PNNL

Abstract

In this study, the intact periplasmic proteome of Novosphingobium aromaticivorans was analyzed. We identified 55 proteins in the periplasm, and characterized their post translational modifications. Proteins were first categorized based on their N-terminal processing: 17 proteins were identified with removal of signal peptides containing the canonical A-X-A motif, 8 proteins were identified with removal of signal peptides containing non A-X-A motif, 24 proteins were identified with N-terminal methione excision (NME), and 4 proteins were identified with other N-terminal processing (e.g. complex proteolysis). Only 2 proteins were identified with no N-terminal modifications. Other observed protein post-translational modifications included acetylation, glutathiolynation, pyroglutamate modification, disulfide bond formation, etc. In summary, we analyzed the intact periplasmic proteins of N. aromaticivorans in a high throughput fashion, and provided a catalogue of information on post-translational modifications observed in this dynamic subcellular fraction. This study provides the first experimental evidence for the expression and periplasmic localization of hypothetical and uncharacterized proteins, and the first unrestrictive, large-scale data on post-translational modifications in the bacterial periplasm.