Involvement of Lsp, a Member of the LraI-Lipoprotein Family inStreptococcus pyogenes, in Eukaryotic Cell Adhesion and Internalization

Abstract

Three open reading frames (ORFs) were identified by a genome walking strategy in the genomes of serotype M49 group A streptococcal (GAS) strains CS101 and 591. These ORFs were located between the mga core regulon and the dipeptide permease operon. The deduced amino acid (aa) sequences contained signature sequences indicative of a lipoprotein (306 aa), an intracellular protein (823 aa), and a secreted peptide (66 aa), respectively. ORF1 (named Lsp for lipoprotein of Streptococcus pyogenes) and ORF2 exhibited a high degree of homology to the lmb/ORF2 genes of S. agalactiae (B. Spellerberg et al., Infect. Immun. 67:871-878, 1999). The three ORFs were found to be present in each of the 27 GAS serotype strains tested. Transcription analysis revealed a polycistronic lsp/ORF2 and a monocistronic ORF3 message that were detected primarily at the transition from exponential to stationary growth phase. lsp and ORF2 mutants, ORF2-and ORF3-luciferase reporter fusions, and antiserum against recombinant Lsp were produced to examine the biological role of these genes. Although high Zn 2؉ and Cu 2؉ ion concentrations decreased lsp operon expression, Lsp did not transport divalent cations as described for other LraI-type operons. The lsp mutant had reduced fibronectin binding. Although no direct binding of Lsp to fibronectin could be demonstrated, the lsp mutant showed decreased transcription of prtF2 encoding the fibronectin-binding protein F2. Both the lsp and ORF2 mutants showed decreased laminin binding. Adherence to and internalization into A549 epithelial cells of both mutants was reduced without a detectable effect on eukaryotic cell viability. The transcription of a number of virulence factors was altered in the lsp mutants and ORF2 mutants. The changes in laminin binding and eukaryotic cell internalization could be explained by changes in transcription of speB (cysteine protease) and/or the global regulators mga, csrRS, and nra.

The Metal Homeostasis Protein, Lsp, of Streptococcus pyogenes Is Necessary for Acquisition of Zinc and Virulence

“…It has been previously reported that an Lsp-null mutant had a reduced ability to adhere to epithelial cells, suggesting that Lsp may act directly as an adhesin to recognize a host cell receptor (23). It was also noted that the Lsp Ϫ mutant had reduced expression of several virulence factors, including PrtFII, a fibronectin-binding adhesin (23).…”

“…Similar to the case for PsaA Ϫ mutants of S. pneumoniae (5, 71), Lsp Ϫ mutants of S. pyogenes have a defect in their ability to adhere to cultured host cells (23). However, subsequent analyses of PsaA Ϫ mutants have suggested that the adherence defect is an indirect result of an imbalance in metal homeostasis promoted by the loss of PsaA (43).…”

“…For example, the protein Lsp (23) was originally identified on the basis of its homology to a lamininbinding adhesin of Streptococcus agalactiae (79). Further, an Lsp mutant was found to have defective ability to adhere to epithelial cells (23). It was also recognized that Lsp had a high degree of similarity to PsaA of Streptococcus pneumoniae, a member of the cluster 9 family of ligand-binding components of the ATP-binding cassette (ABC-type) transporter superfamily (16,21).…”

Transcriptional regulation, occurrence and putative role of the Pht family of Streptococcus pneumoniae

“…Indeed, this protein shows similarities to an adhesin family known as LraI found initially in oral streptococci (Jenkinson, 1994) and since then discovered in other streptococci and other genera (Cockayne et al, 1998). It was suggested that LraI-like proteins are involved in the colonization of human epithelium by streptococci and their subsequent invasion into the bloodstream (Elsner et al, 2002). It is not clear why yfnA, lmb and phtD are associated in an operon system.…”

Involvement of Lipoprotein NlpI in the Virulence of Adherent Invasive Escherichia coli Strain LF82 Isolated from a Patient with Crohn's Disease

“…Finally, bacterial lipoproteins are also involved in adhesion to and invasion of epithelial cells (42). For example, the surface-exposed lipoprotein JlpA specific to Campylobacter jejuni mediates adherence to HEp-2 epithelial cells and Lsp, which belongs to the LraI lipoprotein family, is involved in Streptococcus pyogenes adhesion to and invasion of A549 cells (11,16).…”