• We are sorry, but NCBI web applications do not support your browser and may not function properly. More information
Logo of pnasPNASInfo for AuthorsSubscriptionsAboutThis Article
Proc Natl Acad Sci U S A. Apr 11, 1995; 92(8): 3526–3530.
PMCID: PMC42200

Overexpression of RNase H partially complements the growth defect of an Escherichia coli delta topA mutant: R-loop formation is a major problem in the absence of DNA topoisomerase I.

Abstract

Previous biochemical studies have suggested a role for bacterial DNA topoisomerase (TOPO) I in the suppression of R-loop formation during transcription. In this report, we present several pieces of genetic evidence to support a model in which R-loop formation is dynamically regulated during transcription by activities of multiple DNA TOPOs and RNase H. In addition, our results suggest that events leading to the serious growth problems in the absence of DNA TOPO I are linked to R-loop formation. We show that the overexpression of RNase H, an enzyme that degrades the RNA moiety of an R loop, can partially compensate for the absence of DNA TOPO I. We also note that a defect in DNA gyrase can correct several phenotypes associated with a mutation in the rnhA gene, which encodes the major RNase H activity. In addition, we found that a combination of topA and rnhA mutations is lethal.

Full text

Full text is available as a scanned copy of the original print version. Get a printable copy (PDF file) of the complete article (1.3M), or click on a page image below to browse page by page. Links to PubMed are also available for Selected References.

Images in this article

Click on the image to see a larger version.

Selected References

These references are in PubMed. This may not be the complete list of references from this article.
  • Trucksis M, Depew RE. Identification and localization of a gene that specifies production of Escherichia coli DNA topoisomerase I. Proc Natl Acad Sci U S A. 1981 Apr;78(4):2164–2168. [PMC free article] [PubMed]
  • Sternglanz R, DiNardo S, Voelkel KA, Nishimura Y, Hirota Y, Becherer K, Zumstein L, Wang JC. Mutations in the gene coding for Escherichia coli DNA topoisomerase I affect transcription and transposition. Proc Natl Acad Sci U S A. 1981 May;78(5):2747–2751. [PMC free article] [PubMed]
  • DiNardo S, Voelkel KA, Sternglanz R, Reynolds AE, Wright A. Escherichia coli DNA topoisomerase I mutants have compensatory mutations in DNA gyrase genes. Cell. 1982 Nov;31(1):43–51. [PubMed]
  • Kirkegaard K, Wang JC. Bacterial DNA topoisomerase I can relax positively supercoiled DNA containing a single-stranded loop. J Mol Biol. 1985 Oct 5;185(3):625–637. [PubMed]
  • Pruss GJ, Franco RJ, Chevalier SG, Manes SH, Drlica K. Effects of DNA gyrase inhibitors in Escherichia coli topoisomerase I mutants. J Bacteriol. 1986 Oct;168(1):276–282. [PMC free article] [PubMed]
  • Pruss GJ, Drlica K. Topoisomerase I mutants: the gene on pBR322 that encodes resistance to tetracycline affects plasmid DNA supercoiling. Proc Natl Acad Sci U S A. 1986 Dec;83(23):8952–8956. [PMC free article] [PubMed]
  • Wu HY, Shyy SH, Wang JC, Liu LF. Transcription generates positively and negatively supercoiled domains in the template. Cell. 1988 May 6;53(3):433–440. [PubMed]
  • Liu LF, Wang JC. Supercoiling of the DNA template during transcription. Proc Natl Acad Sci U S A. 1987 Oct;84(20):7024–7027. [PMC free article] [PubMed]
  • Dürrenberger M, Bjornsti MA, Uetz T, Hobot JA, Kellenberger E. Intracellular location of the histonelike protein HU in Escherichia coli. J Bacteriol. 1988 Oct;170(10):4757–4768. [PMC free article] [PubMed]
  • Drolet M, Wu HY, Liu LF. Roles of DNA topoisomerases in transcription. Adv Pharmacol. 1994;29A:135–146. [PubMed]
  • Raji A, Zabel DJ, Laufer CS, Depew RE. Genetic analysis of mutations that compensate for loss of Escherichia coli DNA topoisomerase I. J Bacteriol. 1985 Jun;162(3):1173–1179. [PMC free article] [PubMed]
  • Ogawa T, Pickett GG, Kogoma T, Kornberg A. RNase H confers specificity in the dnaA-dependent initiation of replication at the unique origin of the Escherichia coli chromosome in vivo and in vitro. Proc Natl Acad Sci U S A. 1984 Feb;81(4):1040–1044. [PMC free article] [PubMed]
  • VOGEL HJ, BONNER DM. Acetylornithinase of Escherichia coli: partial purification and some properties. J Biol Chem. 1956 Jan;218(1):97–106. [PubMed]
  • Kanaya S, Crouch RJ. Low levels of RNase H activity in Escherichia coli FB2 rnh result from a single-base change in the structural gene of RNase H. J Bacteriol. 1983 May;154(2):1021–1026. [PMC free article] [PubMed]
  • Bockrath R, Wolff L, Farr A, Crouch RJ. Amplified RNase H activity in Escherichia coli B/r increases sensitivity to ultraviolet radiation. Genetics. 1987 Jan;115(1):33–40. [PMC free article] [PubMed]
  • Itaya M, Crouch RJ. Correlation of activity with phenotypes of Escherichia coli partial function mutants of rnh, the gene encoding RNase H. Mol Gen Genet. 1991 Jul;227(3):433–437. [PubMed]
  • Torrey TA, Atlung T, Kogoma T. dnaA suppressor (dasF) mutants of Escherichia coli are stable DNA replication (sdrA/rnh) mutants. Mol Gen Genet. 1984;196(2):350–355. [PubMed]
  • Subia NL, Kogoma T. Concatemer formation of ColE1-type plasmids in mutants of Escherichia coli lacking RNase H activity. J Mol Biol. 1986 Jun 5;189(3):389–399. [PubMed]
  • Kogoma T, Hong X, Cadwell GW, Barnard KG, Asai T. Requirement of homologous recombination functions for viability of the Escherichia coli cell that lacks RNase HI and exonuclease V activities. Biochimie. 1993;75(1-2):89–99. [PubMed]
  • Kogoma T. Escherichia coli RNA polymerase mutants that enhance or diminish the SOS response constitutively expressed in the absence of RNase HI activity. J Bacteriol. 1994 Mar;176(5):1521–1523. [PMC free article] [PubMed]
  • Jin DJ, Burgess RR, Richardson JP, Gross CA. Termination efficiency at rho-dependent terminators depends on kinetic coupling between RNA polymerase and rho. Proc Natl Acad Sci U S A. 1992 Feb 15;89(4):1453–1457. [PMC free article] [PubMed]

Articles from Proceedings of the National Academy of Sciences of the United States of America are provided here courtesy of National Academy of Sciences

Formats:

Related citations in PubMed

See reviews...See all...

Cited by other articles in PMC

See all...

Links

Recent Activity

Your browsing activity is empty.

Activity recording is turned off.

Turn recording back on

See more...