Following phospholipid transfer through the OmpF 3 –MlaA–MlaC lipid shuttle with native mass spectrometry

• DOI: 10.1073/pnas.2420041122
• Publication Date: 2025-04-01T16:14:43Z
• Authors: Carla Kirschbaum; Jack L. Bennett; Qiaoyu Tian; Navoneel Sen; Iain P. S. Smith; Di Wu; Justin L. P. Benesch; Syma Khalid; Georgia Isom; Carol V. Robinson

The maintenance of lipid asymmetry (Mla) system in gram-negative bacteria transfers phospholipids between the outer and inner membrane to maintain asymmetry. Misplaced are extracted from leaflet by MlaA, transferred periplasmic transporter MlaC, shuttled membrane. We set out investigate transfer MlaA MlaC using native mass spectrometry, with aim determining preferences whether preselected lipids for MlaC. First, we characterized that copurified overexpressed phosphatidylglycerol (PG), phosphatidylethanolamine (PE), following delipidation noted a headgroup-independent enrichment cyclopropane lipids. Under expression conditions, found PG is three-fold enriched on compared its abundance Next, isolated OmpF 3 –MlaA complexes demonstrated their ability enhance loading delipidated bacterial nonbacterial phospholipids. then captured intact ternary shuttle (OmpF –MlaA–MlaC) dissociates this transient complex, releasing lipid-bound Together our results point high population endogenous which likely arises disassembly cell viability.