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Publication Abstract from PubMed

Sulfate assimilation is a critical component of both primary and secondary metabolism. An essential step in this pathway is the activation of sulfate through adenylation by the enzyme ATP sulfurylase (ATPS), forming adenosine 5'-phosphosulfate (APS). Proteobacterial ATPS overcomes this energetically unfavorable reaction by associating with a regulatory G protein, coupling the energy of GTP hydrolysis to APS formation. To discover the molecular basis of this unusual role for a G protein, we biochemically characterized and solved the X-ray crystal structure of a complex between Pseudomonas syringae ATPS (CysD) and its associated regulatory G protein (CysN). The structure of CysN*D shows the two proteins in tight association; however, the nucleotides bound to each subunit are spatially segregated. We provide evidence that conserved switch motifs in the G domain of CysN allosterically mediate interactions between the nucleotide binding sites. This structure suggests a molecular mechanism by which conserved G domain architecture is used to energetically link GTP turnover to the production of an essential metabolite.

Molecular basis for G protein control of the prokaryotic ATP sulfurylase.,Mougous JD, Lee DH, Hubbard SC, Schelle MW, Vocadlo DJ, Berger JM, Bertozzi CR Mol Cell. 2006 Jan 6;21(1):109-22. PMID:16387658^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.