In Vivo Cross-Linking MS Reveals Conservation in OmpA Linkage to Different Classes of β‑Lactamase Enzymes

Molecular interactions between two different classes of β-lactamase enzymes and outer membrane protein A (OmpA) were studied by in vivo chemical cross-linking of a multi-drug-resistant strain of Acinetobacter baumannii AB5075. Class A β-lactamase blaGES-11 and Class D β-lactamase Oxa23, responsible for hydrolysis of different types of β-lactam antibiotics, were found to be cross-linked to similar lysine sites of the periplasmic domain of outer membrane protein OmpA, despite low sequence homology between the two enzymes. The findings from in vivo XL-MS suggest that the interacting surfaces between both β-lactamase enzymes and OmpA are conserved during molecular evolution, and the OmpA C-terminus domain serves an important function of anchoring different types of β-lactamase enzymes in the periplasmic space.

本研究以多重耐药鲍曼不动杆菌AB5075菌株为实验材料，通过体内化学交联技术，解析了两类不同β-内酰胺酶（β-lactamase）与外膜蛋白A（outer membrane protein A, OmpA）之间的分子相互作用。其中负责催化水解不同类型β-内酰胺类抗生素的A类β-内酰胺酶blaGES-11与D类β-内酰胺酶Oxa23，尽管二者序列同源性较低，但均被证实可与外膜蛋白OmpA周质结构域的相似赖氨酸位点发生交联。体内交联质谱（in vivo XL-MS）分析结果表明，两种β-内酰胺酶与OmpA的相互作用界面在分子进化过程中具有保守性；OmpA的C端结构域可在周质空间中锚定不同类型的β-内酰胺酶，发挥重要功能。