OMA1

Metalloendopeptidase OMA1, mitochondrial is an enzyme that in humans is encoded by the OMA1 gene. As a Metalloprotease, this protein is a substantial component of the quality control system in the inner membrane of mitochondria. Being activated by enzyme Bax and Bak, mitochondrial protease OMA1 promotes cytochrome c release which subsequently induces apoptosis.

Structure

Gene

The gene OMA1 encodes a metalloprotease, a founding member of a conserved family of membrane-embedded metallopeptidases in mitochondria. The human gene has 9 exons and locates at chromosome band 1p32.2-p32.1

Protein

The human protein Metalloendopetidase OMA1, mitochondrial is 60 kDa in size and composed of 524 amino acids. The peptide fragment 1-13 is mitochondrial transition peptide, the mature protein has a theoretical PI of 9.35.

Function

The inner membrane of mitochondrial houses two AAA proteases and these membrane-embedded peptidases were termed m- and i-AAA proteases to indicate their different topology in the inner membrane. The m-AAA protease is facing the matrix and the i-AAA protease is facing the intermembrane space. OMA1 was shown to share an overlapping proteolytic activity with m-AAA protease. However, OMA1 doesn't completely regulate the turnover of a model substrate, Oxa1, as what the m-AAA protease does. On the contrary, Oma1 only generates N- and C-terminal proteolytic fragments. Recent study showed that the mammalian mitochondrial inner membrane fusion protein OPA1 can be degraded by OMA1 when mitochondria lose membrane potential or adenosine triphosphate. Such inducible proteolysis acts as a regulatory mechanism to proteolytically inactivate of OPA1, thus preventing the fusion of the mitochondrial network.