title: Role of the two-component regulatory system arlRS in ica operon and aap positive but non-biofilm-forming Staphylococcus epidermidis isolates from hospitalized patients.
abstract: The ica operon and aap gene are important factors for Staphylococcus epidermidis biofilm formation. However, we found 15 out of 101 S. epidermidis strains isolated from patients had both the ica operon and the aap gene in the genome but could not form biofilms (ica(+)aap(+)/BF(-) isolates). Compared with standard strain RP62A, the 15 ica(+)aap(+)/BF(-) isolates had similar growth curves and initial attachment abilities, but had much lower apparent transcription levels of the icaA gene and significantly less production of polysaccharide intercellular adhesion (PIA). Furthermore, the expression of accumulation-associated protein in ica(+)aap(+)/BF(-) isolates was much weaker than in RP62A. The mRNA levels of icaADBC transcription-related regulatory genes, including icaR, sarA, rsbU, srrA, arlRS and luxS, were measured in the 15 ica(+)aap(+)/BF(-) clinical isolates. The mRNA levels of arlR and rsbU in all of the ica(+)aap(+)/BF(-) isolates were lower than in RP62A at 4 h. At 10 h, 14/15 of the isolates showed lower mRNA levels of arlR and rsbU than shown by RP62A. However, expression of sarA, luxS, srrA and icaR varied in different ica(+)aap(+)/BF(-) isolates. To further investigate the role of arlRS in biofilm formation, we analyzed icaA, sarA and rsbU transcription, PIA synthesis, Aap expression and biofilm formation in an arlRS deletion mutant of S. epidermidis strain 1457 and all were much less than in the wild type strain. This is consistent with the hypothesis that ArlRS may play an important role in regulating biofilm formation by the ica(+)aap(+)/BF(-)S. epidermidis clinical isolates and operate via both ica-dependent and Aap-dependent pathways.
authors.affiliation: Key Laboratory of Medical Molecular Virology of Ministries of Education and Health, Institute of Medical Microbiology and Institutes of Biomedical Sciences, Shanghai Medical College of Fudan University, 138 Yi Xue Yuan Road, Shanghai 200032, PR China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Wu
authors.affiliation: Key Laboratory of Medical Molecular Virology of Ministries of Education and Health, Institute of Medical Microbiology and Institutes of Biomedical Sciences, Shanghai Medical College of Fudan University, 138 Yi Xue Yuan Road, Shanghai 200032, PR China.
authors.forename: Jingran
authors.initials: J
authors.lastname: Liu
authors.affiliation: Key Laboratory of Medical Molecular Virology of Ministries of Education and Health, Institute of Medical Microbiology and Institutes of Biomedical Sciences, Shanghai Medical College of Fudan University, 138 Yi Xue Yuan Road, Shanghai 200032, PR China.
authors.forename: Juan
authors.initials: J
authors.lastname: Jiang
authors.affiliation: Key Laboratory of Medical Molecular Virology of Ministries of Education and Health, Institute of Medical Microbiology and Institutes of Biomedical Sciences, Shanghai Medical College of Fudan University, 138 Yi Xue Yuan Road, Shanghai 200032, PR China.
authors.forename: Jian
authors.initials: J
authors.lastname: Hu
authors.affiliation: Key Laboratory of Medical Molecular Virology of Ministries of Education and Health, Institute of Medical Microbiology and Institutes of Biomedical Sciences, Shanghai Medical College of Fudan University, 138 Yi Xue Yuan Road, Shanghai 200032, PR China.
authors.forename: Tao
authors.initials: T
authors.lastname: Xu
authors.affiliation: Key Laboratory of Medical Molecular Virology of Ministries of Education and Health, Institute of Medical Microbiology and Institutes of Biomedical Sciences, Shanghai Medical College of Fudan University, 138 Yi Xue Yuan Road, Shanghai 200032, PR China.
authors.forename: Jiaxue
authors.initials: J
authors.lastname: Wang
authors.affiliation: Key Laboratory of Medical Molecular Virology of Ministries of Education and Health, Institute of Medical Microbiology and Institutes of Biomedical Sciences, Shanghai Medical College of Fudan University, 138 Yi Xue Yuan Road, Shanghai 200032, PR China. Electronic address: dqu@shmu.edu.cn.
authors.forename: Di
authors.initials: D
authors.lastname: Qu
mesh_terms: D001422:Bacterial Adhesion; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D018441:Biofilms / Q000254:growth & development; D017353:Gene Deletion; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D006761:Hospitals; D006801:Humans; D009876:Operon; D011135:Polysaccharides, Bacterial / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics; D013203:Staphylococcal Infections / Q000382:microbiology*; D013212:Staphylococcus epidermidis / Q000235:genetics* / Q000254:growth & development / Q000302:isolation & purification / Q000502:physiology*; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D011135:Polysaccharides, Bacterial; D012333:RNA, Messenger
keywords: ArlRS; Biofilm; Regulatory factors; Staphylococcus epidermidis; aap; ica operon