Liquid chromatography-mass spectrometry-based proteomics of Nitrosomonas.

During the last century, the research on aerobic ammonium-oxidizing bacteria (AOB) lead to many exciting physiological and biochemical discoveries. Nevertheless the molecular biology of AOB is not well understood. The availability of the genome sequences of several Nitrosomonas species opened up new possiblities to use state of the art transcriptomic and proteomic tools to study AOB. With the currect technology, thousands of proteins can be analyzed in several hours of measurement and translated proteins can be detected at femtomole and attomole concentrations. Moreover, it is possible to use mass spectrometry-based proteomics approach to analyze the expression, subcellular localization, posttranslational modifications, and interactions of translated proteins. In this chapter, we describe our LC-MS/MS methodology and quality control strategy to study the protein complement of Nitrosomonas eutropha C91.