MAT Gain of Activity Mutation in Helicobacter pylori Is Associated with Resistance to MTAN Transition State Analogues

Abstract

Helicobacter pylori is found in the gut lining of more than half of the world’s population, causes gastric ulcers, and contributes to stomach cancers. Menaquinone synthesis in H. pylori relies on the rare futalosine pathway, where H. pylori 5′-methylthioadenosine nucleosidase (MTAN) is proposed to play an essential role. Transition state analogues of MTAN, including BuT-DADMe-ImmA (BTDIA) and MeT-DADMe-ImmA (MTDIA), exhibit bacteriostatic action against numerous diverse clinical isolates of H. pylori with minimum inhibitory concentrations (MIC’s) of <2 ng/mL. Three H. pylori BTDIA-resistant clones were selected under increasing BTDIA pressure. Whole genome sequencing showed no mutations in MTAN. Instead, resistant clones had mutations in metK, methionine adenosyltransferase (MAT), feoA, a regulator of the iron transport system, and flhF, a flagellar synthesis regulator. The mutation in metK causes expression of a MAT with increased catalytic activity, leading to elevated cellular S-adenosylmethionine. Metabolite analysis and the mutations associated with resistance suggest multiple inputs associated with BTDIA resistance. Human gut microbiome exposed to MTDIA revealed no growth inhibition under aerobic or anaerobic conditions. Transition state analogues of H. pylori MTAN have potential as agents for treating H. pylori infection without disruption of the human gut microbiome or inducing resistance in the MTAN target.

The Role of Methionine Restriction in Gastric Cancer: A Summary of Mechanisms and a Discussion on Tumor Heterogeneity

“…On the other hand, the overexpression of Metase significantly promotes apoptosis and autophagy, thereby inhibiting gastric cancer [40,45,46]. Additionally, Met can exert an impact on the development of gastric cancer by influencing the survival of Helicobacter pylori [47][48][49][50]. It has been shown that Met enhances the efficacy of the chemotherapeutic drugs 5-fluorouracil and Cisplatin [47,[51][52][53].…”

Decreased Transition-State Analogue Affinity in Isotopically Heavy MTAN with Increased Catalysis

“…17−19 In bacterial species where these pathways are essential, the DADMe-Immucillin-A inhibitors act as powerful antibiotics. 17,18,20 The transition-state analogue HTDIA was designed to mimic the transition state of MTANs and is a picomolar inhibitor of HpMTAN (Figure 1). Transition-state analogues often exhibit slow-onset, tight-binding inhibition that occurs in two distinct kinetic phases to parallel the interaction of normal reactants with the enzyme.…”

“…Methylthioadenosine nucleosidases (MTANs) are bacterial enzymes that hydrolyze the N -ribosidic bond of methylthioadenosine, S -adenosylhomocysteine, 6-deoxy-6-aminofutolasine, and 5′-deoxyadenosine to form adenine and the modified ribosyl groups. These reactions are important in methylation pathways, polyamine synthesis, quorum sensing, menaquinone synthesis, and in purine, methionine, and S -adenosylmethionine salvage. − Transition-state analogues from the DADMe-Immucillin-A family have been designed to mimic the structure of MTAN transition states and have picomolar affinities for bacterial MTANs. − In bacterial species where these pathways are essential, the DADMe-Immucillin-A inhibitors act as powerful antibiotics. ,, …”