title: Effects of MreB paralogs on poly-γ-glutamic acid synthesis and cell morphology in Bacillus amyloliquefaciens.
abstract: Actin-like MreB paralogs play important roles in cell shape maintenance, cell wall synthesis and the regulation of the D,L-endopeptidases, CwlO and LytE. The gram-positive bacteria, Bacillus amyloliquefaciens LL3, is a poly-γ-glutamic acid (γ-PGA) producing strain that contains three MreB paralogs: MreB, Mbl and MreBH. In B. amyloliquefaciens, CwlO and LytE can degrade γ-PGA. In this study, we aimed to test the hypothesis that modulating transcript levels of MreB paralogs would alter the synthesis and degradation of γ-PGA. The results showed that overexpression or inhibition of MreB, Mbl or MreBH had distinct effects on cell morphology and the molecular weight of the γ-PGA products. In fermentation medium, cells of mreB inhibition mutant were 50.2% longer than LL3, and the γ-PGA titer increased by 55.7%. However, changing the expression level of mbl showed only slight effects on the morphology, γ-PGA molecular weight and titer. In the mreBH inhibition mutant, γ-PGA production and its molecular weight increased by 56.7% and 19.4%, respectively. These results confirmed our hypothesis that suppressing the expression of MreB paralogs might reduce γ-PGA degradation, and that improving the cell size could strengthen γ-PGA synthesis. This is the first report of enhanced γ-PGA production via suppression of actin-like MreB paralogs.
authors.affiliation: Key Laboratory of Molecular Microbiology and Technology for Ministry of Education, Nankai University, Tianjin 300071, China.
authors.forename: Weixia
authors.initials: W
authors.lastname: Gao
authors.affiliation: Key Laboratory of Bioactive Materials for Ministry of Education, State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin 300071, China.
authors.forename: Zhongxiong
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Molecular Microbiology and Technology for Ministry of Education, Nankai University, Tianjin 300071, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Feng
authors.affiliation: Key Laboratory of Molecular Microbiology and Technology for Ministry of Education, Nankai University, Tianjin 300071, China.
authors.forename: Yulei
authors.initials: Y
authors.lastname: Dang
authors.affiliation: Key Laboratory of Molecular Microbiology and Technology for Ministry of Education, Nankai University, Tianjin 300071, China.
authors.forename: Yufen
authors.initials: Y
authors.lastname: Quan
authors.affiliation: Key Laboratory of Molecular Microbiology and Technology for Ministry of Education, Nankai University, Tianjin 300071, China.
authors.forename: Yanyan
authors.initials: Y
authors.lastname: Gu
authors.affiliation: Key Laboratory of Bioactive Materials for Ministry of Education, State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin 300071, China.
authors.forename: Shufang
authors.initials: S
authors.lastname: Wang
authors.affiliation: Key Laboratory of Molecular Microbiology and Technology for Ministry of Education, Nankai University, Tianjin 300071, China songcj@nankai.edu.cn.
authors.forename: Cunjiang
authors.initials: C
authors.lastname: Song
mesh_terms: D000069977:Bacillus amyloliquefaciens / Q000166:cytology* / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000235:genetics* / Q000378:metabolism; D005285:Fermentation; D017353:Gene Deletion; D011099:Polyglutamic Acid / Q000031:analogs & derivatives* / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D003598:Cytoskeletal Proteins; C511775:poly(gamma-glutamic acid); D011099:Polyglutamic Acid
keywords: Bacillus amyloliquefaciens; MreB paralog; cell morphology; poly-γ-glutamic acid; small regulatory RNAs (sRNAs)