The DNA adenine methyltransferase-encoding gene (dam) of Vibrio cholerae

Bandyopadhyay, Rupa; Das, Jyotirmoy

doi:10.1016/0378-1119(94)90732-3

Cited by 16 publications

(8 citation statements)

References 20 publications

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“…The currently proposed resistance management strategy for Bt maize, the high-doselrefuge strategy (1,2,21), requires (i) that plant tissue be very toxic so that heterozygotes for resistance are killed, (ii) that the resistance alleles be very rare. and (iii) that susceptible insects are within an effective mating distance of resistant insects.…”

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An Essential Role for DNA Adenine Methylation in Bacterial Virulence

Heithoff

Sinsheimer

Low

et al. 1999

Science

437

418

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Salmonella typhimurium lacking DNA adenine methylase (Dam) were fully proficient in colonization of mucosal sites but showed severe defects in colonization of deeper tissue sites. These Dam- mutants were totally avirulent and were effective as live vaccines against murine typhoid fever. Dam regulated the expression of at least 20 genes known to be induced during infection; a subset of these genes are among those activated by the PhoP global virulence regulator. PhoP, in turn, affected Dam methylation at specific genomic sites, as evidenced by alterations in DNA methylation patterns. Dam inhibitors are likely to have broad antimicrobial action, and Dam- derivatives of these pathogens may serve as live attenuated vaccines.

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“…They are highly conseived in many pathogenic bacteria that cause significant morbidity and mortality? such as Tiihrio cholei.ue (21), Scrlnio?~ella hplzi (22). pathogenic,E.…”

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An Essential Role for DNA Adenine Methylation in Bacterial Virulence

Heithoff

Sinsheimer

Low

et al. 1999

Science

437

418

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“…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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“…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. The amino acid sequence of the Dam enzyme of V. cholerae was rather different from that of the enzyme of E. coli (3). In order to establish whether the dam gene and its function observed in E. coli and the closely related bacterium S. typhimurium represent a more general type among members of the family Enterobacteriaceae, we have isolated a dam mutant of Serratia marcescens.…”

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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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“…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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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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The DNA adenine methyltransferase-encoding gene (dam) of Vibrio cholerae

Cited by 16 publications

References 20 publications

An Essential Role for DNA Adenine Methylation in Bacterial Virulence

An Essential Role for DNA Adenine Methylation in Bacterial Virulence

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

Dam methylation and putative fimbriae in Klebsiella pneumoniae

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