Mitochondrial cysteine-specific aminoacyl-tRNA synthetase that catalyzes the ATP-dependent ligation of cysteine to tRNA(Cys). ; In addition to its role as an aminoacyl-tRNA synthetase, has also cysteine persulfide synthase activity. Produces reactive persulfide species such as cysteine persulfide (CysSSH) from substrate cysteine and mediate direct incorporation of CysSSH into proteins during translations, resulting in protein persulfides and polysulfides (PubMed:29079736). CysSSHs behave as potent antioxidants and cellular protectants (PubMed:29079736).
