title: The Staphylococcus epidermidis gdpS regulates biofilm formation independently of its protein-coding function.
abstract: The second messenger cyclic di-guanylate (c-di-GMP) plays an important role in controlling the switch between planktonic and biofilm lifestyles. The synthesis of c-di-GMP is catalyzed by di-guanylate cyclases (DGCs) and the enzymes are characterized by the presence of a conserved GGDEF domain. In the sequenced staphylococcal genomes, gdpS is the only gene encoding a GGDEF domain-containing protein. Previous studies have shown that gdpS contributes to staphylococcal biofilm formation, but its effect remains under debate. In the present study, we deleted gdpS in Staphylococcus epidermidis strain RP62A. Disruption of gdpS in this strain impaired biofilm formation under both static and dynamic flow conditions, suggesting that gdpS act as a positive regulator of biofilm development in this high-biofilm-forming isolate. The predicted translational start site of gdpS in S. epidermidis differs between the Refseq database and the Genbank database. By using site-directed mutagenesis and Western blot analysis, we determined GdpS is translated from the start codon annotated in the Refseq database. In addition, mutation in the GGDEF domain did not affect the ability of gdpS to complement the biofilm defect of the gdpS mutant. Heterologous di-guanylate cyclases expressed in trans failed to complement the gdpS mutant. These results confirmed that gdpS modulates staphylococcal biofilm independently of c-di-GMP signaling pathway. Furthermore, mutations of the start codon did not abolish the capacity of gdpS to enhance biofilm formation. Taken together, these findings indicated that the S. epidermidis gdpS regulates biofilm formation independently of its protein-coding function.
authors.affiliation: Department of Preclinical Medicine, Wannan Medical College, Wuhu 241002, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Zhu
authors.affiliation: Department of Laboratory Medicine, The Second Affiliated Hospital of Nanjing Medical University, Nanjing 210011, China.
authors.forename: Yanfeng
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: Key Laboratory of Medical Molecular Virology, Ministry of Education and Health, Fudan University, Shanghai 200032, China. Electronic address: yangwu@fudan.edu.cn.
authors.forename: Yang
authors.initials: Y
authors.lastname: Wu
authors.affiliation: Key Laboratory of Medical Molecular Virology, Ministry of Education and Health, Fudan University, Shanghai 200032, China. Electronic address: dqu@fudan.edu.cn.
authors.forename: Di
authors.initials: D
authors.lastname: Qu
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D018441:Biofilms / Q000254:growth & development*; D015153:Blotting, Western / Q000379:methods; D006152:Cyclic GMP / Q000031:analogs & derivatives* / Q000235:genetics / Q000378:metabolism; D004269:DNA, Bacterial / Q000235:genetics / Q000302:isolation & purification; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D005816:Genetic Complementation Test; D016297:Mutagenesis, Site-Directed / Q000379:methods; D013212:Staphylococcus epidermidis / Q000201:enzymology / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D014157:Transcription Factors; C062025:bis(3',5')-cyclic diguanylic acid; D006152:Cyclic GMP