Summary
The replication cycle of Escherichia coli dam mutants was analysed and compared with that of isogenic Dam+ strains. Marker frequency analyses indicated no gross difference between the strains. In the Dam− as well as in the Dam+ bacteria, initiation most likely occurs at oriC, replication forks move at a constant and invariant velocity, and termination takes place in the terC region. An analysis of replication terminator activity indicated that this activity is unaffected by the methylation status. Taken together with previous results, our data are compatible with Dam methylation controlling initiation timing but no subsequent step of the replication process.
References
Bakker A, Smith DW (1989) Methylation of GATC sites is required for precise timing between rounds of DNA replication in Escherichia coli. J Bacteriol 171:5738–5742
Barras F, Marinus MG (1989) The great GATC: DNA methylation in E. coli. TIG 5:139–143
Bird R, Louarn J, Martuscelli J, Caro L (1972) Origin and sequence of chromosome replication in Escherichia coli. J Mol Biol 70:549–566
Boye E, Lobner-Olesen A, Skarstad K (1988) Timing of chromosomal replication in Escherichia coli. Biochim Biophys Acta 951:359–364
Churchward G, Bremer H (1977) Determination of deoxyribonucleic acid replication time in exponentially growing Escherichia coli B/r. J Bacteriol 130:1206–1213
Claverys JP, Lacks SA (1986) Heteroduplex deoxyribonucleic acid base mismatch repair in bacteria. Microbiol Rev 50:133–165
de Massy B, Patte J, Louarn JM, Bouché JP (1984) oriX: a new replication origin in E. coli. Cell 36:221–227
de Massy B, Béjar S, Louarn J, Louarn JM, Bouché JP (1987) Inhibition of replication forks exiting the terminus region of the Escherichia coli chromosome occurs at two loci separated by 5 min. Proc Natl Acad Sci USA 84:1759–1763
François V, Louarn J, Louarn JM (1989) The terminus of the Escherichia coli chromosome is flanked by several polar replication pause sites. Mol Microbiol 3:995–1002
Hidaka M, Ahiyama M, Horiuchi T (1988) A consensus sequence of three DNA replication terminus sites on the E. coli chromosome is highly homologous to the terR sites of the R6K plasmid. Cell 55:467–475
Hill TM, Henson JM, Kuempel PL (1987) The terminus region of the Escherichia coli chromosome contains two separable loci that exhibit polar inhibition of replication. Proc Natl Acad Sci USA 84:1754–1758
Kohara Y, Akiyama K, Isono K (1987) The physical map of the whole E. coli chromosome: application of a new strategy for rapid analysis and sorting of a large genomic library. Cell 50:495–508
Marinus MG (1987) DNA methylation in Escherichia coli. Annu Rev Genet 21:113–132
Marinus MG, Carraway M, Frey AZ, Brown L, Arraj JA (1983) Insertion mutations in the dam gene of Escherichia coli K12. Mol Gen Genet 191:288–289
Meijer M, Beck E, Hansen FG, Bergams HEG, Messer W, Von Meyenburg K, Schaller H (1979) Nucleotide sequence of the origin of replication of Escherichia coli K12 chromosome. Proc Natl Acad Sci USA 76:580–584
Messer W, Noyer-Weidner M (1988) Timing and targeting: The biological functions of Dam methylation in E. coli. Cell 54:735–737
Messer W, Bellekes V, Lother H (1985) Effect of dam methylation on the activity of the E. coli replication origin, oriC. EMBO J 4:1327–1332
Modrich P (1987) DNA mismatch correction. Annu Rev Biochem 56:435–466
Ogden GB, Pratt MJ, Schaechter M (1988) The replicative origin of the E. coli chromosome binds to cell membranes only when hemimethylated. Cell 54:127–135
Parker B, Marinus MMG (1988) A simple and rapid method to obtain substitution mutations in Escherichia coli: isolation of a dam deletion/insertion mutation. Gene 73:531–535
Peterson KR, Wertman KF, Mount DW, Marinus MG (1985) Viability of Escherichia coli K12 DNA adenine methylase (dam) mutants requires increased expression of specific genes in the SOS regulon. Mol Gen Genet 201:14–19
Phillips TA, Vaughn V, Bloch PL, Neidhardt FC (1987) Geneprotein index of Escherichia coli K12. In: Neidhardt FC (ed) Escherichia coli and Salmonella typhimurium. Cellular and molecular biology. American Society for Microbiology, Washington DC, pp 919–966
Rebollo J-E, François V, Louarn JM (1988) Detection and possible role of two large nondivisible zones on the Escherichia coli chromosome. Proc Natl Acad Sci USA 85:9391–9395
Roberts D, Hoopes BC, McClure W, Kleckner N (1985) IS10 transposition is regulated by DNA adenine methylation. Cell 43:117–130
Russel DW, Zinder ND (1987) Hemimethylation prevents DNA replication in E. coli. Cell 50:1071–1079
Smith DW, Garland AM, Herman G, Enns RE, Baker TA, Zyskind JW (1985) Importance of methylation of oriC GATC sites in initiation of DNA replication in Escherichia coli. EMBO J 4:1319–1326
Sueoka N, Yoshikawa H (1965) The chromosome of Bacillus subtilis. I. Theory of marker frequency analysis. Genetics 52:747–757
Sugimoto K, Oka A, Sugisaki M, Takanami M, Nishimura A, Yasuda Y, Hirota Y (1979) Nucleotide sequence of Escherichia coli K12 replication origin. Proc Natl Acad Sci USA 76:575–579
Author information
Authors and Affiliations
Additional information
Communicated by R. Devoret
Rights and permissions
About this article
Cite this article
Louarn, J., François, V. & Louarn, JM. Chromosome replication pattern in dam mutants of Escherichia coli . Molec. Gen. Genet. 221, 291–294 (1990). https://doi.org/10.1007/BF00261735
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00261735