Acinetobacter baumannii Can Survive with an Outer Membrane Lacking Lipooligosaccharide Due to Structural Support from Elongasome Peptidoglycan Synthesis
Brent W. Simpson, Marta Nieckarz, Victor Pinedo, Amanda B. McLean, Felipe Cava, M. Stephen Trent
Abstract
Gram-negative bacteria have a multilayered cell envelope with a layer of cross-linked polymers (peptidoglycan) sandwiched between two membranes. Peptidoglycan was long thought to exclusively provide rigidity to the cell providing mechanical strength. Recently, the most outer membrane of the cell was also proposed to contribute to rigidity due to properties of a unique molecule called lipopolysaccharide (LPS). LPS is located on the cell surface in the outer membrane and is typically required for growth. By using Acinetobacter baumannii, a Gram-negative bacterium that can grow without LPS, we found that key features of the peptidoglycan structure also become essential. This finding supports that both the outer membrane and peptidoglycan contribute to cell rigidity.