title: Polyphosphate kinase of Lysinibacillus sphaericus and its effects on accumulation of polyphosphate and bacterial growth.
abstract: Lysinibacillus sphaericus produces parasporal crystal proteins (Bin toxins) that are specifically toxic to Culex and Anopheles mosquito larvae. It has long persistence in mosquito breeding sites due to the recycle of spores in mosquito cadaver and certain environments. This bacterium is unable to metabolize sugar (except N-acetylglucosamine) but can use proteinaceous materials. Previous studies have shown that inorganic polyphosphate (polyP) is essential for cell growth and responses to nutritional stringencies and environmental stresses and branched-chain amino acids (BCAAs) are useful intracellular signals for bacterial adaption to nutritional environments. However, relatively little is known about the role of polyP and the regulation link between polyP and BCAAs in nutritional limitation adaptation in a bacterium incapable of polysaccharide utilization. Here, a primary enzyme involved in polyP biosynthesis, polyphosphate kinase (PPK), was identified from L. sphaericus, and the polyP accumulation in different nutritional media was investigated. Furthermore, a ppk null mutant and the ppk-complemented strain were constructed and the effect of deletion on cell growth, polyP accumulation and expression of BCAAs biosynthetic genes (ilvBHC) was surveyed. The result showed that deletion of ppk resulted in a deficiency in polyP accumulation rather than cell growth in Luria-Bertani (LB) medium. Further studies demonstrated that the cell growth was evidently retarded and the ilvBHC expression was significantly reduced when ppk mutant was transferred from LB to limited-amino acid (LA) medium and that these phenotypes were significantly restored in the ppk-complemented strain. These results suggested that PPK plays a role in polyP accumulation and expression of genes involved in BCAAs biosynthesis, providing a hint for further understanding of the role of PPK in nutritional limitation in L. sphaericus.
authors.affiliation: Key Laboratory of Agricultural and Environmental Microbiology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, People's Republic of China; University of Chinese Academy of Sciences, Beijing 100039, People's Republic of China. Electronic address: shitingyu198@126.com.
authors.forename: Tingyu
authors.initials: T
authors.lastname: Shi
authors.affiliation: Key Laboratory of Agricultural and Environmental Microbiology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, People's Republic of China; University of Chinese Academy of Sciences, Beijing 100039, People's Republic of China. Electronic address: ge_yong_@126.com.
authors.forename: Yong
authors.initials: Y
authors.lastname: Ge
authors.affiliation: Key Laboratory of Agricultural and Environmental Microbiology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, People's Republic of China; University of Chinese Academy of Sciences, Beijing 100039, People's Republic of China. Electronic address: zhni1985@163.com.
authors.forename: Ni
authors.initials: N
authors.lastname: Zhao
authors.affiliation: Key Laboratory of Agricultural and Environmental Microbiology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, People's Republic of China. Electronic address: huxm@wh.iov.cn.
authors.forename: Xiaomin
authors.initials: X
authors.lastname: Hu
authors.affiliation: Key Laboratory of Agricultural and Environmental Microbiology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, People's Republic of China. Electronic address: yzm@wh.iov.cn.
authors.forename: Zhiming
authors.initials: Z
authors.lastname: Yuan
mesh_terms: D000597:Amino Acids, Branched-Chain / Q000378:metabolism; D001406:Bacillaceae / Q000201:enzymology* / Q000254:growth & development* / Q000378:metabolism; D003470:Culture Media / Q000737:chemistry; D017353:Gene Deletion; D020869:Gene Expression Profiling; D005816:Genetic Complementation Test; D017856:Phosphotransferases (Phosphate Group Acceptor) / Q000378:metabolism*; D011122:Polyphosphates / Q000378:metabolism*
chemical_list: D000597:Amino Acids, Branched-Chain; D003470:Culture Media; D011122:Polyphosphates; D017856:Phosphotransferases (Phosphate Group Acceptor); C022424:polyphosphate kinase
keywords: Lysinibacillus sphaericus; Nutritional limitation; Polyphosphate; Polyphosphate kinase