Aminolipids elicit functional trade-offs between competitiveness and bacteriophage attachment in Ruegeria pomeroyi

Area of Science:

• Microbiology
• Marine Biology
• Biochemistry

Background:

• Lipids are vital for cell integrity and homeostasis.
• Marine roseobacter clade (MRC) and SAR11 bacteria uniquely produce amino acid-containing lipids alongside glycerophospholipids.
• Ornithine aminolipid (OL) and glutamine aminolipid (QL) are synthesized by O-acetyltransferase OlsA.

Purpose of the Study:

• To investigate the role of OL and QL in the Gram-negative bacterium Ruegeria pomeroyi DSS-3.
• To understand the consequences of aminolipid deficiency on membrane properties, nutrient transport, and bacterial fitness.
• To explore the implications for marine bacterial ecophysiology and phage interactions.

Main Methods:

• Analysis of an olsA mutant in Ruegeria pomeroyi DSS-3.
• Characterization of membrane composition and proteome.
• Measurement of nutrient import (choline, dimethylsulfoniopropionate).
• Co-culture experiments to assess bacterial competitiveness.
• Assays for bacteriophage attachment susceptibility.

Main Results:

• Loss of OL and QL in the olsA mutant was compensated by increased glycerophospholipids.
• Aminolipid deficiency altered membrane proteome, reducing permeability and downregulating nutrient transporters.
• Nutrient import was significantly impaired in the olsA mutant.
• The olsA mutant exhibited reduced competitiveness in co-culture but decreased susceptibility to phage attachment.
• A trade-off between growth and phage avoidance was observed.

Conclusions:

• Aminolipids are critical for the ecophysiology of marine bacteria like Ruegeria pomeroyi.
• The absence of these lipids affects membrane function, nutrient acquisition, and inter-bacterial competition.
• Aminolipid synthesis influences susceptibility to bacteriophages, highlighting a survival strategy trade-off.