Engineering the cytokinin-glucoside specificity of the maize beta-D-glucosidase Zm-p60.1 using site-directed random mutagenesis

Logo poskytovatele

Varování

Publikace nespadá pod Ekonomicko-správní fakultu, ale pod Středoevropský technologický institut. Oficiální stránka publikace je na webu muni.cz.
Autoři

FILIPI Tomáš MAZURA Pavel JANDA Lubomír KIRAN Nagavalli Subbanna BRZOBOHATÝ Břetislav

Rok publikování 2012
Druh Článek v odborném periodiku
Časopis / Zdroj Phytochemistry
Fakulta / Pracoviště MU

Středoevropský technologický institut

Citace
Doi http://dx.doi.org/10.1016/j.phytochem.2011.10.008
Obor Biochemie
Klíčová slova (alpha/beta)(8) Barrel; beta-Glucosidase; cis-Zeatin-O-beta-D-glucopyranoside; Cytokinin metabolism; Glycosidase; Protein engineering; Site-directed random mutagenesis; Substrate specificity; trans-Zeatin-O-beta-D-glucopyranoside; trans-Zeatin-9-beta-D-glucopyranoside
Popis The maize beta-D-glucosidase Zm-p60.1 releases active cytokinins from their storage/transport forms, and its over-expression in tobacco disrupts zeatin metabolism. The role of the active-site microenvironment in fine-tuning Zm-p60.1 substrate specificity has been explored, particularly in the W373K mutant, using site-directed random mutagenesis to investigate the influence of amino acid changes around the 373 position. Two triple (P372T/W373K/M376L and P372S/W373K/M376L) and three double mutants (P372T/W373K, P372S/W373K and W373K/M376L) were prepared. Their catalytic parameters with two artificial substrates show tight interdependence between substrate catalysis and protein structure. P372T/W373K/M376L exhibited the most significant effect on natural substrate specificity: the ratio of hydrolysis of cis-zeatin-O-beta-D-glucopyranoside versus the trans-zeatin-O-beta-D-glucopyranoside shifted from 1.3 in wild-type to 9.4 in favor of the cis- isomer. The P372T and M376L mutations in P372T/W373K/M376L also significantly restored the hydrolytic velocity of the W373K mutant, up to 60% of wild-type velocity with cis-zeatin-O-beta-D-glucopyranoside. These findings reveal complex relationships among amino acid residues that modulate substrate specificity and show the utility of site-directed random mutagenesis for changing and/or fine-tuning enzymes. Preferential cleavage of specific isomer-conjugates and the capacity to manipulate such preferences will allow the development of powerful tools for detailed probing and fine-tuning of cytokinin metabolism in planta. (C) 2011 Elsevier Ltd. All rights reserved.
Související projekty:

Používáte starou verzi internetového prohlížeče. Doporučujeme aktualizovat Váš prohlížeč na nejnovější verzi.