Date of Award

Fall 2023

Document Type

Open Access Dissertation

Department

Chemistry and Biochemistry

First Advisor

Maksymilian Chruszcz

Abstract

The two-spotted spider mite, Tetranychus urticae, is a major cosmopolitan pest that feeds on more than 1,100 plant species, including 150 crops. Such a wide host range indicates this mite’s unparalleled xenobiotic responsiveness that is also coincident with their ability to rapidly develop resistance to pesticides. An unprecedently large detoxifying machinery is one of the main biological traits responsible for their extraordinary adaptation potential and devastating effect on crops. Availability of the whole genome sequence revealed expansions in all major detoxifying families and demonstrated that this genome has been enriched by horizontally transferred genes from bacteria and fungi. Motivated by the need to find novel ways to manage this pest, structural, functional, and biochemical studies are performed on biologically relevant enzymes belonging to three main detoxification families. First, the molecular basis of substrate promiscuity of a uridine diphosphate (UDP)- glycosyltransferase (UGT), that plays a role in mite adaptation to tomato plants, is elucidated. Secondly, two close homologous Mu-class glutathione S-transferases (TuGSTm), a class thought to be vertebrate specific, were structurally and functionally characterized. Additionally, spider mite neutralization of the glucosinolate–myrosinase plant defense system during its adaptation to Arabidopsis was dissected. Third, a novel dimerization mechanism in the intradiol-ring cleavage dioxygenase (IDRCD) family of enzymes was discovered and a structure-function link was established that explains the novel functional capabilities that these enzymes have evolved.

Rights

© 2024, Ricardo Hernandez Arriaza

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