4MCK

Crystal structure of Family GH19, Class IV chitinase from Zea mays

Summary for 4MCK

• Entry DOI: 10.2210/pdb4mck/pdb
• Related: 4MCL
• Descriptor: Chitinase (2 entities in total)
• Functional Keywords: hydrolase
• Biological source: Zea mays (maize)
• Total number of polymer chains: 1
• Total formula weight: 22029.66

Authors

Chaudet, M.M.,Rose, D.R. (deposition date: 2013-08-21, release date: 2014-03-05, Last modification date: 2024-11-06)

Primary citation

Chaudet, M.M.,Naumann, T.A.,Price, N.P.,Rose, D.R.
Crystallographic structure of ChitA, a glycoside hydrolase family 19, plant class IV chitinase from Zea mays.
Protein Sci., 23:586-593, 2014

PubMed Abstract: Maize ChitA chitinase is composed of a small, hevein-like domain attached to a carboxy-terminal chitinase domain. During fungal ear rot, the hevein-like domain is cleaved by secreted fungal proteases to produce truncated forms of ChitA. Here, we report a structural and biochemical characterization of truncated ChitA (ChitA ΔN), which lacks the hevein-like domain. ChitA ΔN and a mutant form (ChitA ΔN-EQ) were expressed and purified; enzyme assays showed that ChitA ΔN activity was comparable to the full-length enzyme. Mutation of Glu62 to Gln (ChitA ΔN-EQ) abolished chitinase activity without disrupting substrate binding, demonstrating that Glu62 is directly involved in catalysis. A crystal structure of ChitA ΔN-EQ provided strong support for key roles for Glu62, Arg177, and Glu165 in hydrolysis, and for Ser103 and Tyr106 in substrate binding. These findings demonstrate that the hevein-like domain is not needed for enzyme activity. Moreover, comparison of the crystal structure of this plant class IV chitinase with structures from larger class I and II enzymes suggest that class IV chitinases have evolved to accommodate shorter substrates.

PubMed: 24616181
DOI: 10.1002/pro.2437

Experimental method

X-RAY DIFFRACTION (1.5 Å)