PMID:21421765

Citation	Jones, SW, Tracy, BP, Gaida, SM and Papoutsakis, ET (2011) Inactivation of σF in Clostridium acetobutylicum ATCC 824 blocks sporulation prior to asymmetric division and abolishes σE and σG protein expression but does not block solvent formation. J. Bacteriol. 193:2429-40
Abstract	Clostridium acetobutylicum is both a model organism for the understanding of sporulation in solventogenic clostridia and its relationship to solvent formation and an industrial organism for anaerobic acetone-butanol-ethanol (ABE) fermentation. How solvent production is coupled to endospore formation--both stationary-phase events--remains incompletely understood at the molecular level. Specifically, it is unclear how sporulation-specific sigma factors affect solvent formation. Here the sigF gene in C. acetobutylicum was successfully disrupted and silenced. Not only σ(F) but also the sigma factors σ(E) and σ(G) were not detected in the sigF mutant (FKO1), and differentiation was stopped prior to asymmetric division. Since plasmid expression of the spoIIA operon (spoIIAA-spoIIAB-sigF) failed to complement FKO1, the operon was integrated into the FKO1 chromosome to generate strain FKO1-C. In FKO1-C, σ(F) expression was restored along with sporulation and σ(E) and σ(G) protein expression. Quantitative reverse transcription-PCR (RT-PCR) analysis of a select set of genes (csfB, gpr, spoIIP, sigG, lonB, and spoIIR) that could be controlled by σ(F), based on the Bacillus subtilis model, indicated that sigG may be under the control of σ(F), but spoIIR, an important activator of σ(E) in B. subtilis, is not, and neither are the rest of the genes investigated. FKO1 produced solvents at a level similar to that of the parent strain, but solvent levels were dependent on the physiological state of the inoculum. Finally, the complementation strain FKO1-C is the first reported instance of purposeful integration of multiple functional genes into a clostridial chromosome--here, the C. acetobutylicum chromosome--with the aim of altering cell metabolism and differentiation.
Links	PubMed PMC3133174 Online version:10.1128/JB.00088-11
Keywords	Acetone/metabolism; Butanols/metabolism; Clostridium acetobutylicum/genetics; Clostridium acetobutylicum/growth & development; Clostridium acetobutylicum/metabolism; Gene Expression Regulation, Bacterial; Gene Knockout Techniques; Genetic Complementation Test; Sigma Factor/genetics; Sigma Factor/metabolism; Spores, Bacterial/genetics; Spores, Bacterial/growth & development
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
CLOAB:Q97TE7		GO:0016987: sigma factor activity	ECO:0000315:		F		Figure 4: Expression of all three sigma factors is restored in the complemented strain FKO1-C (Fig. 4), confirming that a functional σF restores σE and σG expression	complete CACAO 10060

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