PNNL

Abstract

The global protein analysis of Geobacter sulfurreducens, a model for the Geobacter species that predominate in many Fe(III)-reducing subsurface environments, was characterized with ultra high pressure liquid chromatography and mass spectrometry using accurate mass and time (AMT) tags as well as with more traditional two-dimensional polyacrylamide gel electrophoresis (2-D PAGE). Cells were grown under eight different growth conditions in order to enhance the potential that genes would be expressed. Over 3,187 gene products, representing about 92% of the total predicted gene products in the genome, were detected. The AMT approach was able to identify a much higher number of proteins than could be detected with the 2-D PAGE approach. A high proportion of predicted proteins in most protein role categories were detected with the highest number of proteins identified in the hypothetical protein role category. Furthermore, 91 c-type cytochromes of 111 predicted genes in the G. sulfurreducens genome were identified. Localization studies indicated that computational predictions of cytochrome location were limited. Differences in the abundance of cytochromes and other proteins under different growth conditions provided information for future functional analysis of these proteins. These results demonstrate that a high percentage of the predicted proteins in the G. sulfurreducens genome are produced and that the AMT approach provides a rapid method for comparing differential expression of proteins under different growth conditions in this organism.