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Negative regulation of mutS and mutH repair gene expression by the Hfq and RpoS global regulators of Escherichia coli K-12.
J Bacteriol. 1997 Dec; 179(23):7476-87.JB

Abstract

The MutS, MutL, and MutH proteins play major roles in several DNA repair pathways. We previously reported that the cellular amounts of MutS and MutH decreased by as much as 10-fold in stationary-phase cultures. Consequently, we tested whether the amounts of MutS, MutL, and MutH were regulated by two global regulators, RpoS (sigma38) and Hfq (HF-I [putative RNA chaperone]), which are involved in stationary-phase transition. We report here that mutations in hfq and rpoS reversed the stationary-phase down-regulation of the amounts of MutS and MutH. hfq regulation of the amount of MutS in stationary-phase cultures was mediated by RpoS-dependent and -independent mechanisms, whereas hfq regulation of the amount of MutH was mediated only through RpoS. Consistent with this interpretation, the amount of MutS but not MutH was regulated by Hfq, but not RpoS, in exponentially growing cells. The amount of MutL remained unchanged in rpoS, hfq-1, and rpoS+, hfq+ strains in exponentially growing and stationary-phase cultures and served as a control. The beta-galactosidase activities of single-copy mutS-lacZ operon and gene fusions suggested that hfq regulates mutS posttranscriptionally in exponentially growing cultures. RNase T2 protection assays revealed increased amounts of mutS transcript that are attributed to increased mutS transcript stability in hfq-1 mutants. Lack of Hfq also increased the amounts and stabilities of transcripts initiated from P(miaA) and P1hfqHS, two of the promoters for hfq, suggesting autoregulation, but did not change the half-life of bulk mRNA. These results suggest that the amounts of MutS and MutH may be adjusted in cells subjected to different stress conditions by an RpoS-dependent mechanism. In addition, Hfq directly or indirectly regulates several genes, including mutS, hfq, and miaA, by an RpoS-independent mechanism that destabilizes transcripts.

Authors+Show Affiliations

Department of Microbiology and Molecular Genetics, University of Texas Houston Medical School, 77030-1501, USA.No affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

9393714

Citation

Tsui, H C., et al. "Negative Regulation of mutS and mutH Repair Gene Expression By the Hfq and RpoS Global Regulators of Escherichia Coli K-12." Journal of Bacteriology, vol. 179, no. 23, 1997, pp. 7476-87.
Tsui HC, Feng G, Winkler ME. Negative regulation of mutS and mutH repair gene expression by the Hfq and RpoS global regulators of Escherichia coli K-12. J Bacteriol. 1997;179(23):7476-87.
Tsui, H. C., Feng, G., & Winkler, M. E. (1997). Negative regulation of mutS and mutH repair gene expression by the Hfq and RpoS global regulators of Escherichia coli K-12. Journal of Bacteriology, 179(23), 7476-87.
Tsui HC, Feng G, Winkler ME. Negative Regulation of mutS and mutH Repair Gene Expression By the Hfq and RpoS Global Regulators of Escherichia Coli K-12. J Bacteriol. 1997;179(23):7476-87. PubMed PMID: 9393714.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Negative regulation of mutS and mutH repair gene expression by the Hfq and RpoS global regulators of Escherichia coli K-12. AU - Tsui,H C, AU - Feng,G, AU - Winkler,M E, PY - 1997/12/11/pubmed PY - 1997/12/11/medline PY - 1997/12/11/entrez SP - 7476 EP - 87 JF - Journal of bacteriology JO - J Bacteriol VL - 179 IS - 23 N2 - The MutS, MutL, and MutH proteins play major roles in several DNA repair pathways. We previously reported that the cellular amounts of MutS and MutH decreased by as much as 10-fold in stationary-phase cultures. Consequently, we tested whether the amounts of MutS, MutL, and MutH were regulated by two global regulators, RpoS (sigma38) and Hfq (HF-I [putative RNA chaperone]), which are involved in stationary-phase transition. We report here that mutations in hfq and rpoS reversed the stationary-phase down-regulation of the amounts of MutS and MutH. hfq regulation of the amount of MutS in stationary-phase cultures was mediated by RpoS-dependent and -independent mechanisms, whereas hfq regulation of the amount of MutH was mediated only through RpoS. Consistent with this interpretation, the amount of MutS but not MutH was regulated by Hfq, but not RpoS, in exponentially growing cells. The amount of MutL remained unchanged in rpoS, hfq-1, and rpoS+, hfq+ strains in exponentially growing and stationary-phase cultures and served as a control. The beta-galactosidase activities of single-copy mutS-lacZ operon and gene fusions suggested that hfq regulates mutS posttranscriptionally in exponentially growing cultures. RNase T2 protection assays revealed increased amounts of mutS transcript that are attributed to increased mutS transcript stability in hfq-1 mutants. Lack of Hfq also increased the amounts and stabilities of transcripts initiated from P(miaA) and P1hfqHS, two of the promoters for hfq, suggesting autoregulation, but did not change the half-life of bulk mRNA. These results suggest that the amounts of MutS and MutH may be adjusted in cells subjected to different stress conditions by an RpoS-dependent mechanism. In addition, Hfq directly or indirectly regulates several genes, including mutS, hfq, and miaA, by an RpoS-independent mechanism that destabilizes transcripts. SN - 0021-9193 UR - https://www.unboundmedicine.com/medline/citation/9393714/Negative_regulation_of_mutS_and_mutH_repair_gene_expression_by_the_Hfq_and_RpoS_global_regulators_of_Escherichia_coli_K_12_ L2 - http://jb.asm.org/cgi/pmidlookup?view=long&pmid=9393714 DB - PRIME DP - Unbound Medicine ER -