title: Streptococcal collagen-like surface protein 1 promotes adhesion to the respiratory epithelial cell.
abstract: BACKGROUND
  Collagen-like surface proteins Scl1 and Scl2 on Streptococcus pyogenes contain contiguous Gly-X-X triplet amino acid motifs, the characteristic structure of human collagen. Although the potential role of Scl1 in adhesion has been studied, the conclusions may be affected by the use of different S. pyogenes strains and their carriages of various adhesins. To explore the bona fide nature of Scl1 in adherence to human epithelial cells without the potential interference of other streptococcal surface factors, we constructed a scl1 isogenic mutant from the Scl2-defective S. pyogenes strain and a Scl1-expressed Escherichia coli.
  
  
  RESULTS
  Loss of Scl1 in a Scl2-defective S. pyogenes strain dramatically decreased the adhesion of bacteria to HEp-2 human epithelial cells. Expression of Scl1 on the surface of the heterologous bacteria E. coli significantly increased adhesion to HEp-2. The increase in adhesion was nullified when Scl1-expressed E. coli was pre-incubated with proteases or antibodies against recombinant Scl1 (rScl1) protein. Treatment of HEp-2 cells with rScl protein or pronase drastically reduced the binding capability of Scl1-expressed E. coli. These findings suggest that the adhesion is mediated through Scl1 on bacterial surface and protein receptor(s) on epithelial cells. Further blocking of potential integrins revealed significant contributions of α2 and β1 integrins in Scl1-mediated binding to epithelial cells.
  
  
  CONCLUSIONS
  Together, these results underscore the importance of Scl1 in the virulence of S. pyogenes and implicate Scl1 as an adhesin during pathogenesis of streptococcal infection.
authors.affiliation: Graduate Institute of Clinical Medical Sciences, Chang Gung University, Taoyuan, Taiwan, ROC.
authors.forename: Shih-Ming
authors.initials: SM
authors.lastname: Chen
authors.forename: Yau-Sheng
authors.initials: YS
authors.lastname: Tsai
authors.forename: Chin-Ming
authors.initials: CM
authors.lastname: Wu
authors.forename: Shuen-Kuei
authors.initials: SK
authors.lastname: Liao
authors.forename: Ling-Chia
authors.initials: LC
authors.lastname: Wu
authors.forename: Cherng-Shyang
authors.initials: CS
authors.lastname: Chang
authors.forename: Ya-Hui
authors.initials: YH
authors.lastname: Liu
authors.forename: Pei-Jane
authors.initials: PJ
authors.lastname: Tsai
mesh_terms: D018829:Adhesins, Bacterial; D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D002460:Cell Line; D003094:Collagen / Q000235:genetics / Q000378:metabolism*; D004847:Epithelial Cells; D006801:Humans; D016023:Integrins / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D011485:Protein Binding; D012137:Respiratory System / Q000378:metabolism / Q000382:microbiology*; D013290:Streptococcal Infections / Q000378:metabolism / Q000382:microbiology*; D013297:Streptococcus pyogenes / Q000235:genetics / Q000502:physiology*
chemical_list: D018829:Adhesins, Bacterial; D001426:Bacterial Proteins; D016023:Integrins; C423454:Scl1 protein, Streptococcus; C423453:Scl2 protein, Streptococcus; D003094:Collagen