Structural Basis for Nanomolar-Affinity Inhibition of Neutrophil Serine Protease Activity by the S. aureus EAP Domain Protein, Eap1.

Extracellular adherence domain proteins (EAP) are a novel class of innate immune evasion molecules secreted by the human pathogen, Staphylococcus aureus. EAP domains are potent and selective inhibitors of neutrophil elastase (NE) and cathepsin-G (CG), which are the two most abundant neutrophil serine proteases (NSPs). Previous work from our group has shown that the prototypical EAP domain protein, EapH1, relies on structural plasticity of a single inhibitory site to block activity of NE and CG. However, whether other EAP domain proteins follow similar structure/function relationships remains unknown. To address this limitation, we studied herein the inhibitory properties of Eap1 and determined its structure both free and bound to either NE and CG. Eap1 displayed both dose-dependent inhibition of NE and CG with Ki values of 0.24 nM +/- 0.1 and 8.5 nM +/- 1.2, respectively. The structure of EAP1 determined at 1.45 A limiting resolution adopted a compact, b-grasp fold typical of ~100 residue EAP domain proteins. Whereas the structure of Eap1 bound to CG and determined at 1.95 A revealed an overall inhibitory pose similar to that seen for EapH1, the structure of Eap1 bound to NE and determined at 2.20 A surprisingly showed an inhibitory pose involving a distal region of the EAP domain. Although EAP domains share high levels of sequence and structural homology to one another, our work demonstrates that these high-affinity inhibitors are capable for forming structurally divergent complexes with two target proteases that themselves share high levels of sequence and structural homology one another. © FASEB.

Citation

Carson D Gido. Structural Basis for Nanomolar-Affinity Inhibition of Neutrophil Serine Protease Activity by the S. aureus EAP Domain Protein, Eap1. FASEB journal : official publication of the Federation of American Societies for Experimental Biology. 2022 May;36 Suppl 1

PMID: 35554135

search → result