Kogoma T, Maldonado R R
Department of Cell Biology, University of New Mexico Health Sciences Center, Albuquerque 87131, USA.
J Bacteriol. 1997 Apr;179(7):2109-15. doi: 10.1128/jb.179.7.2109-2115.1997.
We examined the effects of mutations in the polA (encoding DNA polymerase I) and polB (DNA polymerase II) genes on inducible and constitutive stable DNA replication (iSDR and cSDR, respectively), the two alternative DNA replication systems of Escherichia coli. The polA25::miniTn10spc mutation severely inactivated cSDR, whereas polA1 mutants exhibited a significant extent of cSDR. cSDR required both the polymerase and 5'-->3' exonuclease activities of DNA polymerase I. A similar requirement for both activities was found in replication of the pBR322 plasmid in vivo. DNA polymerase II was required neither for cSDR nor for iSDR. In addition, we found that the lethal combination of an rnhA (RNase HI) and a polA mutation could be suppressed by the lexA(Def) mutation.
我们研究了大肠杆菌中编码DNA聚合酶I的polA基因和DNA聚合酶II的polB基因的突变对诱导型和组成型稳定DNA复制（分别为iSDR和cSDR）这两种交替DNA复制系统的影响。polA25::miniTn10spc突变严重灭活了cSDR，而polA1突变体表现出显著程度的cSDR。cSDR需要DNA聚合酶I的聚合酶和5'→3'核酸外切酶活性。在体内pBR322质粒的复制中也发现了对这两种活性的类似需求。cSDR和iSDR都不需要DNA聚合酶II。此外，我们发现lexA(Def)突变可以抑制rnhA（核糖核酸酶HI）和polA突变的致死组合。
