Discovery of Allosteric and Selective Inhibitors of Inorganic Pyrophosphatase from Mycobacterium tuberculosis.
Inorganic pyrophosphatase (PPiase) is an essential enzyme that hydrolyzes inorganic pyrophosphate (PPi), driving numerous metabolic processes. We report a discovery of an allosteric inhibitor (2,4-bis(aziridin-1-yl)-6-(1-phenylpyrrol-2-yl)-s-triazine) of bacterial PPiases. Analogues of this lead compound were synthesized to target specifically Mycobacterium tuberculosis (Mtb) PPiase (MtPPiase). The best analogue (compound 16) with a Kiof 11 μM for MtPPiase is a species-specific inhibitor. Crystal structures of MtPPiase in complex with the lead compound and one of its analogues (compound 6) demonstrate that the inhibitors bind in a nonconserved interface between monomers of the hexameric MtPPiase in a yet unprecedented pairwise manner, while the remote conserved active site of the enzyme is occupied by a bound PPisubstrate. Consistent with the structural studies, the kinetic analysis of the most potent inhibitor has indicated that it functions uncompetitively, by binding to the enzyme-substrate complex. The inhibitors appear to allosterically lock the active site in a closed state causing its dysfunctionalization and blocking the hydrolysis. These inhibitors are the first examples of allosteric, species-selective inhibitors of PPiases, serving as a proof-of-principle that PPiases can be selectively targeted.
Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky , 789 South Limestone Street, Lexington, Kentucky 40536-0596, United States.
Allan H
AH
Pang
Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky , 789 South Limestone Street, Lexington, Kentucky 40536-0596, United States.
Atefeh
A
Garzan
Center for Chemical Genomics, High-Throughput Screening Laboratory, Life Sciences Institute, University of Michigan , Ann Arbor, Michigan 48109, United States.
Martha J
MJ
Larsen
Center for Chemical Genomics, High-Throughput Screening Laboratory, Life Sciences Institute, University of Michigan , Ann Arbor, Michigan 48109, United States.
Thomas J
TJ
McQuade
Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky , 789 South Limestone Street, Lexington, Kentucky 40536-0596, United States.
Sylvie
S
Garneau-Tsodikova
Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky , 789 South Limestone Street, Lexington, Kentucky 40536-0596, United States.
Oleg V
OV
Tsodikov
D000494:Allosteric Regulation; D018360:Crystallography, X-Ray; D055808:Drug Discovery; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D043564:Inorganic Pyrophosphatase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D015394:Molecular Structure; D009169:Mycobacterium tuberculosis / Q000201:enzymology*
D004791:Enzyme Inhibitors; D043564:Inorganic Pyrophosphatase