TABLE 4.

Novel dnaC mutations and their phenotypes

Mutant plasmidNucleotide substitution(s)Amino acid substitution(s)Relative plating efficiencya
KH1061 (recA+ ΔdnaC::cat)MF1061 (recA::Kanr ΔdnaC::cat
pACYC184dnaCNoneNone1.21.3
pACYC184Not relevantNot relevant1.8 × 10−31.2 × 10−5
31-f3G289A, T318A (silent)Gly97Ser1.0 × 10−32.6 × 10−5
157-c2A428GLys143Arg1.4 × 10−31.3 × 10−5
36-c4G289AGly97Ser2.1 × 10−41.4 × 10−5
29-d3A534G (silent), G716TArg239Leu1.6 × 10−42.6 × 10−5
55-c6T425C, A521GMet142Thr, Gln174Arg7.7 × 10−59.3 × 10−6
97-h9T129C (silent), A218GAsn73Ser2.0 × 10−42.0 × 10−5
107-g12A40G, T178CMet14Val, Ser60Pro3.3 × 10−42.8 × 10−5
125-c1G359ACys120Tyr2.1 × 10−47.9 × 10−6
145-f1T89C, A237G (silent), A394T, G565ALeu30Pro, Ile132Phe, Asp189Asn4.1 × 10−42.0 × 10−5
151-a2T86C, A248GLeu29Pro, Asn83Ser2.2 × 10−41.7 × 10−5
239-e10T178A, T213C (silent), A336G (silent), C504A (silent), A632GSer60Thr, Lys211Arg3.1 × 10−41.2 × 10−5
164-g2G82A, T207C (silent), A676TGlu28Lys, Ser226Cys6.0 × 10−41.9 × 10−5
40-g4A71G, A107G, T189C (silent), T254A, A354T (silent), A400G, C483T (silent)Lys24Arg, Gln36Arg, Leu85Stop, Thr134Ala1.6 × 10−51.1 × 10−5
4-g1A712TSer238Cys1.2b1.2b
38-e4T68C, T207C (silent)Phe23Ser1.7b1.2b
54-b6A84T, T706AGlu28Val, Tyr236Asn1.0b0.7b
234-h9T358C, T686ACys120Arg, Val229Glu1.4b0.7b
35-b4T650AVal217Glu6.1 × 10−61.8 × 10−5
246T131CLeu44Pro4.6 × 10−62.3 × 10−5
256-f12A451C, G659AThr151Pro, Arg220His1.0 × 10−52.1 × 10−5
  • a Cultures of the indicated strains carrying pAM34dnaC and the pACYC184 derivative encoding the respective dnaC mutation(s) were serially diluted and plated as described in footnote a of Table 3, but the plating medium was additionally supplemented with chloramphenicol. Relative plating efficiency is defined in footnote a of Table 3.

  • b On medium lacking IPTG, the colonies were either heterogeneous in size or uniformly smaller (for Phe23Ser).