Nucleotide sequence for cDNA of bovine mitochondrial ATP-dependent protease and determination of N-terminus of the mature enzyme from the adrenal cortex

Abstract

We have determined the cDNA sequence encoding bovine mitochondrial ATP-dependent Lon protease. Since the 5′-end region of the cDNA was highly GC-rich and thus could not be amplified by the 5′-RACE method, a genomic DNA fragment containing an in-frame ATG was isolated and sequenced. The translated amino acid sequence contained 961 amino acids with a calculated molecular weight 106,665. Sequence similarities of the bovine enzyme to human and E. coli orthologs were 92 and 27%, respectively. The N-terminal amino acid sequence seemed to be a mitochondrial targeting signal. To determine the cleavage site of the signal sequence we analyzed the mature enzyme purified from bovine adrenocortical mitochondria. Analysis of CNBr-digested peptides revealed that the N-terminus was heterogeneous. We suggest that nonspecific aminopeptidase might remove several amino acids from the N-terminus after mitochondrial processing peptidase has cleaved Gly⁶⁷–Leu⁶⁸ or Leu⁶⁸–Trp⁶⁹.

• ATP-dependent protease
• mitochondria
• mitochondrial targeting signal
• presequence
• processing
• AB208555
• AB208556