title: The CXC chemokine-degrading protease SpyCep of Streptococcus pyogenes promotes its uptake into endothelial cells.
abstract: Streptococcus pyogenes expresses the LPXTG motif-containing cell envelope serine protease SpyCep (also called ScpC, PrtS) that degrades and inactivates the major chemoattractant interleukin 8 (IL-8), thereby impairing host neutrophil recruitment. In this study, we identified a novel function of SpyCep: the ability to mediate uptake into primary human endothelial cells. SpyCep triggered its uptake into endothelial cells but not into human epithelial cells originating from pharynx or lung, indicating an endothelial cell-specific uptake mechanism. SpyCep mediated cellular invasion by an endosomal/lysosomal pathway distinct from the caveolae-mediated invasion pathway of S. pyogenes. Recombinant expression and purification of proteolytically active SpyCep and a series of subfragments allowed functional dissection of the domains responsible for endothelial cell invasion and IL-8 degradation. The N-terminal PR domain was sufficient to mediate endothelial cell invasion, whereas for IL-8-degrading activity, the protease domain and the flanking A domain were required. A polyclonal rabbit serum raised against the recombinant protease efficiently blocked the invasion-mediating activity of SpyCep but not its proteolytic function, further indicating that SpyCep-mediated internalization is independent from its enzymatic activity. SpyCep may thus specifically mediate its own uptake as secreted protein into human endothelial cells.
authors.affiliation: Department of Microbial Pathogenesis, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, D-38124 Braunschweig, Germany.
authors.forename: Simran Jeet
authors.initials: SJ
authors.lastname: Kaur
authors.forename: Andreas
authors.initials: A
authors.lastname: Nerlich
authors.forename: Simone
authors.initials: S
authors.lastname: Bergmann
authors.forename: Manfred
authors.initials: M
authors.lastname: Rohde
authors.forename: Marcus
authors.initials: M
authors.lastname: Fulde
authors.forename: Dorothea
authors.initials: D
authors.lastname: Zähner
authors.forename: Emanuel
authors.initials: E
authors.lastname: Hanski
authors.forename: Annelies
authors.initials: A
authors.lastname: Zinkernagel
authors.forename: Victor
authors.initials: V
authors.lastname: Nizet
authors.forename: Gursharan S
authors.initials: GS
authors.lastname: Chhatwal
authors.forename: Susanne R
authors.initials: SR
authors.lastname: Talay
mesh_terms: D000818:Animals; D000906:Antibodies / Q000276:immunology; D002460:Cell Line; D003001:Cloning, Molecular; D004705:Endocytosis; D011992:Endosomes / Q000378:metabolism; D042783:Endothelial Cells / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D016209:Interleukin-8 / Q000378:metabolism*; D008247:Lysosomes / Q000378:metabolism; D010447:Peptide Hydrolases / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D013297:Streptococcus pyogenes / Q000201:enzymology* / Q000235:genetics
chemical_list: D000906:Antibodies; D016209:Interleukin-8; D010447:Peptide Hydrolases; C527349:SpyCEP protein, Streptococcus pyogenes