Tracking nitrogen allocation to proteome biosynthesis in a marine microbial community

Area of Science:

• Microbial Ecology
• Biogeochemistry
• Proteomics

Background:

• Nitrogen availability is a key factor limiting microbial growth in diverse environments.
• Understanding how microbial communities compete for and allocate nitrogen is crucial but poorly understood.

Purpose of the Study:

• To develop a broadly applicable method for tracking nitrogen substrate incorporation into microbial proteomes.
• To quantify protein turnover and nitrogen allocation to specific cellular functions within individual microbial taxa.

Main Methods:

• Utilized 15N-labelled nitrogen substrates to track biosynthetic incorporation into microbial community proteomes.
• Applied the method to oligotrophic ocean surface water samples.
• Quantified protein turnover and nitrogen allocation across different taxa and cellular functions.

Main Results:

• Identified taxa-specific nitrogen substrate preferences in marine microbial communities.
• Revealed a distinct subset of protein functions actively undergoing biosynthesis.
• Showcased Prochlorococcus as a highly effective competitor for ammonium and urea, with dynamic nitrogen allocation.
• Demonstrated that infrastructure and protein-turnover functions represent significant nitrogen demands.

Conclusions:

• The developed 15N-tracking proteomics approach effectively elucidates the proteomic basis of nitrogen limitation.
• Nutrient stress differentially impacts microbial metabolism, influencing resource allocation in co-existing species.
• Provides new insights into microbial competition and nitrogen cycling in marine ecosystems.