Adherence and fibronectin binding are environmentally regulated in the group A streptococci

Abstract

The ability of the pathogenic Gram-positive bacterium Streptococcus pyogenes (group A streptococcus) to bind fibronectin and adhere to respiratory epithelial cells is dependent on a surface protein called protein F. In this study, we have examined the regulation of expression of protein F and have shown that it is environmentally regulated in response to alterations in atmosphere. In six recent clinical isolates expression of protein F was repressed during growth under reduced concentrations of O2. Expression in an anaerobic environment was induced by both superoxide-generating and redox-altering reagents. However, regulation did not involve mry, a gene that controls expression of several streptococcal surface proteins. Protein F was constitutively expressed in one of two laboratory-passaged strains analysed, and in a complementation analysis using an allele of the gene that encodes protein F (prtF) cloned from a regulated strain and expressed in a constitutive strain, the constitutive phenotype was shown to be dominant in trans. Regulation, as monitored by fusion of prtF to a promoterless chloramphenicol acetyltransferase gene, involved transcriptional control. Environmentally induced alterations in protein F expression affected the ability of the bacterium to adhere to epithelial cells, which suggests that the ability to regulate expression of protein F may be important during infection.

Analysis of the Transcriptome of Group A Streptococcus in Mouse Soft Tissue Infection

“…Information about stage 1 is based on an expanding body of work, 8,10,11,34,103 and our results support this information by combined early expression of Mga, Ihk/Irr, and FasBCA/X regulatory systems that promote evasion of immune and innate host defenses and enhance host cell contact through surface adhesin production. Down-regulation of the negative regulatory systems of PerR, CovR/S, and CrgR promote production of reactive oxygen species detoxifying enzymes, hyaluronic acid capsule, and antimicrobial peptide resistance mechanisms, respectively, 8,35,[103][104][105][106][107] and our soft tissue model demonstrates similar results. Interestingly, we have discovered that transcription of transport and central metabolism genes appears tailored to unique GAS environments where host glycopeptides and complex carbohydrates are available, including maltodextrins, but which must be used under acidic and hypoxic conditions.…”

Streptococcal Adhesion and Colonization

“…This might be significant in promoting initial adherence of cells to the pharynx or skin (VanHeyningen et al, 1993). Superoxide stress, under 02-limited conditions, also stimulates PrtFl expression (Gibson and Caparon, 1996).…”

Complete genome sequence of an M1 strain of Streptococcus pyogenes

“…As with other organisms, the presence of alternate transcription signals allows the streptococcus to respond to environmental changes (23,24). S. pyogenes encodes the genes for a number of stress-related proteins, which includes several proteases involved in the stress response and most of the highly conserved SOS regulon genes.…”

“…S. pyogenes contains a major factor [ 70 (rpoD)] as well as an identifiable minor factor (homolog of E ). The E (also known as 24 ) is one of the major factors necessary for transcription of heat-induced proteins in E. coli (20), and the homolog found in S. pyogenes may play a similar role when the organism encounters elevated temperatures in the host. Another putative factor is a homolog of the Streptococcus pneumoniae proposed factor com X that is a transcriptional regulator of competence-specific genes (21).…”