Genetic organisation of the M protein region in human isolates of group C and G streptococci: two types of multigene regulator-like (mgrC) regions

Geyer, Angelika; Schmidt, Karl‐Hermann

doi:10.1007/pl00008665

Cited by 39 publications

(38 citation statements)

References 44 publications

(52 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Homologs of Mga have been identified for a number of streptococci, including DmgA/ MgrC of S. dysgalactiae and MgrA of S. pneumoniae. Similar to Mga, DmgA was shown to regulate transcription of the emm homolog demA and is responsive to CO 2 (183,623). MgrA represses the expression of PI-1 in S. pneumoniae (230) and was found to be essential for nasopharyngeal colonization of mice (224).…”

Section: Regulatorsmentioning

confidence: 96%

StreptococcusAdherence and Colonization

Nobbs

Lamont

Jenkinson

2009

Microbiol Mol Biol Rev

547

569

View full text Add to dashboard Cite

SUMMARY Streptococci readily colonize mucosal tissues in the nasopharynx; the respiratory, gastrointestinal, and genitourinary tracts; and the skin. Each ecological niche presents a series of challenges to successful colonization with which streptococci have to contend. Some species exist in equilibrium with their host, neither stimulating nor submitting to immune defenses mounted against them. Most are either opportunistic or true pathogens responsible for diseases such as pharyngitis, tooth decay, necrotizing fasciitis, infective endocarditis, and meningitis. Part of the success of streptococci as colonizers is attributable to the spectrum of proteins expressed on their surfaces. Adhesins enable interactions with salivary, serum, and extracellular matrix components; host cells; and other microbes. This is the essential first step to colonization, the development of complex communities, and possible invasion of host tissues. The majority of streptococcal adhesins are anchored to the cell wall via a C-terminal LPxTz motif. Other proteins may be surface anchored through N-terminal lipid modifications, while the mechanism of cell wall associations for others remains unclear. Collectively, these surface-bound proteins provide Streptococcus species with a “coat of many colors,” enabling multiple intimate contacts and interplays between the bacterial cell and the host. In vitro and in vivo studies have demonstrated direct roles for many streptococcal adhesins as colonization or virulence factors, making them attractive targets for therapeutic and preventive strategies against streptococcal infections. There is, therefore, much focus on applying increasingly advanced molecular techniques to determine the precise structures and functions of these proteins, and their regulatory pathways, so that more targeted approaches can be developed.

show abstract

Section: Regulatorsmentioning

confidence: 96%

StreptococcusAdherence and Colonization

Nobbs

Lamont

Jenkinson

2009

Microbiol Mol Biol Rev

547

569

View full text Add to dashboard Cite

show abstract

“…Using gene-specific primers, the relative chromosomal arrangements of ska (SPy1979), rel (SPy1981) and nrdI (SPy1984) were found to be similar for ALAB49 and SF370 (data not shown), unlike the gene order observed for some strains of Streptococcus dysgalactiae subsp. equisimilis (Geyer & Schmidt, 2000). emm genes are also transcribed monocistronically in several GAS strains that have multiple emm genes (Bessen & Fischetti, 1992 ;Podbielski et al, 1995 ;Yung & Hollingshead, 1996).…”

Section: Figmentioning

confidence: 99%

Roles of the plasminogen activator streptokinase and the plasminogen-associated M protein in an experimental model for streptococcal impetigo

et al. 2002

View full text Add to dashboard Cite

Primary infection by group A streptococci (GAS) takes place at either the throat or skin of the human host, often leading to pharyngitis or impetigo, respectively. Many GAS strains differ in their preference for throat and skin tissue sites. Previous epidemiological findings show that many of the strains displaying strong tropism for the skin have a high-affinity binding site for plasminogen, located within M protein (PAM), a prominent surface fibril. Plasminogen bound by PAM interacts with streptokinase, a plasminogen activator secreted by GAS, to yield bacterial-bound plasmin activity. In this study, PAM and streptokinase were tested for their roles in infection using an experimental model that closely mimics human impetigo. Inactivation of genes encoding either PAM or streptokinase led to a partial, but significant, loss of virulence in vivo, as measured by net growth of the bacteria and pathological alterations. The relative loss in virulence in vivo was greater for the streptokinase mutant than for the PAM mutant. However, the PAM mutant, but not the streptokinase mutant, displayed a partial loss in resistance to phagocytosis in vitro. The combined experimental and epidemiological data provide evidence that PAM and streptokinase play a key role in mediating skinspecific infection by GAS. In addition, secreted cysteine proteinase activity due to SpeB leads to degradation of streptokinase in stationary phase broth cultures. Since SpeB is also a determinant of tissue-specific GAS infection at the skin, direct interactions between these two proteolytic pathways may constitute an important pathogenic mechanism. An integrated model for superficial infection at the skin is presented.

show abstract

“…Two types of multigene regulator-like (mgrC) loci with an Mga (Emm protein)-like structure have been reported to occur in S. dysgalactiae subsp. equisimilis (5). The large-type mgrC locus contains five genes (nrd, mgc, emm, cpdB, and rel), whereas the small-type mgrC locus contains four genes (nrd, mgc, emm, and rel).…”

mentioning

confidence: 99%