Role of basic amino acids in the cleavage of synthetic peptide substrates by mitochondrial processing peptidase.
Our recent experiments using model peptides of rat malate dehydrogenase (MDH) indicated that a proximal arginine and a distal basic amino acid are important for processing by mitochondrial processing peptidase (MPP). [Niidome, T., Kitada, S., Shimokata, K., Ogishima, T., and Ito, A. (1994) J. Biol. Chem. 269, 24719-24722]. To elucidate if the recognition elements apply to other precursor proteins, we analyzed cleavage of model peptides of human ornithine aminotransferase (OAT). Purified peptidase cleaved peptides that corresponded to N-terminal 1-25 and 3-25 at the correct site (Gly17-Val18) at nearly equal rates. Replacement of Arg16 (-2 position) with lysine or alanine reduced the processing efficiency by 95- and 380-fold, respectively. Either deletion from Met1 to Arg10 or replacement of the basic amino acids between them decreased the processing efficiency considerably. A peptide containing Arg7 in addition to Lys4 and Arg10 was more effective than the control peptide. However, a peptide with one and two consecutive basic amino acids in the distal region had a processing efficiency close to the control peptide. These results indicated that processing of OAT was enhanced by an increase in the number of basic amino acids with a suitable distance between them. In other respects, the processing signal of OAT was essentially the same as that of MDH.
Song
M C
MC
Department of Chemistry, Faculty of Science, Kyushu University, Fukuoka.
Shimokata
K
K
Kitada
S
S
Ogishima
T
T
Ito
A
A
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000378:metabolism*; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D006801:Humans; D007700:Kinetics; D008291:Malate Dehydrogenase / Q000378:metabolism; D008666:Metalloendopeptidases / Q000378:metabolism*; D008969:Molecular Sequence Data; D009953:Ornithine-Oxo-Acid Transaminase / Q000378:metabolism; D051381:Rats; D013379:Substrate Specificity; D000096122:Mitochondrial Processing Peptidase
D000596:Amino Acids; D008291:Malate Dehydrogenase; D008666:Metalloendopeptidases; D009953:Ornithine-Oxo-Acid Transaminase; D000096122:Mitochondrial Processing Peptidase