Stable Analogues of OSB‐AMP: Potent Inhibitors of MenE, the o‐Succinylbenzoate‐CoA Synthetase from Bacterial Menaquinone Biosynthesis

Abstract

MenE, the o-succinylbenzoate (OSB)-CoA synthetase from bacterial menaquinone biosynthesis, is a promising new antibacterial target. Sulfonyladenosine analogues of the cognate reaction intermediate, OSB-AMP, have been developed as inhibitors of the MenE enzymes from Mycobacterium tuberculosis (mtMenE), Staphylococcus aureus (saMenE) and Escherichia coli (ecMenE). Both a free carboxylate and ketone moiety on the OSB side chain are required for potent inhibitory activity. OSB-AMS (4) is a competitive inhibitor of mtMenE with respect to ATP (Ki = 5.4 ± 0.1 nM) and a non-competitive inhibitor with respect to OSB (Ki = 11.2 ± 0.9 nM). These data are consistent with a bi uni uni bi ping-pong kinetic mechanism for these enzymes. In addition, OSB-AMS inhibits saMenE with Kiapp of 22 ± 8 nM and ecMenE with KiOSB=128±5nM. Putative active site residues, Arg-222, which may interact with the OSB aromatic carboxylate, and Ser-302, which may bind the OSB ketone oxygen, have been identified through computational docking of OSB-AMP with the unliganded crystal structure of saMenE. A pH-dependent interconversion of the free keto acid and lactol forms of the inhibitors is also described, along with implications for inhibitor design.

Menaquinone biosynthesis inhibition: a review of advancements toward a new antibiotic mechanism

“…The h enzyme in the bacterial synthesis of 1, MenE catalyses the addition of S-CoA to OSB via an OSB-AMP intermediate. 15,23,25,[28][29][30] Aer initial location and characterization of the MenE gene by Sharma, 29 varying approaches have been undertaken to attempt to inhibit this enzyme. The reaction mechanisms of MenE have been proposed by Tian et al 15 where they describe the reaction as a Bi Uni Uni Bi ping-pong mechanism in the presence of ATP, via an acyl-AMP intermediate.…”

Structural Basis for the ATP-dependent Configuration of Adenylation Active Site in Bacillus subtilis o-Succinylbenzoyl-CoA Synthetase

“…The fact that this strictly conserved lysine interacts with the ␤-phosphate of ATP in DltA and ACSM2A shows that its side chain is highly dynamic and flexible. The crucial catalytic role of the invariant A10 lysine residue is strongly supported by the complete activity loss in the adenylation half-reaction without affecting the thioesterification half-reaction in several ANL enzymes when it is mutated (8,13,20,66,67). It is also supported by the hydrogen bonding interaction of this residue with the ␣-phosphoryl group in complexes of the adenylate-AMP intermediate or analogues with several ANL enzymes, including BsMenE (17,18,61,68) and the use of acetylation of this residue as a regulation control of acetyl-CoA synthetase in mammals (46).…”

Identification of a Hotdog Fold Thioesterase Involved in the Biosynthesis of Menaquinone in Escherichia coli

“…It is synthesized from chorismate either through a pathway involving o-succinylbenzoic acid (OSB) as a precursor (6) or through a newly discovered pathway using futalosine as an intermediate (7,8). Due to its absence in humans and animals, the bacterial menaquinone biosynthesis has been an attractive target for development of novel antibiotics against pathogenic microbes such as Mycobacterium tuberculosis (9)(10)(11).…”