May only reduce GSH-thiol disulfides, but not protein disulfides (Probable). Participates probably to the maturation of iron-sulfur proteins and to the regulation of the redox state of the BOLA proteins (Probable). The GRXS16-BOLA1 heterodimer binds a labile, oxygen sensitive iron-sulfur cluster (PubMed:24714563). Able to cleave linearized DNA in vitro (PubMed:23690600). The formation of an intramolecular disulfide bond negatively regulates both the N-terminal endonuclease and the C-terminal glutaredoxin activities. [2Fe-2S]-bridged holo-homodimer (PubMed:23690600). Interacts in vitro with SUFE1, BOLA1, BOLA2 and BOLA4 (PubMed:24203231). Interacts in vivo only with SUFE1, BOLA1 and BOLA4 (PubMed:24203231, PubMed:24714563, PubMed:23690600). Interacts with SBP1 (PubMed:30824043). The N-terminal domain (NTD) (63-170) has an intrinsic Mg(2+)-dependent endonuclease activity in vitro (PubMed:23690600). The glutaredoxin (GRX) domain (194-293) alone is able to complement yeast grx5 cells in vitro, but not the full-length GRXS16 protein. Belongs to the glutaredoxin family. CGFS subfamily.