Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, L'Aquila, Italy.
Department of Experimental and Clinical Medicine, University of Florencegrid.8404.8, Florence, Italy.
Antimicrob Agents Chemother. 2022 Sep 20;66(9):e0059522. doi: 10.1128/aac.00595-22. Epub 2022 Aug 30.
The MOX lineage of β-lactamases includes a group of molecular class C enzymes (AmpCs) encoded by genes mobilized from the chromosomes of spp. to plasmids. MOX-9, previously identified as a plasmid-encoded enzyme from a Citrobacter freundii isolate, belongs to a novel sublineage of MOX enzymes, derived from the resident Aeromonas media AmpC. The gene was found to be carried on a transposon, named Tn, likely responsible for its mobilization to plasmidic context. MOX-9 was overexpressed in Escherichia coli, purified, and subjected to biochemical characterization. Kinetic analysis showed a relatively narrow-spectrum profile with strong preference for cephalosporin substrates, with some differences compared with MOX-1 and MOX-2. MOX-9 was not inhibited by clavulanate and sulbactam, while both tazobactam and avibactam acted as inhibitors in the micromolar range.
β-内酰胺酶的 MOX 谱系包括一组分子分类 C 酶（AmpC），这些酶由 spp. 的染色体上的基因转移到质粒上编码。MOX-9 先前被鉴定为源自弗氏柠檬酸杆菌分离株的质粒编码酶，属于 MOX 酶的一个新亚谱系，源自常驻气单胞菌属媒介物 AmpC。 基因被发现携带在转座子上，命名为 Tn，可能负责其向质粒环境的转移。MOX-9 在大肠杆菌中过表达、纯化并进行了生化特性分析。动力学分析显示出相对狭窄的谱型，对头孢菌素底物具有强烈的偏好，与 MOX-1 和 MOX-2 相比存在一些差异。MOX-9 不受克拉维酸和舒巴坦的抑制，而他唑巴坦和阿维巴坦均以微摩尔范围的抑制剂发挥作用。
