Open AccessThe helix-turn-helix motif of sigma 54 is involved in recognition of the -13 promoter region
Author(s) -
Mike Merrick,
Sheila Chambers
Publication year - 1992
Publication title -
journal of bacteriology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.652
H-Index - 246
eISSN - 1067-8832
pISSN - 0021-9193
DOI - 10.1128/jb.174.22.7221-7226.1992
Subject(s) - biology , promoter , mutant , sigma factor , helix turn helix , transcription (linguistics) , rna polymerase , sigma , helix (gastropod) , microbiology and biotechnology , site directed mutagenesis , transcription factor , genetics , rna , gene , dna binding protein , gene expression , physics , ecology , linguistics , philosophy , quantum mechanics , snail
Residue Arg-383 in the proposed helix-turn-helix motif of the novel RNA polymerase sigma factor sigma 54 has been changed by site-directed mutagenesis to all possible alternative amino acids. Only two mutants, RK383 and RH383, are active in promoting transcription from either the glnAp2 promoter or the nifL promoter. We constructed a set of mutant derivatives of glnAp2 such that each base in the conserved GG and GC doublets at -24 and -12 was changed to all possible alternatives. All 12 mutant glnAp2 promoters showed a marked promoter-down phenotype with wild-type sigma 54, but RK383 suppressed changes of both G to C and G to T at -13. This result suggests that the sigma 54 helix-turn-helix is involved in recognition of the -13 region of sigma 54-dependent promoters.