A new structural class of bacterial thioester domains reveals a slipknot topology

Protein Sci. 2018 Sep;27(9):1651-1660. doi: 10.1002/pro.3478. Epub 2018 Sep 25.


An increasing number of surface-associated proteins identified in Gram-positive bacteria are characterized by intramolecular cross-links in structurally conserved thioester, isopeptide, and ester domains (TIE proteins). Two classes of thioester domains (TEDs) have been predicted based on sequence with, to date, only representatives of Class I structurally characterized. Here, we present crystal structures of three Class II TEDs from Bacillus anthracis, vancomycin-resistant Staphylococcus aureus, and vancomycin-resistant Enterococcus faecium. These proteins are structurally distinct from Class I TEDs due to a β-sandwich domain that is inserted into the conserved TED fold to form a slipknot structure. Further, the B. anthracis TED domain is presented in the context of a full-length sortase-anchored protein structure (BaTIE). This provides insight into the three-dimensional arrangement of TIE proteins, which emerge as very abundant putative adhesins of Gram-positive bacteria.

Keywords: Bacillus anthracis; Enterococcus faecium; Staphylococcus aureus; TIE proteins; bacterial surface proteins; crystal structures; thioester domains.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacillus anthracis / chemistry
  • Bacterial Proteins / chemistry*
  • Esters / chemistry*
  • Models, Molecular
  • Protein Conformation
  • Staphylococcus aureus / chemistry
  • Sulfur Compounds / chemistry*
  • Vancomycin-Resistant Enterococci / chemistry


  • Bacterial Proteins
  • Esters
  • Sulfur Compounds