Probable ATP-dependent zinc metallopeptidase. Involved in the assembly and/or stability of the complex V of the mitochondrial oxidative phosphorylation system. Binds 1 zinc ion per subunit. Homooligomer. The complex formed by FTSH4 does not contain FTSH11. By high light. In contrast to fungi and metazoa, plant mitochondria have more than one i-AAA-like complexes. In the N-terminal section; belongs to the AAA ATPase family. In the C-terminal section; belongs to the peptidase M41 family.