title: The extracellular protein regulator (xpr) affects exoprotein and agr mRNA levels in Staphylococcus aureus.
abstract: xpr, a regulatory element of exoprotein synthesis in Staphylococcus aureus, defined by an insertion of Tn551 into the chromosome of strain S6C, affects the expression of several exoproteins at the mRNA level. Drastic reduction in transcript levels for staphylococcal enterotoxin B (seb), lipase (geh), alpha-toxin (hla), and delta-toxin (hld) were detected, while mRNA levels for coagulase (coa) and protein A (spa) were elevated. Because the delta-toxin gene resides within the RNAIII transcript of the exoprotein regulator, agr, the reduction in hld message in the mutant strain of S6C is indicative of additional regulatory events in exoprotein gene expression. Northern (RNA) analysis of total cellular RNA hybridized with probes specific for RNAII and RNAIII (the two major transcripts of the agr operon) showed that both transcripts were reduced 16- to 32-fold at 3 h (late exponential phase) and 8- to 16-fold at 12 h (postexponential phase). These data confirm our original findings (M. S. Smeltzer, M. E. Hart, and J. J. Iandolo, Infect. Immun. 61:919-925, 1993) that two regulatory loci, agr and xpr, are interactive at the genotypic level.
authors.affiliation: Department of Pathology and Microbiology, College of Veterinary Medicine, Kansas State University, Manhattan 66506.
authors.forename: M E
authors.initials: ME
authors.lastname: Hart
authors.forename: M S
authors.initials: MS
authors.lastname: Smeltzer
authors.forename: J J
authors.initials: JJ
authors.lastname: Iandolo
mesh_terms: D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000235:genetics; D001483:Base Sequence; D015152:Blotting, Northern; D002876:Chromosomes, Bacterial; D017931:DNA Primers; D004251:DNA Transposable Elements; D015964:Gene Expression Regulation, Bacterial; D015971:Gene Expression Regulation, Enzymologic; D005838:Genotype; D007700:Kinetics; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D009876:Operon; D016133:Polymerase Chain Reaction; D012329:RNA, Bacterial / Q000302:isolation & purification / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis / Q000378:metabolism*; D012045:Regulatory Sequences, Nucleic Acid; D013211:Staphylococcus aureus / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D017931:DNA Primers; D004251:DNA Transposable Elements; D012329:RNA, Bacterial; D012333:RNA, Messenger