title: Global effect of an RNA polymerase β-subunit mutation on gene expression in the radiation-resistant bacterium Deinococcus radiodurans.
abstract: The β-subunit of RNA polymerase, which is involved in rifampin binding, is highly conserved among prokaryotes, and Rifr mutants detected in many bacteria are the result of amino acid changes. Spontaneous rifampin resistance mutations resulting in amino acid replacement (L420R) and deletion (1258-66 9 bp deletion) have been previously isolated in the rpoB gene of Deinococcus radiodurans. In this study, a β-subunit mutation in D. radiodurans resulted in a unique effect on growth rate. We used DNA microarrays and biochemical assays to investigate how the Rifr mutation in the β-subunit led to changes in growth rate via altered regulation of multiple genes. The expression of genes with predicted functions in metabolism, cellular processes and signaling, and information storage and processing were significantly altered in the 9 bp-deletion rpoB mutant. The consensus promoter sequence of up-regulated genes in the 9 bp-deletion rpoB mutant was identified as an AT-rich sequence. Greater levels of reactive oxygen species accumulated in the L420R and 9 bp-deletion rpoB mutants compared with wild type. These results provide insight into the molecular mechanism of how the β-subunit Rifr mutation alters the regulation of multiple genes.
authors.affiliation: Department of Infectious Diseases, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou 310016, China.
authors.forename: Xiaoting
authors.initials: X
authors.lastname: Hua
authors.forename: Hu
authors.initials: H
authors.lastname: Wang
authors.forename: Chao
authors.initials: C
authors.lastname: Wang
authors.forename: Bing
authors.initials: B
authors.lastname: Tian
authors.forename: Yuejin
authors.initials: Y
authors.lastname: Hua
mesh_terms: D012321:DNA-Directed RNA Polymerases / Q000737:chemistry / Q000235:genetics*; D034301:Deinococcus / Q000201:enzymology / Q000235:genetics* / Q000528:radiation effects; D015870:Gene Expression; D009154:Mutation; D011836:Radiation Tolerance; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D017382:Reactive Oxygen Species; D012321:DNA-Directed RNA Polymerases