RRC ID 30018
Author Horiuchi T, Maki H, Sekiguchi M.
Title RNase H-defective mutants of Escherichia coli: a possible discriminatory role of RNase H in initiation of DNA replication.
Journal Mol. Gen. Genet.
Abstract Mutants of Escherichia coli completely deficient in RNase H activity were isolated by inserting transposon Tn3 into the structural gene for RNase H, rnh, and its promoter. These rnh- mutants exhibited the following phenotypes; (1) the mutants grew fairly normally, (2) rnh- cells could be transformed with ColE1 derivative plasmids, pBR322 and pML21, though the plasmids were relatively unstable, under non selective conditions, (3) rnh- mutations partially suppressed the temperature-sensitive phenotype of plasmid pSC301, a DNA replication initiation mutant derived from pSC101, (4) rnh- mutations suppressed the temperature-sensitive growth character of dnaAts mutant, (5) rnh- cells showed continued DNA synthesis in the presence of chloramphenicol (stable DNA replication). Based on these findings we propose a model for a role of RNase H in the initiation of chromosomal DNA replication. We suggest that two types of RNA primers for initiation of DNA replication are synthesized in a dnaA/oriC-dependent and -independent manner and that only the dnaA/oriC-dependent primer is involved in the normal DNA replication since the dnaA/oriC independent primer is selectively degraded by RNase H.
Volume 195(1-2)
Pages 17-22
Published 1984
PMID 6092845
MeSH DNA Replication* DNA Transposable Elements Endoribonucleases / genetics* Endoribonucleases / metabolism Escherichia coli / enzymology Escherichia coli / genetics* Genotype Mutation* Phenotype Plasmids Ribonuclease H Species Specificity
Times Cited 59
Prokaryotes E. coli ME8313 ME8314 ME8409