Symposium Presentation Australian Society for Microbiology Annual Scientific Meeting 2024

The patatin-like protein PlpD forms novel structurally dynamic homodimers in the Pseudomonas aeruginosa outer membrane. (104155)

Sarah E Hanson 1 , Tyrone Dowdy 2 , Mioara Larion 2 , Matthew T Doyle 3 , Harris D Bernstein 1
  1. Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases / National Institutes of Health, Bethesda, MD, USA
  2. Neuro-Oncology Branch, National Cancer Institute / National Institutes of Health, Bethesda, MD, USA
  3. Sydney Infectious Diseases Institute and School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Darlington, NSW

Members of the Omp85 superfamily of outer membrane proteins (OMPs) found in Gram-negative bacteria, mitochondria and chloroplasts are characterized by a distinctive 16-stranded β-barrel transmembrane domain and at least one periplasmic POTRA domain. All previously studied Omp85 proteins promote critical OMP assembly and/or protein translocation reactions. Pseudomonas aeruginosa PlpD is the prototype of an Omp85 protein family that contains an N-terminal patatin-like (PL) domain that is thought to be translocated across the OM by a C-terminal β-barrel domain. Challenging the current dogma, we found that the PlpD PL-domain resides exclusively in the periplasm and, unlike previously studied Omp85 proteins, PlpD forms a homodimer. Remarkably, the PL-domain contains a segment that exhibits unprecedented dynamicity by undergoing transient strand-swapping with the neighboring β-barrel domain. Our results show that the Omp85 superfamily is more structurally diverse than currently believed and suggest that the Omp85 scaffold was utilized during evolution to generate novel functions.