Sites of positive and negative regulation in the Bacillus subtilis antiterminators LicT and SacY

Citation
P. Tortosa et al., Sites of positive and negative regulation in the Bacillus subtilis antiterminators LicT and SacY, MOL MICROB, 41(6), 2001, pp. 1381-1393
Citations number
50
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Microbiology
Journal title
MOLECULAR MICROBIOLOGY
ISSN journal
0950-382X → ACNP
Volume
41
Issue
6
Year of publication
2001
Pages
1381 - 1393
Database
ISI
SICI code
0950-382X(200109)41:6<1381:SOPANR>2.0.ZU;2-O
Abstract
The Bacillus subtilis homologous transcriptional antiterminators LicT and S acY control the inducible expression of genes involved in aryl beta -glucos ide and sucrose utilization respectively. Their RNA-binding activity is car ried by the N-terminal domain (CAT), and is regulated by two similar C-term inal domains (PRD1 and PRD2), which are the targets of phosphorylation reac tions catalysed by the phosphoenolpyruvate: sugar phosphotransferase system (PTS). In the absence of the corresponding inducer, LicT is inactivated by BgIP, the PTS permease (Ell) specific for aryl beta -glucosides, and SacY by SacX, a negative regulator homologous to the EII specific for sucrose. L icT, but not SacY, is also subject to a positive control by the general PTS components EI and HPr, which are thought to phosphorylate LicT in the abse nce of carbon catabolite repression. Construction of SacY/LicT hybrids and mutational analysis enabled the location of the sites of this positive regu lation at the two phosphorylatable His207 and His269 within LicT-PRD2, and suggested that the presence of negative charges at these sites is sufficien t for LicT activation in vivo. The BgIP-mediated inhibition process was fou nd to essentially involve His100 of LicT-PRD1, with His159 of the same doma in playing a minor role in this regulation. In vitro experiments indicated that His100 could be phosphorylated directly by the general PTS proteins th is phosphorylation being stimulated by P similar to BgIP. We confirmed that , similarly, the corresponding conserved His99 residue in SacY is the major site of the negative control exerted by SacX on SacY activity. Thus, for b oth antiterminators, the EII-mediated inhibition process seems to rely prim arily on the presence of a negative charge at the first conserved histidine of the PRD1.