Based on our recent work with @entity6898 , ubiquitin-like (Ubl) proteins (SAMP1 and SAMP2) are known to be covalently attached to proteins in archaea. Here, we investigated the enzymes required for the formation of these Ubl-protein conjugates (SAMPylation) and whether this system is linked to @entity599 transfer. Markerless in-frame deletions were generated in @entity6898 target genes. The mutants were examined for: (i) the formation of Ubl protein conjugates, (ii) growth under various conditions, including those requiring the synthesis of the @entity599 -containing @entity5334 cofactor ( @entity70095 ), and (iii) the thiolation of tRNA. With this approach we found that UbaA of the E1/MoeB/ThiF superfamily was required for the formation of both SAMP1- and SAMP2-protein conjugates. In addition, UbaA, SAMP1, and MoaE (a homolog of the large subunit of molybdopterin synthase) were essential for @entity70095 -dependent @entity3733 reductase activity, suggesting that these proteins function in @entity70095 -biosynthesis. UbaA and SAMP2 were also crucial for optimal growth at high temperature and the thiolation of tRNA. Based on these results, we propose a working model for archaea in which the E1-like UbaA can activate multiple Ubl SAMPs for protein conjugation as well as for @entity599 transfer. In @entity599 transfer, SAMP1 and SAMP2 appear specific for @entity70095 biosynthesis and the thiolation of tRNA, respectively. Overall, this study provides a fundamental insight into the diverse cellular functions of the Ubl system.

E1- and ubiquitin-like proteins provide a direct link between protein conjugation and XXXX transfer in archaea.

@entity6898 :: ('2246', 'Species') :: ['H. volcanii', 'Haloferax volcanii'] @entity3733 :: ('MESH:D004121', 'Chemical') :: ['dimethyl sulfoxide'] @entity70095 :: ('CHEBI:21437', 'Chemical') :: ['MoCo'] @entity599 :: ('MESH:D013455', 'Chemical') :: ['sulfur'] @entity5334 :: ('MESH:D008982', 'Chemical') :: ['molybdenum']
@entity599 :: (MESH:D013455,Chemical) :: ['sulfur']
