Decoding Biomass-Sensing Regulons of Clostridium thermocellum Alternative Sigma-I Factors in a Heterologous Bacillus subtilis Host System.

摘要: The Gram-positive, anaerobic, cellulolytic, thermophile Clostridium (Ruminiclostridium) thermocellum secretes a multi-enzyme system called the cellulosome to solubilize plant cell wall polysaccharides. During saccharolytic process, enzymatic composition of is modulated according type polysaccharide(s) present in environment. C. has set eight alternative RNA polymerase sigma (σ) factors that are activated response extracellular polysaccharides and share sequence similarity Bacillus subtilis σI factor. aim work was demonstrate whether individual σI-like regulate specific cellulosomal genes, focusing on σI6 σI3 factors. To search for putative σI6- σI3-dependent promoters, bioinformatic analysis upstream regions genes performed. Because limited genetic tools available thermocellum, functionality predicted promoters studied B. as heterologous host. This enabled observation activation 10 σI6-dependent associated with genes: sigI6 (itself, Clo1313_2778), xyn11B (Clo1313_0522), xyn10D (Clo1313_0177), xyn10Z (Clo1313_2635), xyn10Y (Clo1313_1305), cel9V (Clo1313_0349), cseP (Clo1313_2188), sigI1 (Clo1313_2174), cipA (Clo1313_0627), rsgI5 (Clo1313_0985). Additionally, we observed 4 sigI3 Clo1313_1911), pl11 (Clo1313_1983), ce12 (Clo1313_0693) cipA. Our results suggest possible regulons well promoter consensus sequences. proposed -35 -10 elements CNNAAA CGAA, respectively. less conserved CGA next C element highly AT three bases downstream were also identified important nucleotides recognition. Regarding σI3, CCCYYAAA CGWA, study provides new clues understanding these recently discovered