Structure-guided study of the active sites of glyoxalase I from Zea mays

TURRA, GL.; AGOSTINI, RB.; FAUGUEL, CM.; ANDREO, CS.; GONZALEZ, JM.; CAMPOS BERMUDEZ, VA.

Congreso; LI Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biologia Molecular; 2015

The glyoxalase system is ubiquitous among all forms of life, due to its central role at relieving the cell from the accumulation of methylglyoxal, a toxic metabolic by-product. In higher plants, this system is up regulated under diverse metabolic stress conditions, such as defense response to infection by pathogenic microorganisms. Fusarium verticillioides is the most common pathogen of maize and we have observed that the expression of GLXI is upregulated in moderately resistant maize lines compared with susceptible ones. In this study, glyoxalase I from Zea mays has been characterized both biochemically and structurally, reporting the first atomic model of a GLXI available from plants. Our results show that this enzyme comprises a single polypeptide with two structurally similar domains, one of which harbors a functional Ni(II)-binding active site, as confirmed through site-directed mutagenesis. E144Q mutant abolished one of the amino acid residues involved in metal cofactor binding, allowing us to confirm that GLXI is a Ni(II)-dependent metalloenzyme. The putative function of the remaining cryptic active site is being evaluated through regeneration of the ability to bind metal by the V278E mutant.