title: Overexpression of specific proton motive force-dependent transporters facilitate the export of surfactin in Bacillus subtilis.
abstract: A novel surfactin producer, Bacillus subtilis THY-7, was isolated from soil. Using liposomes and transmembrane transport inhibitors, the surfactin efflux in THY-7 was determined to be mainly dependent on proton motive force (PMF), not ATP hydrolysis. YcxA, KrsE and YerP, three putative lipopeptide transporters with PMF as energy source, were then highlighted in this work. A mutant YcxA named as YcxAmt, with 2 transmembrane helices deletion due to a code-shift mutation of the encoding gene, was identified in THY-7. This truncated YcxAmt was confirmed unable to transfer surfactin; on the contrary, overexpression of the natural full-lengthYcxA enhanced the secretion of surfactin by 89 %. KrsE, a putative kurstakin transporter, was found also capable of transporting surfactin. Overexpression of KrsE increased the production of surfactin by 52 %. In the culture of YerP-overexpressing strain at 24 h, surfactin titer reached 1.58 g L(-1), which was 145 % higher than that of the control. This indicated that YerP acted as the major surfactin exporter in B. subtilis THY-7.
authors.affiliation: Key Laboratory for Industrial Biocatalysis, Ministry of Education, Department of Chemical Engineering, Tsinghua University, 100084, Beijing, China.
authors.forename: Xu
authors.initials: X
authors.lastname: Li
authors.forename: Huan
authors.initials: H
authors.lastname: Yang
authors.forename: Donglai
authors.initials: D
authors.lastname: Zhang
authors.forename: Xue
authors.initials: X
authors.lastname: Li
authors.forename: Huimin
authors.initials: H
authors.lastname: Yu
authors.forename: Zhongyao
authors.initials: Z
authors.lastname: Shen
mesh_terms: D000595:Amino Acid Sequence; D001412:Bacillus subtilis / Q000235:genetics* / Q000378:metabolism; D001413:Bacillus thuringiensis / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000235:genetics; D005285:Fermentation; D015964:Gene Expression Regulation, Bacterial; D055666:Lipopeptides / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D018892:Proton-Motive Force / Q000235:genetics*; D017422:Sequence Analysis, DNA; D012988:Soil Microbiology; D013501:Surface-Active Agents / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D055666:Lipopeptides; D026901:Membrane Transport Proteins; D013501:Surface-Active Agents