The @entity5334 cofactor is ubiquitous in nature, and the pathway for Moco biosynthesis is conserved in all three domains of life. Recent work has helped to illuminate one of the most enigmatic steps in Moco biosynthesis, ligation of metal to molybdopterin (the organic component of the cofactor) to form the active cofactor. In @entity526 , the MoeA protein mediates ligation of Mo to molybdopterin while the MogA protein enhances this process in an @entity855 -dependent manner. The X-ray crystal structures for both proteins have been previously described as well as two essential MogA residues, @entity2574 49 and @entity2574 82. Here we describe a detailed mutational analysis of the MoeA protein. Variants of conserved residues at the putative active site of MoeA were analyzed for a loss of function in two different, previously described assays, one employing moeA- crude extracts and the other utilizing a defined system. Oddly, no correlation was observed between the activity in the two assays. In fact, our results showed a general trend toward an inverse relationship between the activity in each assay. Moco binding studies indicated a strong correlation between a variant's ability to bind Moco and its activity in the purified component assay. Crystal structures of the functionally characterized MoeA variants revealed no major structural changes, indicating that the functional differences observed are not due to disruption of the protein structure. On the basis of these results, two different functional areas were assigned to regions at or near the MoeA active site cleft.

Mutational analysis of XXXX MoeA: two functional activities map to the active site cleft.

@entity526 :: ('562', 'Species') :: ['Escherichia coli'] @entity855 :: ('MESH:D000255', 'Chemical') :: ['ATP'] @entity2574 :: ('CHEBI:22660', 'Chemical') :: ['Asp'] @entity5334 :: ('MESH:D008982', 'Chemical') :: ['molybdenum']
@entity526 :: (562,Species) :: ['Escherichia coli']
