The Pseudomonas aeruginosa substrate-binding protein Ttg2D functions as a general glycerophospholipid transporter across the periplasm

Abstract In Pseudomonas aeruginosa , Ttg2D is the soluble periplasmic phospholipid-binding component of an ABC transport system thought to be involved in maintaining asymmetry outer membrane. Here we use crystallographic structure at 2.5 Å resolution reveal that this protein can accommodate four acyl chains. Analysis available structures orthologs shows they conform a new substrate-binding-protein structural cluster. Native and denaturing mass spectrometry experiments confirm Ttg2D, produced both heterologously homologously isolated from periplasm, carry two diacyl glycerophospholipids as well one cardiolipin. Binding notably promiscuous, allowing various molecular species. vitro binding assays coupled native show cardiolipin spontaneous. Gene knockout P. multidrug-resistant strains Ttg2 low-level intrinsic resistance against certain antibiotics lipid-mediated pathway permeate through membranes.