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pubmed:abstractText |
Escherichia coli rnh mutants defective in RNase H activity display the features of previously described sdrA (stable DNA replication) and dasF (dnaA suppressor) mutants: (i) sustained DNA replication in the absence of protein synthesis, (ii) lack of requirement for dnaA protein and the origin of replication (oriC), and (iii) sensitivity of growth to a rich medium. Both the sdrA mutants (selected for continued DNA replication in the absence of protein synthesis) and the dasF mutants (selected as dnaA suppressors) are defective in RNase H activity, measured in vitro. Furthermore, a 760-base-pair fragment containing the rnh+ structural gene complements the phenotype of each of the rnh, sdrA, and dasF mutants, indicative of a single gene. One function of RNase H in vivo is in the initiation of a cycle of DNA replication at oriC dependent on dnaA+. In keeping with these results, RNase H contributes to the specificity of dnaA protein-dependent replication initiated at oriC in a partially purified enzyme system.
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pubmed:publicationType |
Journal Article,
Comparative Study,
Research Support, U.S. Gov't, P.H.S.,
Research Support, U.S. Gov't, Non-P.H.S.,
Research Support, Non-U.S. Gov't
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