UC San Diego

This thesis will explore N-terminal methionine excision (NME), a co-translational process that occurs on virtually all proteins in all organimsms from bacteria to eukaryotes. NME is an essential process for the funtioning of proteins, with the enzymes responsible for carrying out NME belonging to the minimal bacterial cell (HPG⁺99). This excision is almost exclusively determined by the second amino acid of the nascient protein. The set of seven amino acids that prompt cleavage also correspond to the seven stabilizing amino acids that Arfin and Bradshaw [AB88] connected to protein degradation. Comparative proteogenomics approaches are employed to perform an analysis of NME based on sequence as well as other available data. The ties of NME to protein degradation are questioned, with the results of experiments suggesting that only two of the seven amino acids that prompt cleavage are important and required for post-translational modifications, specifically N-acetylation