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The Mechanism Leading to the Negative Dominancy of the Bacillus subtilis Temperature‐Sensitive sigmaA Factors
Author(s) -
Chung Kueimin
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.4.a467-a
Subject(s) - bacillus subtilis , groel , complementation , mutant , chemistry , wild type , heat shock protein , heat shock , gene , biophysics , microbiology and biotechnology , biochemistry , biology , genetics , escherichia coli , bacteria
Bacillus subtilis DB1001 and DB1005 are two temperature‐sensitive (Ts) sigA mutants which contain Ala‐197‐Pro and Ile‐198, 202‐Ala substitutions, respectively, in the promoter −10 binding region of σ A . Complementation analyses revealed that the two mutant sigA are dominant to their wild‐type (Wt) counterpart in sensitivity to growth at elevated temperature. Mechanism leading to the phenomenon has been investigated. Our data revealed that B. subtilis harboring either one of the Ts sigA or in combination with the Wt is unable to induce efficiently the expression of groEL under heat shock. The higher the gene dosage of Ts sigA , the lower the induction of groEL . Moreover, both the Ts σ A are able to form multimers (or soluble aggregate) at 37°C, which then became aggregated at 49°C. More importantly, the Ts σ A are able to enhance the aggregation of co‐existing Wt σ A at elevated temperature, probably through co‐aggregation, which clearly reduces the availability of functional Wt σ A and thus Wt σ A –RNA polymerase activity at elevated temperature. These results support that co‐aggregation of the Wt and Ts σ A is the main reason responsible for the negative dominancy of the Ts sigA .