PNNL

Abstract

Proteomes from aerobic and photosynthetic grown Rhodobacter sphaeroides 2.4.1 cell cultures were characterized using liquid chromatography-mass spectrometry in conjunction with an accurate mass and elution time (AMT) tag approach. Roughly 8000 high quality peptides were detected that represented 1,445 gene products and 34% of the predicted proteins. The identified proteins corresponded primarily to open reading frames (ORFs) contained within the two chromosomal elements of this bacterium, but a significant number were also observed from ORFs associated with 5 naturally occurring plasmids. Data mining of peptides revealed a number of proteins uniquely detected within the photosynthetic cell culture. Proteins observed in both aerobic respiratory and photosynthetic grown cultures were analyzed semi-quantitatively by comparing their estimated abundances to provide insights into bioenergetic models for aerobic respiration and photosynthesis. Additional emphasis was placed on gene products annotated as hypothetical to gain information as to their potential roles within these two growth conditions. Where possible, transcriptome data for R. sphaeroides obtained under the same culture conditions were compared with these results. This comparative study demonstrated the applicability of the AMT tag approach for high-throughput proteomic analyses of pathways associated with the photosynthetic lifestyle.