Structure of the Trehalose-6-phosphate Phosphatase from Brugia malayi Reveals Key Design Principles for Anthelmintic Drugs |
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| Authors: | Jeremiah D Farelli Brendan D Galvin Zhiru Li Chunliang Liu Miyuki Aono Megan Garland Olivia E Hallett Thomas B Causey Alana Ali-Reynolds Daniel J Saltzberg Clotilde K S Carlow Debra Dunaway-Mariano Karen N Allen |
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| Institution: | 1. Department of Chemistry, Boston University, Boston, Massachusetts, United States of America.; 2. New England Biolabs, Division of Parasitology, Ipswich, Massachusetts, United States of America.; 3. Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico, United States of America.; Rush University Medical Center, United States of America, |
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| Abstract: | Parasitic nematodes are responsible for devastating illnesses that plague many of the world''s poorest populations indigenous to the tropical areas of developing nations. Among these diseases is lymphatic filariasis, a major cause of permanent and long-term disability. Proteins essential to nematodes that do not have mammalian counterparts represent targets for therapeutic inhibitor discovery. One promising target is trehalose-6-phosphate phosphatase (T6PP) from Brugia malayi. In the model nematode Caenorhabditis elegans, T6PP is essential for survival due to the toxic effect(s) of the accumulation of trehalose 6-phosphate. T6PP has also been shown to be essential in Mycobacterium tuberculosis. We determined the X-ray crystal structure of T6PP from B. malayi. The protein structure revealed a stabilizing N-terminal MIT-like domain and a catalytic C-terminal C2B-type HAD phosphatase fold. Structure-guided mutagenesis, combined with kinetic analyses using a designed competitive inhibitor, trehalose 6-sulfate, identified five residues important for binding and catalysis. This structure-function analysis along with computational mapping provided the basis for the proposed model of the T6PP-trehalose 6-phosphate complex. The model indicates a substrate-binding mode wherein shape complementarity and van der Waals interactions drive recognition. The mode of binding is in sharp contrast to the homolog sucrose-6-phosphate phosphatase where extensive hydrogen-bond interactions are made to the substrate. Together these results suggest that high-affinity inhibitors will be bi-dentate, taking advantage of substrate-like binding to the phosphoryl-binding pocket while simultaneously utilizing non-native binding to the trehalose pocket. The conservation of the key residues that enforce the shape of the substrate pocket in T6PP enzymes suggest that development of broad-range anthelmintic and antibacterial therapeutics employing this platform may be possible. |
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