Obtenção de uma quitinase mutante recombinante e avaliação da sua interferência no crescimento do fungo R. stolonifer
Abstract
Chitin is the second most abundant biopolymer in nature and
its structure is formed by N-acetyl-β-D-glucosamine units linked through β-1,4-
glycosidic bonds. Different organisms have chitin such as crustaceans, insects and
fungi. The enzymes that hydrolyze chitin, called chitinases, belong to the class of
glycosyl hydrolases and are produced by several organisms. Biotechnological
applications of chitinases include biocontrol of fungi and insects. The objective
of this work was to obtain a recombinant chitinase from the leaf-cutter ant Atta
sexdens (AsChtII-C4B1-1) and evaluate its interference with the growth of the
fungus Rhizopus stolonifer. AsChtII-C4B1-1 shows 99.8% identity with the
AsChtII-C4B1 enzyme and can therefore be considered isoforms. Both enzymes
present a catalytic domain for chitinase in a chitin-binding domain (CBM).
AsChtII-C4B1-1 shows greater activity at pH 6.0 and 600C. Against the colloidal
chitin substrate, the AsChtII-C4B1 enzyme shows greater activity, requiring
15.8% less AsChtII-C4B1 to release 1µmol of N-Ac than AsChtII-C4B1-1. The
two enzymes were able to interfere with the growth of R. stolonifer, an important
fungus in agriculture. AsChtII-C4B1 and AsChtII-C4B1-1 reduced 57% and 53%
growth, respectively. The 3D Model of the AsChtII-C4B1-1 enzyme suggests that
the sequential differences between the enzymes may be related to the different
optimal pH and temperature values found and also to the difference in biological
activity.
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