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Structure of Chit33 from Trichoderma harzianum.Structure of Chit33 from Trichoderma harzianum.
Structural highlights
FunctionCHI33_TRIHA Secreted chitinase involved in the degradation of chitin, a component of the cell walls of fungi and exoskeletal elements of some animals (including worms and arthropods). Plays a morphogenetic role during apical growth, cell division and differentiation (cell wall morphogenesis). May be involved in the degradation and further assimilation of phytopathogenic fungi, namely mycoparasitism, the major mechanism accounting for the antagonistic activity against phytopathogenic fungi displayed by Trichoderma.[1] Publication Abstract from PubMedChitin is the most widespread amino renewable carbohydrate polymer in nature and the second most abundant polysaccharide. Therefore, chitin and chitinolytic enzymes are becoming more importance for biotechnological applications in food, health and agricultural fields, the design of effective enzymes being a paramount issue. We report the crystal structure of the plant-type endo-chitinase Chit33 from Trichoderma harzianum and its D165A/E167A-Chit33-(NAG)4 complex, which showed an extended catalytic cleft with six binding subsites lined with many polar interactions. The major trait of Chit33 is the location of the non-conserved Asp117 and Arg274 acting as a clamp, fixing the distorted conformation of the sugar at subsite -1 and the bent shape of the substrate, which occupies the full catalytic groove. Relevant residues were selected for mutagenesis experiments, the variants being biochemically characterized through their hydrolytic activity against colloidal chitin and other polymeric substrates with different molecular weights and deacetylation percentages. The mutant S118Y stands out, showing a superior performance in all the substrates tested, as well as detectable transglycosylation capacity, with this variant providing a promising platform for generation of novel Chit33 variants with adjusted performance by further design of rational mutants'. The putative role of Tyr in binding was extrapolated from molecular dynamics simulation. Structure-Function Insights into the Fungal Endo-Chitinase Chit33 Depict its Mechanism on Chitinous Material.,Jimenez-Ortega E, Kidibule PE, Fernandez-Lobato M, Sanz-Aparicio J Int J Mol Sci. 2022 Jul 9;23(14). pii: ijms23147599. doi: 10.3390/ijms23147599. PMID:35886948[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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