OMICS assisted N-terminal proteoform and protein expression profiling upon methionine aminopeptidase 1 (MetAP1) deletion

Excision of the N-terminal initiator methionine (iMet) residue from nascent peptide chains is an essential and omnipresent protein modification carried out by methionine aminopeptidases (MetAPs) that accounts for a major source of N-terminal proteoform diversity. While MetAP2 is known to be implicated in processes such as angiogenesis and proliferation in mammals, the physiological role of MetAP1 is much less clear. In this report we studied the omics-wide effects of human MetAP1 deletion and general MetAP inhibition. The levels of iMet retention are inversely correlated with cellular proliferation rates. Further, despite the increased MetAP2 expression observed upon MetAP1 deletion and as inferred from the iMet retention profiles observed, MetAP2 was unable to restore processing of MS-, MP- and MA- N-termini, indicating the higher activity of MetAP1 over these N-termini. Proteome and transcriptome expression profiling point to differential expression of proteins implicated in lipid metabolism, cytoskeleton organization, cell proliferation and protein synthesis upon perturbation of MetAP activity. Overall design: RNA sequencing of wild type (parental) and METAP1 knockout HAP1 cells.