Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 7/26/2015
Publication Date: 7/26/2015
Citation: Naumann, T.A., Price, N.P., Naldrett, M.J. 2015. Abundance of truncated and full-length ChitA and ChitB chitinases in healthy and diseased maize tissues [abstract]. Plant Proteomics.
Technical Abstract: Chitinase modifying proteins, cmps, are secreted fungal proteases that combat plant defenses by truncating plant class IV chitinases. We initially discovered that ChitA and ChitB, two plant class IV chitinases that are abundant in developing and mature kernels of corn, are truncated by cmps during ear rot. Truncation of ChitA and ChitB results from cleavage near the amino-terminus of the protein; three different types of proteases target different peptide bonds. Fungalysin metalloproteases cleave between a glycine-cysteine that is conserved throughout plant class IV chitinases. Polyglycine hydrolases cleave in a polyglcyine linker region that is common in plant class IV chitinases in the grass family. A third, unidentified protease, cleaves a bond in the chitin-binding domain. In order to advance this research, I would like to develop methods to quantitate levels of intact and truncated ChitA and ChitB in experimental samples, through targeted proteomics. As the interaction between cmps and plant chitinases appears to be universal, developed methods could also be adapted to other plants. As a secondary interest, I would like to use quantitative proteomics to search for new protein targets of cmps. For example, blast analysis identified a homolog of the Cochliobolus carbonum polyglycine hydrolase—which cleaves the polyglycine linker in maize ChitA—in the fungus Nectria haematococca. But plants susceptible to this fungus don’t have any polyglycine-containing chitinases. Maybe this fungal protease has evolved to target a different plant protein(s)?