title: The identification of four histidine kinases that influence sporulation in Clostridium thermocellum.
abstract: In this study, we sought to identify genes involved in the onset of spore formation in Clostridium thermocellum via targeted gene deletions, gene over-expression, and transcriptional analysis. We determined that three putative histidine kinases, clo1313_0286, clo1313_2735 and clo1313_1942 were positive regulators of sporulation, while a fourth kinase, clo1313_1973, acted as a negative regulator. Unlike Bacillus or other Clostridium species, the deletion of a single positively regulating kinase was sufficient to abolish sporulation in this organism. Sporulation could be restored in these asporogenous strains via overexpression of any one of the positive regulators, indicating a high level of redundancy between these kinases. In addition to having a sporulation defect, deletion of clo1313_2735 produced L-forms. Thus, this kinase may play an additional role in repressing L-form formation. This work suggests that C. thermocellum enters non-growth states based on the sensory input from multiple histidine kinases. The ability to control the development of non-growth states at the genetic level has the potential to inform strategies for improved strain development, as well as provide valuable insight into C. thermocellum biology.
authors.affiliation: Thayer School of Engineering, Dartmouth College, Hanover, NH 03755, USA; BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.
authors.forename: Elizabeth B
authors.initials: EB
authors.lastname: Mearls
authors.affiliation: Thayer School of Engineering, Dartmouth College, Hanover, NH 03755, USA; BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA. Electronic address: Lee.R.Lynd@dartmouth.edu.
authors.forename: Lee R
authors.initials: LR
authors.lastname: Lynd
mesh_terms: D048013:Acetivibrio thermocellus / Q000201:enzymology* / Q000235:genetics / Q000502:physiology*; D017353:Gene Deletion; D015870:Gene Expression; D020869:Gene Expression Profiling; D000071677:Histidine Kinase; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D013171:Spores, Bacterial / Q000254:growth & development*
chemical_list: D011494:Protein Kinases; D000071677:Histidine Kinase
keywords: Cellulose degradation; Histidine kinase; L-Forms; Metabolic shutdown; Sporulation