Broad spectrum activity of a lectin-like bacterial serine protease family on human leukocytes

PLoS One. 2014 Sep 24;9(9):e107920. doi: 10.1371/journal.pone.0107920. eCollection 2014.

Abstract

The serine protease autotransporter from Enterobacteriaceae (SPATE) family, which number more than 25 proteases with apparent diverse functions, have been phylogenetically divided into two distinct classes, designated 1 and 2. We recently demonstrated that Pic and Tsh, two members of the class-2 SPATE family produced by intestinal and extraintestinal pathogenic E. coli, were able to cleave a number of O-glycosylated proteins on neutrophils and lymphocytes resulting in impaired leukocyte functions. Here we show that most members of the class-2 SPATE family have lectin-like properties and exhibit differential protease activity reliant on glycoprotein type and cell lineage. Protease activity was seen in virtually all tested O-glycosylated proteins including CD34, CD55, CD164, TIM1, TIM3, TIM4 and C1-INH. We also show that although SPATE proteins bound and cleaved glycoproteins more efficiently on granulocytes and monocytes, they also targeted glycoproteins on B, T and natural killer lymphocytes. Finally, we found that the characteristic domain-2 of class-2 SPATEs is not required for glycoprotease activity, but single amino acid mutations in Pic domain-1 to those residues naturally occurring in domain-1 of SepA, were sufficient to hamper Pic glycoprotease activity. This study shows that most class-2 SPATEs have redundant activities and suggest that they may function as immunomodulators at several levels of the immune system.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Cell Line
  • Cells, Cultured
  • Enterobacteriaceae / enzymology*
  • Enterobacteriaceae / genetics
  • Enterobacteriaceae / immunology
  • Enterobacteriaceae / physiology*
  • Enterobacteriaceae Infections / immunology*
  • Enterobacteriaceae Infections / metabolism
  • Glycoproteins / analysis
  • Glycoproteins / immunology
  • Glycoproteins / metabolism
  • Host-Pathogen Interactions*
  • Humans
  • Leukocytes / immunology
  • Leukocytes / metabolism
  • Leukocytes / microbiology*
  • Models, Molecular
  • Molecular Sequence Data
  • Phylogeny
  • Proteolysis
  • Sequence Alignment
  • Serine Proteases / analysis
  • Serine Proteases / genetics
  • Serine Proteases / immunology*
  • Serine Proteases / metabolism

Substances

  • Glycoproteins
  • Serine Proteases