  2.7.7.100 | physiological function |
in archaea, E1-like enzymes, such as Haloferax volcanii UbaA, are central hubs that activate the Ubls for ligation to protein targets and for sulfur mobilization. UbaA is required for the Ubl small archaeal modifier proteins (SAMPs) to serve as protein modifiers and to carry sulfur to biomolecules. SAMP1 carries sulfur to form Moco, based on its binding to MoaE (the large subunit of molybdopterin [MPT] synthase) and its requirement for Moco-dependent dimethyl sulfoxide (DMSO) reductase activity. Haloferax volcanii UbaA is not fused to an RHD. The stand-alone rhodanese-like domain (RHD) protein UbaC (UniProt ID D4GTH6) plays a role in ubiquitin-like protein modification and sulfur mobilization in Archaea. UbaC of Haloferax volcanii binds the E1 UbaA and is required for Ubl modification and for functions associated with Ubl sulfur relay. UbaC and its conserved active-site cysteine(C64) are (i) required for DMSO respiration/reductase activity correlated with Moco biosynthesis, (ii) important for survival at elevated temperature, which is indicative of a functional wobble uridine tRNA thiolation pathway, and (iii) critical for the formation of Ubl ligation products, with marked exception of the SAMP1 conjugates induced by oxidative stress. E1-RHD relationship, detailed overview |
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