title: The Staphylococcus aureus ArlRS two-component system is a novel regulator of agglutination and pathogenesis.
abstract: Staphylococcus aureus is a prominent bacterial pathogen that is known to agglutinate in the presence of human plasma to form stable clumps. There is increasing evidence that agglutination aids S. aureus pathogenesis, but the mechanisms of this process remain to be fully elucidated. To better define this process, we developed both tube based and flow cytometry methods to monitor clumping in the presence of extracellular matrix proteins. We discovered that the ArlRS two-component system regulates the agglutination mechanism during exposure to human plasma or fibrinogen. Using divergent S. aureus strains, we demonstrated that arlRS mutants are unable to agglutinate, and this phenotype can be complemented. We found that the ebh gene, encoding the Giant Staphylococcal Surface Protein (GSSP), was up-regulated in an arlRS mutant. By introducing an ebh complete deletion into an arlRS mutant, agglutination was restored. To assess whether GSSP is the primary effector, a constitutive promoter was inserted upstream of the ebh gene on the chromosome in a wildtype strain, which prevented clump formation and demonstrated that GSSP has a negative impact on the agglutination mechanism. Due to the parallels of agglutination with infective endocarditis development, we assessed the phenotype of an arlRS mutant in a rabbit combined model of sepsis and endocarditis. In this model the arlRS mutant displayed a large defect in vegetation formation and pathogenesis, and this phenotype was partially restored by removing GSSP. Altogether, we have discovered that the ArlRS system controls a novel mechanism through which S. aureus regulates agglutination and pathogenesis.
authors.affiliation: Department of Microbiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America.
authors.forename: Jennifer N
authors.initials: JN
authors.lastname: Walker
authors.affiliation: Department of Microbiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America.
authors.forename: Heidi A
authors.initials: HA
authors.lastname: Crosby
authors.affiliation: Department of Microbiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America.
authors.forename: Adam R
authors.initials: AR
authors.lastname: Spaulding
authors.affiliation: Department of Microbiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America.
authors.forename: Wilmara
authors.initials: W
authors.lastname: Salgado-Pabón
authors.affiliation: Department of Microbiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America.
authors.forename: Cheryl L
authors.initials: CL
authors.lastname: Malone
authors.affiliation: Department of Microbiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America.
authors.forename: Carolyn B
authors.initials: CB
authors.lastname: Rosenthal
authors.affiliation: Department of Microbiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America.
authors.forename: Patrick M
authors.initials: PM
authors.lastname: Schlievert
authors.affiliation: Department of Biochemistry and Microbiology, Rutgers University, New Brunswick, New Jersey, United States of America.
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Boyd
authors.affiliation: Department of Microbiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America.
authors.forename: Alexander R
authors.initials: AR
authors.lastname: Horswill
mesh_terms: D000371:Agglutination / Q000235:genetics; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology*; D002352:Carrier Proteins / Q000235:genetics; D004697:Endocarditis, Bacterial / Q000235:genetics / Q000382:microbiology; D005260:Female; D005340:Fibrinogen / Q000502:physiology; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D008297:Male; D030781:Organisms, Genetically Modified; D011817:Rabbits; D013203:Staphylococcal Infections / Q000235:genetics / Q000382:microbiology; D013211:Staphylococcus aureus / Q000235:genetics / Q000472:pathogenicity* / Q000502:physiology*
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; C469917:Ebh protein, Staphylococcus aureus; D005340:Fibrinogen