title: The hyaluronate lyase of Staphylococcus aureus - a virulence factor?
abstract: The hyaluronate lyase (HL) gene of Staphylococcus aureus 8325-4 (hysA) was inactivated in vitro with the insertion of the erythromycin determinant, ermC, from plasmid pE194. The hysA : : ermC mutation was introduced into S. aureus via a temperature-sensitive shuttle vector, where it underwent homologous recombination with the wild-type (w.t.) allele. The insertion of ermC in the chromosomal hysA locus was confirmed by Southern blot hybridization and the loss of HL activity was demonstrated macroscopically by a plate assay. The importance of HL for pathogenicity was assessed by comparing the virulence of the HL(-) mutant strain to that of the w.t. in an established mouse abscess model of S. aureus infection. A significantly higher cell recovery was obtained from lesions infected with the w.t. strain compared to the lesions infected with the HL(-) strain (P =0.01). Although the lesion areas from both groups were not significantly different (P=0.9) they were of different morphology. A colorimetric assay was used to measure HL activity from culture supernatants of the S. aureus 8325-4 strains w.t., WA250 (agr) and PC1839 (sar) grown in a chemically defined medium. HL activity reached a maximum in the w.t. strain during mid-exponential phase (t=5 h) and while it showed a 16-fold decrease in the agr mutant it increased 35-fold in the sar mutant background. These results strongly suggest that HL is a virulence factor which is important in the early stages of subcutaneous infections.
authors.affiliation: School of Biochemistry and Microbiology, University of Leeds, Leeds LS2 9JT, UK.
authors.forename: George
authors.initials: G
authors.lastname: Makris
authors.affiliation: School of Biochemistry and Microbiology, University of Leeds, Leeds LS2 9JT, UK.
authors.forename: John D
authors.initials: JD
authors.lastname: Wright
authors.affiliation: School of Biochemistry and Microbiology, University of Leeds, Leeds LS2 9JT, UK.
authors.forename: Eileen
authors.initials: E
authors.lastname: Ingham
authors.affiliation: School of Biochemistry and Microbiology, University of Leeds, Leeds LS2 9JT, UK.
authors.forename: Keith T
authors.initials: KT
authors.lastname: Holland
mesh_terms: D000038:Abscess / Q000382:microbiology; D000818:Animals; D005260:Female; D015964:Gene Expression Regulation, Bacterial; D051379:Mice; D009154:Mutation; D011133:Polysaccharide-Lyases / Q000235:genetics / Q000378:metabolism*; D013203:Staphylococcal Infections / Q000382:microbiology / Q000503:physiopathology; D013211:Staphylococcus aureus / Q000201:enzymology* / Q000472:pathogenicity*; D014774:Virulence; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D037521:Virulence Factors; D011133:Polysaccharide-Lyases; C100002:hyaluronate lyase