Summary
We have recently shown (Kaiser and Murray 1979) that many E. coli K12 strains carry a defective prophage (Rac) located a few minutes clockwise of the trp operon on the genetic map. The Rac genome contains recE, the determinant for the ATP-independent exonuclease, ExoVIII. E. coli K12 strains which carry sbcA mutations express recE constitutively. This paper describes an investigation of several such strains. We show that the SbcA phenotype may arise from more than one type of mutational change. The most readily explained SbcA phenotype is that of sbcA8 strains in which a large section of the Rac genome (including one hybrid attachment site and probably the prophage repressor gene) is deleted. Three sbcA - strains carry multiple (and probably tandemly repeated) copies of the Rac genome while two others carry a single Rac prophage that is indistinguishable in its hybridisation behaviour from that carried by sbcA + strains.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Appleyard RK (1954) Segregation of new lysogenic types during growth of a doubly lysogenic strain derived from Escherichia coli K12. Genetics 39:440–452
Barbour SD, Nagaishi H, Templin A, Clark AJ (1970) Biochemical and genetic studies of recombination proficiency in Escherichia coli. II Rec+ revertants caused by indirect suppression of Rec- mutations. Proc Natl Acad Sci USA 67:128–135
Campbell A (1961) Sensitive mutants of bacteriophage λ. Virology 14:22–32
Clark AJ (1973) Recombination deficient mutants of E. coli and other bacteria. Ann Rev Genet 7:67–86
Diaz R, Barnsley P, Pritchard RH (1979) Location and characterisation of a new replication origin in the E. coli K12 chromosome. Mol Gen Genet 175:151–157
Diaz R, Pritchard RH (1978) Cloning replication origins from the E. coli K12 chromosome. Nature 275:561–564
Emmerson PT (1968) Recombination deficient mutants in Escherichia coli K12 that map between thyA and argA. Genetics 60:19–30
Evans R, Seeley NR, Kuempel PL (1979) Loss of rac locus DNA in merozygotes of Escherichia coli K12. Mol Gen Genet 175:245–250
Gillen JR, Karu AE, Nagaishi H, Clark AJ (1977) Characterisation of the deoxyribonuclease determined by lambda reverse as exonuclease VIII of Escherichia coli. J Mol Biol 113:27–41
Goldberg AR, Howe M (1969) New mutations in the S cistron of bacteriophage λ affecting host cell lysis. Virology 38:200–202
Gottesman MM, Gottesman ME, Gottesman S, Gellert M (1974) Characterisation of bacteriophage λ reverse as an Escherichia coli phage carrying a unique set of host-derived recombination functions. J Mol Biol 88:471–487
Kaiser K (1979) Defective lambdoid prophages in E. coli K12. Ph D Thesis University of Edinburgh
Kaiser K (1980) The origin of Q-independent derivatives of phage λ. Mol Gen Genet 179:547–554
Kaiser K, Murray NE (1979) Physical characterisation of the “Rac prophage” in E. coli K12. Mol gen Genet 175:159–174
Kushner S, Nagaishi H, Clark AJ (1974) Isolation of exonuclease VIII: the enzyme associated with the sbcA indirect suppressor. Proc Natl Acad Sci USA 71:3593–3597
Lloyd RG (1974) The segregation of the SbcA and Rac phenotypes in an Escherichia coli recB - mutant. Mol Gen Genet 134:249–259
Lloyd RG, Barbour SD (1974) The genetic location of the sbcA gene of Escherichia coli. Mol Gen Genet 134:157–171
Low KB (1973) Restoration by the rac locus of recombinant forming ability in recB - and recC - merozygotes of Escherichia coli K12. Mol Gen Genet 122119–130
Ptashne M, Jeffrey A, Johnson AD, Maurer R, Meyer BJ, Pabo CO, Roberts TM, Sauer RT (1980) How the λ repressor and Cro work Cell 19:1–11
Strike P, Emmerson PT (1974) Degradation of DNA following ultra-violet irradiation of Escherichia coli K12 mutants lacking DNA polymerase I and exonuclease V. Mol Gen Genet 130:39–45
Templin A, Kushner SR, Clark AJ (1972) Genetic analysis of mutations indirectly suppressing recB and recC mutations Genetics 72:205–215
Yanofsky C, Lennox ES (1959) Transduction and recombination study of linkage relationships among the genes controlling tryptophan synthesis in Escherichia coli. Virology 8:425–447
Author information
Authors and Affiliations
Additional information
Communicated by D. Sherratt
Rights and permissions
About this article
Cite this article
Kaiser, K., Murray, N.E. On the nature of sbcA mutations in E. coli K12. Molec. Gen. Genet. 179, 555–563 (1980). https://doi.org/10.1007/BF00271745
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00271745