title: Identification and Characterization of a Genestp17Located on the Linear Plasmid pBSSB1 as an Enhanced Gene of Growth and Motility inSalmonella entericaSerovar Typhi.
abstract: The linear plasmid pBSSB1 mediates the flagellar phase variation in H:z66 positiveSalmonella entericaserovar Typhi (S.Typhi). The gene namedstp17(S. Typhi plasmid number 17 gene) is located on pBSSB1 and encodes the protein STP17. The expression pattern at the protein-level and function of STP17 remains unknown. In this study, the recombinant protein STP17His6was expressed, purified and used to prepare the polyclonal anti-STP17 antibody. We detected protein-level expression ofstp17inS.Typhi and further investigated the protein expression characteristics ofstp17in different growth phases by western blot analysis. The effects of STP17 on bacterial growth and motility were analyzed. In addition, the structure of STP17 was predicted and the active site of STP17 was identified by site-directed mutagenesis. The results showed that STP17 was expressed stably in the wild type strain ofS. Typhi. STP17 expression at the protein level peaks when cultures reach an OD600value of 1.2. The growth rate and motility of the Δstp17strain were significantly decreased compared with the wild type strain (P< 0.05) and this phenotype was restored in thestp17complementary strain. Moreover, the growth rate and motility of thestp17over-expression strain was greater than the wild type strain. STP17 contains nine Helix segments, six Stand segments and some Coil segments in the secondary structural level. The top-ranked 3-D structure of STP17 predicted by I-TASSER contains a putative ATPase domain and the amino acid residues of GLY16, GLY19, LYS20, ASN133, LYS157, and LYS158 may be the active site residues of STP17. Finally, STP17 was able to catalyze the ATP to ADP reaction, suggesting that STP17 may be an ATPase. To our knowledge, this is the first report describing the protein expression characteristics of STP17 inS.Typhi, showing that STP17 promotes bacterial growth and motility, which may be associated with its potential ATPase activity.
authors.affiliation: Department of Clinical Laboratory, The Second Affiliated Hospital of Soochow UniversitySuzhou, China; School of Medicine, Jiangsu UniversityZhenjiang, China.
authors.forename: Haifang
authors.initials: H
authors.lastname: Zhang
authors.affiliation: School of Medicine, Jiangsu UniversityZhenjiang, China; Department of Clinical Laboratory, Shanghai East Hospital, School of Medicine, Tongji UniversityShanghai, China.
authors.forename: Yunxia
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: Department of Clinical Laboratory, The Second Affiliated Hospital of Soochow University Suzhou, China.
authors.forename: Xiaofang
authors.initials: X
authors.lastname: Xie
authors.affiliation: Department of Clinical Laboratory, The Second Affiliated Hospital of Soochow University Suzhou, China.
authors.forename: Min
authors.initials: M
authors.lastname: Wang
authors.affiliation: Department of Clinical Laboratory, The Second Affiliated Hospital of Soochow University Suzhou, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Du
authors.affiliation: School of Medicine, Jiangsu University Zhenjiang, China.
authors.forename: Shungao
authors.initials: S
authors.lastname: Xu
authors.affiliation: School of Medicine, Jiangsu University Zhenjiang, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: School of Medicine, Jiangsu University Zhenjiang, China.
authors.forename: Mingyu
authors.initials: M
authors.lastname: Gong
authors.affiliation: School of Medicine, Jiangsu University Zhenjiang, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Ni
authors.affiliation: School of Medicine, Jiangsu University Zhenjiang, China.
authors.forename: Huaxi
authors.initials: H
authors.lastname: Xu
authors.affiliation: School of Medicine, Jiangsu University Zhenjiang, China.
authors.forename: Xinxiang
authors.initials: X
authors.lastname: Huang
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D015153:Blotting, Western; D049109:Cell Proliferation; D019295:Computational Biology; D004252:DNA Mutational Analysis; D020869:Gene Expression Profiling; D005798:Genes, Bacterial; D008124:Locomotion; D008958:Models, Molecular; D010957:Plasmids; D011487:Protein Conformation; D012485:Salmonella typhi / Q000235:genetics* / Q000502:physiology*
chemical_list: D001426:Bacterial Proteins
keywords: ATPase; Salmonella enterica serovar Typhi; growth; linear plasmid; motility; pBSSB1; stp17