| Structural highlights
Function
CHIA_MAIZE Defense against chitin-containing fungal pathogens (PubMed:1551872, Ref.6). Hydrolyzes glycol chitin and tetra-N-acetylchitotetraose in vitro (PubMed:28328103). Its action is countered by fungal polyglycine hydrolases and fungalysin, that cleave the chitin-binding domain from the protein (PubMed:21453431, PubMed:24627966, PubMed:25966977, PubMed:35240278, PubMed:36762862, Ref.6).[1] [2] [3] [4] [5] [6] [7] [8]
Publication Abstract from PubMed
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 DeltaN), which lacks the hevein-like domain. ChitA DeltaN and a mutant form (ChitA DeltaN-EQ) were expressed and purified; enzyme assays showed that ChitA DeltaN activity was comparable to the full-length enzyme. Mutation of Glu62 to Gln (ChitA DeltaN-EQ) abolished chitinase activity without disrupting substrate binding, demonstrating that Glu62 is directly involved in catalysis. A crystal structure of ChitA DeltaN-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.
Crystallographic structure of ChitA, a glycoside hydrolase family 19, plant class IV chitinase from Zea mays.,Chaudet MM, Naumann TA, Price NP, Rose DR Protein Sci. 2014 Feb 6. doi: 10.1002/pro.2437. PMID:24616181[9]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
- ↑ Huynh QK, Hironaka CM, Levine EB, Smith CE, Borgmeyer JR, Shah DM. Antifungal proteins from plants. Purification, molecular cloning, and antifungal properties of chitinases from maize seed. J Biol Chem. 1992 Apr 5;267(10):6635-40. PMID:1551872
- ↑ Naumann TA. Modification of recombinant maize ChitA chitinase by fungal chitinase-modifying proteins. Mol Plant Pathol. 2011 May;12(4):365-72. PMID:21453431 doi:10.1111/j.1364-3703.2010.00677.x
- ↑ Naumann TA, Wicklow DT, Price NP. Polyglycine hydrolases secreted by Pleosporineae fungi that target the linker region of plant class IV chitinases. Biochem J. 2014 Jun 1;460(2):187-98. PMID:24627966 doi:10.1042/BJ20140268
- ↑ Naumann TA, Naldrett MJ, Ward TJ, Price NP. Polyglycine hydrolases: Fungal β-lactamase-like endoproteases that cleave polyglycine regions within plant class IV chitinases. Protein Sci. 2015 Jul;24(7):1147-57. PMID:25966977 doi:10.1002/pro.2705
- ↑ Volpicella M, Leoni C, Fanizza I, Distaso M, Leoni G, Farioli L, Naumann T, Pastorello E, Ceci LR. Characterization of maize chitinase-A, a tough allergenic molecule. Allergy. 2017 Sep;72(9):1423-1429. doi: 10.1111/all.13164. Epub 2017 May 11. PMID:28328103 doi:http://dx.doi.org/10.1111/all.13164
- ↑ Naumann TA, Sollenberger KG, Hao G. Production of selenomethionine labeled polyglycine hydrolases in Pichia pastoris. Protein Expr Purif. 2022 Jun;194:106076. PMID:35240278 doi:10.1016/j.pep.2022.106076
- ↑ Dowling NV, Naumann TA, Price NPJ, Rose DR. Crystal structure of a polyglycine hydrolase determined using a RoseTTAFold model. Acta Crystallogr D Struct Biol. 2023 Feb 1;79(Pt 2):168-176. PMID:36762862 doi:10.1107/S2059798323000311
- ↑ Chaudet MM, Naumann TA, Price NP, Rose DR. Crystallographic structure of ChitA, a glycoside hydrolase family 19, plant class IV chitinase from Zea mays. Protein Sci. 2014 Feb 6. doi: 10.1002/pro.2437. PMID:24616181 doi:http://dx.doi.org/10.1002/pro.2437
- ↑ Chaudet MM, Naumann TA, Price NP, Rose DR. Crystallographic structure of ChitA, a glycoside hydrolase family 19, plant class IV chitinase from Zea mays. Protein Sci. 2014 Feb 6. doi: 10.1002/pro.2437. PMID:24616181 doi:http://dx.doi.org/10.1002/pro.2437
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