Journal of Bacteriology, October 1999, p. 6019-6027, Vol. 181, No. 19
0021-9193/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.

Department of Microbiology and Immunology, Medical College of Ohio, Toledo, Ohio 43614,1 and Abteilung für Medizinische Mikrobiologie, University Klinik Ulm, 89081 Ulm, Germany2
Received 18 March 1999/Accepted 22 July 1999
A Tn917 insertion mutant of an M49 serotype, opacity
factor-positive Streptococcus pyogenes, was isolated. It
had the following phenotypes: decreased
-hemolysis mediated by
streptolysin S, reduction in the activity of a secreted cysteine
protease and streptokinase, and an altered immunoglobulin and
fibrinogen-binding phenotype. The site of insertion of
Tn917 into the chromosome and the surrounding sequence, the
pel region (pleiotropic effect locus), was determined.
Phage A25 transduction confirmed that the pleiotropic changes in
phenotype could be cotransduced with Tn917. The
pel region was cloned and sequenced, and the transposon was
found to be inserted upstream of a single open reading frame which led
to a failure to transcribe a 500-base mRNA. The loss of this transcript
decreased the transcription of emm and speB genes and reduced the secretion of streptokinase. Enhanced Pel expression from a nisin-inducible plasmid resulted in increased message
levels for emm in a wild-type organism.
Characterization of the pel mutant provides evidence for
the coordinated regulation of secreted and surface proteins and
suggests the existence of a new global regulatory factor in S. pyogenes.
Present address: Laboratory of Pathology, National Cancer
Institute, Bethesda, MD 20892-1500.
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