Isolation and characterization of mutations in region 1.2 of Escherichia coli sigma(70)

Citation
Ne. Baldwin et Aj. Dombroski, Isolation and characterization of mutations in region 1.2 of Escherichia coli sigma(70), MOL MICROB, 42(2), 2001, pp. 427-437
Citations number
38
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Microbiology
Journal title
MOLECULAR MICROBIOLOGY
ISSN journal
0950-382X → ACNP
Volume
42
Issue
2
Year of publication
2001
Pages
427 - 437
Database
ISI
SICI code
0950-382X(200110)42:2<427:IACOMI>2.0.ZU;2-Q
Abstract
Eubacterial RNA polymerase uses the sigma (sigma) subunit for recognition o f and transcription initiation from promoter DNA sequences. One family of s igma factors includes those related to the primary a factor from Escherichi a coli, sigma (70). Members of the sigma (70) family have four highly conse rved domains, of which regions 2 to 4 are present in all members. Region 1 can be subdivided into regions 1.1 and 1.2. Region 1.1 affects DNA binding by sigma (70) alone, as well as transcription initiation by holoenzyme. Reg ion 1.2, present and highly conserved in most sigma factors, has not yet be en assigned a putative function, although previous work has demonstrated th at it is not required for either association with the core subunits of RNA polymerase or promoter-specific binding by holoenzyme. We generated random single amino acid substitutions targeted to region 1.2 of E. coli sigma (70 ) as well as a deletion of region 1.2, and characterized the behaviour of t he mutant sigma factors both in vivo and in vitro to investigate the functi on of region 1.2 during transcription initiation. In this study, we show th at mutations in region 1.2 can affect promoter binding, open complex and in itiated complex formation and the transition from abortive transcription to elongation.