Proteome-wide cellular protein concentrations of the human pathogen Leptospira interrogans

Absolute protein quantification via the measurement of protein copy numbers has the potential to provide important information about biological processes, but apart from the special case of brewers yeast, this has not proved possible using standard proteomics procedures. Now, with the leptospirosis pathogen Leptospira interrogans as the first target, a new mass spectrometry-based strategy that should be generally applicable to many other biological systems has been used to determine absolute protein abundance for a significant fraction of a proteome. The results show how L. interrogans adapts to changing environments by adjusting proteome homeostasis while the total protein copy numbers remain constant.