Likely activates multiple ubiquitin-like SAMPs for protein conjugation as well as for sulfur transfer, via ATP-dependent adenylation at their C-terminus (PubMed:21368171, PubMed:24097257, PubMed:24906001). In fact, it is required for the formation of all three SAMP1-, SAMP2- and SAMP3-protein conjugates, and for molybdenum cofactor (MoCo) biosynthesis and thiolation of tRNAs (PubMed:21368171, PubMed:24097257). [small archaeal modifier protein]-C-terminal Gly-Gly + ATP + H(+) = [small archaeal modifier protein]-C-terminal Gly-Gly-AMP + diphosphate Binds 1 zinc ion per subunit. Interacts with NcsA. Sampylated at Lys-113 with the archaeal ubiquitin-like protein SAMP2. Also sampylated with SAMP1. Cells lacking this gene are deficient in sampylation, i.e. SAMP-protein conjugates. Moreover, they do not grow anaerobically with DMSO and do not show DMSO reductase activity, but their growth in the presence of oxygen is not affected; however, they are retarded in aerobic growth at 50 degrees Celsius. The lysine tRNAs of the mutant strain appear to be nonthiolated. Belongs to the HesA/MoeB/ThiF family.