Spo0A directly controls the switch from acid to solvent production in solvent-forming clostridia

Citation
A. Ravagnani et al., Spo0A directly controls the switch from acid to solvent production in solvent-forming clostridia, MOL MICROB, 37(5), 2000, pp. 1172-1185
Citations number
81
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Microbiology
Journal title
MOLECULAR MICROBIOLOGY
ISSN journal
0950-382X → ACNP
Volume
37
Issue
5
Year of publication
2000
Pages
1172 - 1185
Database
ISI
SICI code
0950-382X(200009)37:5<1172:SDCTSF>2.0.ZU;2-Z
Abstract
The spoOA genes of Clostridium beijerinckii NCIMB 8052 and Clostridium cell ulolyticum ATCC 35319 were isolated and characterized. The C-terminal DNA-b inding domains of the predicted products of spoOA from these two organisms, as well as 16 other taxonomically diverse species of Bacillus and Clostrid ium, show extensive amino acid sequence conservation (56% identity, 65% sim ilarity over 104 residues). A 12-amino-acid motif (SRVERAIRHAIE) that forms the putative DNA recognition helix is particularly highly conserved, sugge sting a common DNA target. Insertional inactivation of spoOA in C. beijerin ckii blocked the formation of solvents las well as spores and granulose). S equences resembling SpoOA-binding motifs (TGNCGAA) are found in the promote r regions of several of the genes whose expression is modulated at the onse t of solventogenesis in Clostridium acetobutylicum and C. beijerinckii. The se include the upregulated ade gene, encoding acetoacetate decarboxylase (E C 4.1.1.4), and the downregulated ptb gene, encoding phosphotransbutyrylase (EC 2.3.1.c). In vitro gel retardation experiments using C. acetobutylicum ade and C. beijerinckii ptb promoter fragments and recombinant Bacillus su btilis and C. beijerinckii SpoOA suggested that ade and ptb are directly co ntrolled by SpoOA. The binding affinity was reduced when the OA boxes were destroyed, and enhanced when they were modified to conform precisely to the consensus sequence. In vivo analysis of wild-type and mutagenized promoter s transcriptionally fused to the gusA reporter gene in C. beijernickii vali dated this hypothesis. Postexponential phase expression from the mutagenize d ade promoter was substantially reduced, whereas expression from the mutag enized ptb promoter was not shut down at the end of exponential growth.