Novel highly sensitive, specific, and straightforward strategy for comprehensive N-terminal proteomics reveals unknown substrates of the mitochondrial peptidase icp55

21.08.2013

Venne AS, Vögtle FN, Meisinger C, Sickmann A, Zahedi RP

J Proteome Res. 2013 Sep 6;12(9):3823-30

J Proteome Res.       online article

We present a novel straightforward method for enrichment of N-terminal peptides, utilizing charge-based fractional diagonal chromatography (ChaFRADIC).Icp55 is an intermediate cleaving peptidase, which, following mitochondrial processing peptidase (MPP)-dependent cleavage of signal sequences, removes a single amino acid from a specific set of proteins according to the N-end rule. Using ChaFRADIC we identified 36 icp55 substrates, 14 of which were previously unknown, expanding the set of known icp55 substrates to a total of 52 proteins. Interestingly, a novel substrate, Isa2, is likely processed by Icp55 in two consecutive steps and thus might represent the first example of a triple processing event in a mitochondrial precursor protein.