A surface-exposed cardiolipin synthase provides an unexpected paradigm for maintaining the Gram-negative outer membrane.

ABSTRACT: Gram-negative bacteria have long been thought to confine primary glycerophospholipid synthesis to the inner membrane (IM). Here, we challenge this paradigm by identifying ClsO, an outer membrane (OM) lipoprotein from Acinetobacter baumannii that functions as a cardiolipin synthase. In contrast to canonical cardiolipin synthases, which are restricted to the IM, ClsO is surface-exposed and deposits cardiolipin into the outer leaflet of the OM, colocalizing with Acinetobacter lipooligosaccharide. Loss of ClsO sensitizes cells to membrane disrupting agents, such as bile salts, and key antibiotics, implicating ClsO in OM barrier integrity. ClsO activity increases when mislocalized glycerophospholipids accumulate at the cell surface, such as in cells lacking Mla (maintenance of lip

SUBMITTER: Herrera CM 

PROVIDER: S-EPMC12846801 | biostudies-literature | 2026 Jan

REPOSITORIES: biostudies-literature