Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001, C.P. 62210, Cuernavaca, Morelos, Mexico.
Centro de Investigación Sobre Enfermedades Infecciosas, Instituto Nacional de Salud Pública, Cuernavaca, Morelos, Mexico.
Biochem Biophys Res Commun. 2020 Feb 5;522(2):545-551. doi: 10.1016/j.bbrc.2019.11.138. Epub 2019 Nov 25.
β-lactamases are the main molecules responsible for giving bacterial resistance against β-lactam antibiotics. The study of β-lactamases has allowed the development of antibiotics capable of inhibiting these enzymes. In this context, extended spectrum β-lactamase (ESBL) TLA-1 has spread in Escherichia coli and Enterobacter cloacae clinical isolates during the last 30 years in Mexico. In this research, the 3D structures of ESBL TLA-1 and TLA-1 S70G mutant, both ligand-free and in complex with clavulanic acid were determined by X-ray crystallography. Four clavulanic acid molecules were found in the structure of TLA-1, two of those were intermediaries of the acylation process and were localized covalently bound to two different amino acid residues, Ser70 and Ser237. The coordinates of TLA-1 in complex with clavulanic acid shows the existence of a second acylation site, additional to Ser70, which might be extendable to several members of the subclass A β-lactamases family. This is the first time that two serines involved in binding clavulanic acid has been reported and described to an atomic level.
β-内酰胺酶是导致细菌对β-内酰胺类抗生素产生耐药性的主要分子。对β-内酰胺酶的研究促使了能够抑制这些酶的抗生素的发展。在这种情况下，扩展谱β-内酰胺酶（ESBL）TLA-1 在过去 30 年中在墨西哥的大肠杆菌和阴沟肠杆菌临床分离株中传播。在这项研究中，通过 X 射线晶体学确定了无配体和与克拉维酸复合的 ESBL TLA-1 和 TLA-1 S70G 突变体的 3D 结构。在 TLA-1 的结构中发现了四个克拉维酸分子，其中两个是酰化过程的中间体，共价结合到两个不同的氨基酸残基 Ser70 和 Ser237 上。与克拉维酸结合的 TLA-1 的坐标显示存在第二个酰化位点，除了 Ser70 之外，该位点可能可扩展到 A 类β-内酰胺酶家族的几个成员。这是首次在原子水平上报道和描述了两个参与结合克拉维酸的丝氨酸。
