Nucleotide binding site communication in Arabidopsis thaliana adenosine 5'-phosphosulfate kinase.

ABSTRACT: Adenosine 5'-phosphosulfate kinase (APSK) catalyzes the ATP-dependent synthesis of adenosine 3'-phosphate 5'-phosphosulfate (PAPS), which is an essential metabolite for sulfur assimilation in prokaryotes and eukaryotes. Using APSK from Arabidopsis thaliana, we examine the energetics of nucleotide binary and ternary complex formation and probe active site features that coordinate the order of ligand addition. Calorimetric analysis shows that binding can occur first at either nucleotide site, but that initial interaction at the ATP/ADP site was favored and enhanced affinity for APS in the second site by 50-fold. The thermodynamics of the two possible binding models (i.e. ATP first versus APS first) differs and implies that active site structural changes guide the order of nucleotide addition

SUBMITTER: Ravilious GE 

PROVIDER: S-EPMC3436368 | biostudies-literature | 2012 Aug

REPOSITORIES: biostudies-literature