ApuA, a multifunctional x-glucan-degrading enzyme of Streptococcus suis, mediates adhesion to porcine epithelium and mucus

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We have identified apuA in Streptococcus suis, which encodes a bifunctional amylopullulanase with conserved -amylase and pullulanase substrate-binding domains and catalytic motifs. ApuA exhibited properties typical of a Gram-positive surface protein, with a putative signal sequence and LPKTGE cell-wall-anchoring motif. A recombinant protein containing the predicted N-terminal -amylase domain of ApuA was shown to have -(1,4) glycosidic activity. Additionally, an apuA mutant of S. suis lacked the pullulanase -(1,6) glycosidic activity detected in a cell-surface protein extract of wild-type S. suis. ApuA was required for normal growth in complex medium containing pullulan as the major carbon source, suggesting that this enzyme plays a role in nutrient acquisition in vivo via the degradation of glycogen and food-derived starch in the nasopharyngeal and oral cavities. ApuA was shown to promote adhesion to porcine epithelium and mucus in vitro, highlighting a link between carbohydrate utilization and the ability of S. suis to colonize and infect the host.
Original languageEnglish
Pages (from-to)2818-2828
Publication statusPublished - 2010



  • group-a streptococcus
  • gram-positive bacteria
  • toxic-shock-syndrome
  • germ-free pigs
  • actinobacillus-actinomycetemcomitans
  • nasopharyngeal colonization
  • molecular characterization
  • staphylococcus-aureus
  • vaccine development
  • gene inactivation

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