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Structure of a small‐molecule inhibitor complexed with GlmU from Haemophilus influenzae reveals an allosteric binding site
Author(s) -
Mochalkin Igor,
Lightle Sandra,
Narasimhan Lakshmi,
Bornemeier Dirk,
Melnick Michael,
VanderRoest Steven,
McDowell Laura
Publication year - 2008
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1110/ps.073271408
Subject(s) - allosteric regulation , haemophilus influenzae , chemistry , small molecule , binding site , biochemistry , enzyme , antibiotics
N ‐Acetylglucosamine‐1‐phosphate uridyltransferase (GlmU) is an essential enzyme in aminosugars metabolism and an attractive target for antibiotic drug discovery. GlmU catalyzes the formation of uridine‐diphospho‐ N ‐acetylglucosamine (UDP‐GlcNAc), an important precursor in the peptidoglycan and lipopolisaccharide biosynthesis in both Gram‐negative and Gram‐positive bacteria. Here we disclose a 1.9 Å resolution crystal structure of a synthetic small‐molecule inhibitor of GlmU from Haemophilus influenzae ( hi GlmU). The compound was identified through a high‐throughput screening (HTS) configured to detect inhibitors that target the uridyltransferase active site of hi GlmU. The original HTS hit exhibited a modest micromolar potency (IC 50 ∼ 18 μM in a racemic mixture) against hi GlmU and no activity against Staphylococcus aureus GlmU ( sa GlmU). The determined crystal structure indicated that the inhibitor occupies an allosteric site adjacent to the GlcNAc‐1‐P substrate‐binding region. Analysis of the mechanistic model of the uridyltransferase reaction suggests that the binding of this allosteric inhibitor prevents structural rearrangements that are required for the enzymatic reaction, thus providing a basis for structure‐guided design of a new class of mechanism‐based inhibitors of GlmU.