Properties of Bacillus subtilis sigma A factors with region 1.1 and the conserved Arg-103 at the N terminus of region 1.2 deleted.
sigma factors in the sigma(70) family can be classified into the primary and alternative sigma factors according to their physiological functions and amino acid sequence similarities. The primary sigma factors are composed of four conserved regions, with the conserved region 1 being divided into two subregions. Region 1.1, which is absent from the alternative sigma factor, is poor in conservation; however, region 1.2 is well conserved. We investigated the importance of these two subregions to the function of Bacillus subtilis sigma(A), which belongs to a subgroup of the primary sigma factor lacking a 254-amino-acid spacer between regions 1 and 2. We found that deletion of not more than 100 amino acid residues from the N terminus of sigma(A), which removed part or all region 1.1, did not affect the overall transcription activity of the truncated sigma(A)-RNA polymerase in vitro, indicating that region 1.1 is not required for the functioning of sigma(A) in RNA polymerase holoenzyme. This finding is consistent with the complementation data obtained in vivo. However, region 1.1 is able to negatively modulate the promoter DNA-binding activity of the sigma(A)-RNA polymerase. Further deletion of the conserved Arg-103 at the N terminus of region 1.2 increased the content of stable secondary structures of the truncated sigma(A) and greatly reduced the transcription activity of the truncated sigma(A)-RNA polymerase by lowering the efficiency of transcription initiation after core binding of sigma(A). More importantly, the conserved Arg-103 was also demonstrated to be critical for the functioning of the full-length sigma(A) in RNA polymerase.
Hsu
Hsin-Hsien
HH
Institute of Biochemistry, National Chung-Hsing University, Taichung 40227, Taiwan, Republic of China.
Huang
Wei-Cheng
WC
Chen
Jia-Perng
JP
Huang
Liang-Yin
LY
Wu
Chai-Fong
CF
Chang
Ban-Yang
BY
D000595:Amino Acid Sequence; D001120:Arginine / Q000737:chemistry; D001412:Bacillus subtilis / Q000378:metabolism*; D004252:DNA Mutational Analysis; D012321:DNA-Directed RNA Polymerases / Q000737:chemistry / Q000378:metabolism; D005816:Genetic Complementation Test; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D016415:Sequence Alignment; D012808:Sigma Factor / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
D012808:Sigma Factor; D001120:Arginine; D012321:DNA-Directed RNA Polymerases