ISSN:
1432-1831
Keywords:
Key wordsStreptococcus pyogenes
;
vir regulon
;
Mga regulator
;
Cysteine protease
;
Oligopeptide permease
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract The vir regulon of group A streptococci (GAS) organizes the expression of several bacterial virulence factors under the control of the Mga regulator. Previously, the genes encoding the Mga regulator (mga), M and M-related proteins (emm, mrp, enn) and C5a peptidase (scpA) were reported to be clustered on the streptococcal genome in a core vir regulon. In the present study, the genomic regions of a serotype M49 strain upstream of mga and downstream of scpA were sequenced to assess the boundaries of the vir regulon. In the upstream region, an operon was identified that may be potentially involved in substrate transport and is independent from Mga regulation. In the downstream region, another Mga-controlled, scpA-cotranscribed gene was detected. This gene termed orfX encoded a 385-amino acid (aa) potential surface protein of unknown function. No binding of serum proteins to a recombinant ORFX was detectable and phagocytosis resistance of an orfX mutant remained unchanged. Downstream of orfX, another Mga-independent gene determined the 3′ end of the core vir regulon. Utilizing the M49 wild type, a mga – mutant and comparative Northern blot hybridization, genes encoding the capsule synthesis machinery, streptokinase and streptolysin O, as well as erythrogenic toxin A and DNase C were found to be Mga independent. In contrast, expression of the genes encoding the cysteine protease SpeB, streptococcin A and the oligopeptide permease was reduced in the mga – mutant. This indicated that in addition to the core vir regulon, Mga directly or indirectly controls a number of genes dispersed throughout the GAS genome.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s004300050028
Permalink
