Identification and Characterization of Two Functionally Unknown Genes Involved in Butanol Tolerance of Clostridium acetobutylicum

Solvents toxicity is a major limiting factor hampering the cost-effective biotechnological production of chemicals. In Clostridium acetobutylicum, a functionally unknown protein (encoded by SMB_G1518) with a hypothetical alcohol interacting domain was identified. Disruption of SMB_G1518 and/or its downstream gene SMB_G1519 resulted in increased butanol tolerance, while overexpression of SMB_G1518-1519 decreased butanol tolerance. In addition, SMB_G1518-1519 also influences the production of pyruvate:ferredoxin oxidoreductase (PFOR) and flagellar protein hag, the maintenance of cell motility. We conclude that the system of SMB_G1518-1519 protein plays a role in the butanol sensitivity/tolerance phenotype of C. acetobutylicum, and can be considered as potential targets for engineering alcohol tolerance.溶剂毒性是制约化学品低成本生物技术生产的主要限制因素。本研究在丙酮丁醇梭菌（Clostridium acetobutylicum）中鉴定出一种功能未知的蛋白质（由SMB_G1518编码），其携带有假定醇相互作用结构域。敲除SMB_G1518及其下游基因SMB_G1519（或二者之一）可提升丁醇耐受性，而过表达SMB_G1518-1519则会降低丁醇耐受性。此外，SMB_G1518-1519还会影响丙酮酸铁氧还蛋白氧化还原酶（pyruvate:ferredoxin oxidoreductase，PFOR）与鞭毛蛋白Hag的表达，并参与细胞运动能力的维持。综上，SMB_G1518-1519蛋白质系统参与调控丙酮丁醇梭菌的丁醇敏感性/耐受性表型，可作为工程化改造醇类耐受性的潜在靶点。