Dataset: Trichodesmium proteomes and Hi CO2 adaptation
Deployment: lab_Webb_Hutchins_Fu

The following are excerpts from Walworth et al. 2016a. Please refer to this reference for more details of the methodology used to generate these data.

"Protein spectral counts are generated by extracting proteins from cells, digesting into smaller peptides, separating them on HPLC (high-performance liquid chromatography), and measuring peptide masses on a mass spectrometer to ascertain mass-to-charge ratio. Peptide fragment ratios are then compared to a reference genome and spectral counts per protein are enumerated."

"Nitrogen fixation by cyanobacteria supplies critical bioavailable nitrogen to marine ecosystems worldwide; however, field and lab data have demonstrated it to be limited by iron, phosphorus and/or CO2. To address unknown future interactions among these factors, we grew the nitrogen-fixing cyanobacterium Trichodesmium for 1 year under Fe/P co-limitation following 7 years of both low and high CO2 selection. Fe/P co-limited cell lines demonstrated a complex cellular response including increased growth rates, broad proteome restructuring and cell size reductions relative to steady-state growth limited by either Fe or P alone. Fe/P co-limitation increased abundance of a protein containing a conserved domain previously implicated in cell size regulation, suggesting a similar role in Trichodesmium. Increased CO2 further induced nutrient-limited proteome shifts in widespread core metabolisms. Our results thus suggest that N2-fixing microbes may be significantly impacted by interactions between elevated CO2 and nutrient limitation, with broad implications for global biogeochemical cycles in the future ocean."

"Spectral counts compare a specific protein’s abundance between treatments, rather than against other proteins, because the sensitivity of spectral counts can vary between proteins depending on the number of tryptic peptides within the sequence and their chemical characteristics."