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

The spo0A genes of Clostridium beijerinckii NCIMB 8052 and Clostridium cellulolyticum ATCC 35319 were isolated and characterized. The C‐terminal DNA‐binding domains of the predicted products of spo0A from these two organisms, as well as 16 other taxonomically diverse species of Bacillus and Clostrid...

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Bibliographic Details
Published in:Molecular microbiology 2000-09, Vol.37 (5), p.1172-1185
Main Authors: Ravagnani, Adriana, Jennert, Katrin C. B., Steiner, Elisabeth, Grünberg, Raik, Jefferies, James R., Wilkinson, Shane R., Young, Danielle I., Tidswell, Edward C., Brown, David P., Youngman, Philip, Morris, J. Gareth, Young, Michael
Format: Article
Language:English
Subjects:
acetoacetate decarboxylase
Acids
adc gene
Bacterial Proteins - genetics
Bacterial Proteins - metabolism
Base Sequence
Carboxy-Lyases - genetics
Clostridium - enzymology
Clostridium - genetics
Clostridium - metabolism
Clostridium acetobutylicum
Clostridium beijerinckii
Clostridium cellulolyticum
DNA, Bacterial
Gene Expression Regulation, Bacterial
Gene Expression Regulation, Enzymologic
Genes, Bacterial
Molecular Sequence Data
Phenotype
Phosphate Acetyltransferase - genetics
phosphotransbutyrylase
Promoter Regions, Genetic
ptb gene
Solvents
Spo0A protein
Spores, Bacterial
Transcription Factors - genetics
Transcription Factors - metabolism
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Summary:The spo0A genes of Clostridium beijerinckii NCIMB 8052 and Clostridium cellulolyticum ATCC 35319 were isolated and characterized. The C‐terminal DNA‐binding domains of the predicted products of spo0A from these two organisms, as well as 16 other taxonomically diverse species of Bacillus and Clostridium, show extensive amino acid sequence conservation (56% identity, 65% similarity over 104 residues). A 12‐amino‐acid motif (SRVERAIRHAIE) that forms the putative DNA recognition helix is particularly highly conserved, suggesting a common DNA target. Insertional inactivation of spo0A in C. beijerinckii blocked the formation of solvents (as well as spores and granulose). Sequences resembling Spo0A‐binding motifs (TGNCGAA) are found in the promoter regions of several of the genes whose expression is modulated at the onset of solventogenesis in Clostridium acetobutylicum and C. beijerinckii. These include the upregulated adc gene, encoding acetoacetate decarboxylase (EC 4.1.1.4), and the downregulated ptb gene, encoding phosphotransbutyrylase (EC 2.3.1.c). In vitro gel retardation experiments using C. acetobutylicum adc and C. beijerinckii ptb promoter fragments and recombinant Bacillus subtilis and C. beijerinckii Spo0A suggested that adc and ptb are directly controlled by Spo0A. The binding affinity was reduced when the 0A boxes were destroyed, and enhanced when they were modified to conform precisely to the consensus sequence. In vivo analysis of wild‐type and mutagenized promoters transcriptionally fused to the gusA reporter gene in C. beijerinckii validated this hypothesis. Post‐exponential phase expression from the mutagenized adc promoter was substantially reduced, whereas expression from the mutagenized ptb promoter was not shut down at the end of exponential growth.
ISSN:0950-382X
1365-2958
DOI:10.1046/j.1365-2958.2000.02071.x