Catalytic Mechanism of Mycobacterium tuberculosis Methionine Sulfoxide Reductase A

MYCOBACTERIUM TUBERCULOSIS

TUBERCULOSIS

MICOBACTERIAS

MECANISMO CATALITICO

QM/MM

ENERGIA LIBRE

UMBRELLA SAMPLING

METIONINA

SULFOXIDO

BIBLIOGRAFIA NACIONAL QUIMICA

2024

The oxidation of Met to methionine sulfoxide (MetSO) by oxidants such as hydrogen peroxide, hypochlorite, or peroxynitrite has profound effects on protein function. This modification can be reversed by methionine sulfoxide reductases (msr). In the context of pathogen infection, the reduction of oxidized proteins gains significance due to microbial oxidative damage generated by the immune system. For example, Mycobacterium tuberculosis (Mt) utilizes msrs (MtmsrA and MtmsrB) as part of the repair response to the host-induced oxidative stress. The absence of these enzymes makes Mycobacteria prone to increased susceptibility to cell death, pointing them out as potential therapeutic targets. This study provides a detailed characterization of the catalytic mechanism of MtmsrA using a comprehensive approach, including experimental techniques and theoretical methodologies. Confirming a ping-pong type enzymatic mechanism, we elucidate the catalytic parameters for sulfoxide and thioredoxin substrates (kcat/KM = 2656 ± 525 M−1 s−1 and 1.7 ± 0.8 × 106 M−1 s−1, respectively). Notably, the entropic nature of the activation process thermodynamics, representing ∼85% of the activation free energy at room temperature, is underscored. Furthermore, the current study questions the plausibility of a sulfurane intermediate, which may be a transition-state-like structure, suggesting the involvement of a conserved histidine residue as an acid−base catalyst in the MetSO reduction mechanism. This mechanistic insight not only advances our understanding of Mt antioxidant enzymes but also holds implications for future drug discovery and biotechnological applications.

Sastre, Santiago

Manta, Bruno.

Semelak, Jonathan A.

Estrin, Dario

Trujillo Garré, Madia

Radi, Rafael

Zei, Ari

ACS Publications

Biochemistry, v.63, 2024. -- pp.533−544

2024

PDF

12 p.

Inglés

Artículo

10.1021/acs.biochem.3c00504

PDF