Monteiro Ricardo, Cereija Tatiana B, Pombinho Rita, Voskuilen Thijs, Codée Jeroen D C, Sousa Sandra, Morais-Cabral João H, Cabanes Didier
i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.
IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal.
Nat Commun. 2025 Jan 2;16(1):24. doi: 10.1038/s41467-024-55360-1.
Wall teichoic acids (WTAs) from the major Gram-positive foodborne pathogen Listeria monocytogenes are peptidoglycan-associated glycopolymers decorated by monosaccharides that, while not essential for bacterial growth, are required for bacterial virulence and resistance to antimicrobials. Here we report the structure and function of a bacterial WTAs rhamnosyltransferase, RmlT, strictly required for L. monocytogenes WTAs rhamnosylation. In particular, we demonstrated that RmlT transfers rhamnose from dTDP-L-rhamnose to naked WTAs, and that specificity towards TDP-rhamnose is not determined by its binding affinity. Structures of RmlT with and without its substrates showed that this enzyme is a dimer, revealed the residues responsible for interaction with the substrates and that the catalytic residue pre-orients the acceptor substrate towards the nucleophilic attack to the sugar. Additionally, the structures provided indications for two potential interaction pathways for the long WTAs on the surface of RmlT. Finally, we confirmed that WTAs glycosyltransferases are promising targets for next-generation strategies against Gram-positive pathogens by showing that inactivation of the RmlT catalytic activity results in a decreased infection in vivo.
来自主要的革兰氏阳性食源性病原体单核细胞增生李斯特菌的壁磷壁酸（WTA）是与肽聚糖相关的糖聚合物，由单糖修饰，虽然对细菌生长不是必需的，但对细菌毒力和抗微生物耐药性是必需的。在此，我们报道了一种细菌WTA鼠李糖基转移酶RmlT的结构和功能，它是单核细胞增生李斯特菌WTA鼠李糖基化严格必需的。特别是，我们证明RmlT将鼠李糖从dTDP-L-鼠李糖转移到裸露的WTA上，并且对TDP-鼠李糖的特异性不是由其结合亲和力决定的。有底物和无底物时RmlT的结构表明该酶是二聚体，揭示了与底物相互作用的残基，并且催化残基使受体底物预先定向以接受对糖的亲核攻击。此外，这些结构为RmlT表面上长WTA的两条潜在相互作用途径提供了线索。最后，我们通过表明RmlT催化活性的失活导致体内感染减少，证实了WTA糖基转移酶是对抗革兰氏阳性病原体的下一代策略的有前景的靶点。
