Inhibition of polygylcine hydrolases by substrate analog peptides

Authors: Naumann, Todd; CHAUDET, MARCIA - University Of Waterloo; ROSE, DAVID - University Of Waterloo; Price, Neil

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 11/2/2017
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Polyglycine hydrolases are proteases secreted by fungal pathogens that target corn defense chitinases. They cleave interdomain glycine-glycine bonds within a polyglycine linker, separating substrate chitinases into two single domain proteins. Polyglycine hydrolases consist of 640 amino acids with a predicted beta-lactamase (family S12 protease) region of 280 amino acids. The remaining 60% of the amino acid sequence is unique. Both proteases and substrates can be produced recombinantly, and in-vitro assays can be analyzed by SDS-PAGE and MALDI-TOF MS. The current work improves our understanding of how these proteases recognize plant chitinases. This was accomplished by testing a library of substrate analog peptides to identify substrates and inhibitors. The results demonstrate that polyglycine hydrolases have limited active site specificity, only requiring a single glycine on the amino side of the scissile bond. Additionally, a substrate alpha helix on the carboxy side of the polyglycine linker was found to be important for recognition. A peptide that resembles this alpha helix was found to be the best protease inhibitor. The results suggest that plant defenses could be improved through in vivo expression of peptides that mimic this chitinase alpha helix.