Adenylyltransferase involved in the biosynthesis of several sulfur compounds. Is required for the 2-thiolation of 5-methyluridine residue at position 54 in the T loop of tRNAs, leading to 5-methyl-2-thiouridine (m(5)s(2)U or s(2)T). This modification allows thermal stabilization of tRNAs in thermophilic microorganisms, and is essential for cell growth at high temperatures. TtuC catalyzes the adenylation by ATP of the carboxyl group of the C-terminal glycine of sulfur carrier protein TtuB. Is also involved in the biosynthesis of thiamine, molybdenum cofactor (Moco) and probably tungsten cofactor (Wco), by adenylating the sulfur carriers ThiS and MoaD (PubMed:19037260). Is required for the conjugation of TtuB to target proteins (PubMed:22467871). [molybdopterin-synthase sulfur-carrier protein]-C-terminal Gly-Gly + ATP + H(+) = [molybdopterin-synthase sulfur-carrier protein]-C-terminal Gly-Gly-AMP + diphosphate [sulfur-carrier protein ThiS]-C-terminal Gly-Gly + ATP + H(+) = [sulfur-carrier protein ThiS]-C-terminal Gly-Gly-AMP + diphosphate [TtuB sulfur-carrier protein]-C-terminal Gly-Gly + ATP + H(+) = [TtuB sulfur-carrier protein]-C-terminal Gly-Gly-AMP + diphosphate Binds 1 zinc ion per subunit. Enzymatic activity may be regulated by TtuB conjugation. tRNA modification. Cofactor biosynthesis; thiamine diphosphate biosynthesis. Cofactor biosynthesis; molybdopterin biosynthesis. Conjugated to TtuB via a covalent linkage that likely involves a lysine residue (PubMed:22467871). Is able to form a covalent thioester adduct with TtuB via Cys-192 in vitro (PubMed:19037260). Disruption of this gene completely abolishes the presence of m(5)s(2)U in tRNAs, although its precursor, 5-methyluridine (ribothymidine) is present; other nucleoside modifications remain unchanged (PubMed:19037260). These deletion mutants exhibit a temperature-sensitive phenotype similar to the ttuA and ttuB deletion mutants, they are unable to grow above 80 degrees Celsius (PubMed:19037260). They are also unable to synthesize thiamine and molybdenum cofactor (PubMed:19037260). No TtuB-protein conjugate is formed and only free TtuB is detected in the ttuC deletion strain (PubMed:22467871). Belongs to the HesA/MoeB/ThiF family.