation for differences in the SMF towards a specific antibiotic may be explained by the concentration of GATC sequences within the specific area required to confer resistance (Ostendorf et al, 1999).…”

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confidence: 93%

Dam methylation and putative fimbriae in Klebsiella pneumoniae

Kuehn¹

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DNA adenine methyltransferase (Dam) plays an important role in different bacterial functions. It has been shown that Dam is required for regulation of bacterial replication initiation and is required for proofreading newly synthesized DNA through methylation directed mismatch repair. Dam is also involved in the regulation of different genes and is required for virulence in several different bacterial genera though its degree of importance depends on the specific bacteria being studied. During this work, a Damnegative strain (JSM1) was constructed in Klebsiella pneumoniae strain 43816 to ascertain its importance for K. pneumoniae viability and virulence. To test JSM1 for expression of fimbrial virulence factors, agglutinations were used to detect the presence of type three and type one fimbriae. No differences between 43816 and JSM1 were discernable. Similarly, JSM1 production of capsular material appeared to be unaltered. K. pneumoniae JSM1 virulence in a murine model was examined following intranasal or intraperitoneal inoculation, and it was determined that JSM1 is partially attenuated. Quantitative analysis of 43816 and JSM1 biofilm growth revealed only slight decreases in JSM1 biofilm mass and thickness, but live/dead staining of developed biofilms showed decreased JSM1 biofilm viability over time compared to 43816 biofilms. JSM1 was also examined for alterations in the frequency of spontaneous antibiotic resistance mutations and tested for increased susceptibility to various DNA damaging agents, and statistically significant differences were found for some of the spontaneous antibiotic resistance mutation frequencies tested. Fimbriae in K. pneumoniae are important virulence factors which facilitate respiratory and urinary tract infections in vivo. They also contribute to formation of biofilms which are believed to cause chronic infections and increased antibiotic resistance. Searches for homologous regions within the Klebsiella chromosome using the ABSTRACT DNA adenine methyltransferase (Dam) plays an important role in different bacterial functions. It has been shown that Dam is required for regulation of bacterial replication initiation and is required for proofreading newly synthesized DNA through methylation directed mismatch repair. Dam is also involved in the regulation of different genes and is required for virulence in several different bacterial genera though its degree of importance depends on the specific bacteria being studied. During this work, a Damnegative strain (JSM1) was constructed in Klebsiella pneumoniae strain 43816 to ascertain its importance for K. pneumoniae viability and virulence. To test JSM1 for expression of fimbrial virulence factors, agglutinations were used to detect the presence of type three and type one fimbriae. No differences between 43816 and JSM1 were discernable. Similarly, JSM1 production of capsular material appeared to be unaltered. K. pneumoniae JSM1 virulence in a murine model was examined following intranasal or intraperitoneal inoculation, and it was determined ...

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A mutation in the dam gene of Vibrio cholerae: 2-aminopurine sensitivity with intact GATC methylase activity

Cited by 5 publications

References 23 publications

Characterization of a dam Mutant of Serratia marcescens and Nucleotide Sequence of the dam Region

Characterization of a dam Mutant of Serratia marcescens and Nucleotide Sequence of the dam Region

Identification and sequence analysis of a methylase gene inPorphyromonas gingivalis

Dam methylation and putative fimbriae in Klebsiella pneumoniae

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