title: GTPase-mediated activation of ATP sulfurylase.
abstract: GTP stimulates the synthesis of APS (adenosine 5'-phosphosulfate) by the enzyme ATP sulfurylase (ATP:sulfate adenylyltransferase, EC 2.7.7.4) via a GTPase mechanism. The activation of the enzyme, purified from Escherichia coli, is titratable with GTP. The initial rate of APS formation is increased 116-fold at a saturating concentration of GTP. The enzyme exhibits a GTPase activity that is stimulated by ATP and further enhanced by SO4; however, SO4 alone does not significantly stimulate GTP hydrolysis. The larger subunit of ATP sulfurylase, encoded by cysN, contains a GTP-binding consensus sequence common to other known GTP-binding proteins. This is the first evidence that the sulfate activation pathway is a metabolic target for regulation by a GTPase.
authors.affiliation: Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461.
authors.forename: T S
authors.initials: TS
authors.lastname: Leyh
authors.forename: Y
authors.initials: Y
authors.lastname: Suo
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D015180:Electrophoresis, Gel, Two-Dimensional; D004789:Enzyme Activation; D004926:Escherichia coli / Q000201:enzymology; D020558:GTP Phosphohydrolases / Q000378:metabolism*; D006160:Guanosine Triphosphate / Q000378:metabolism; D006868:Hydrolysis; D008969:Molecular Sequence Data; D013379:Substrate Specificity; D013430:Sulfate Adenylyltransferase / Q000235:genetics / Q000378:metabolism*
chemical_list: D006160:Guanosine Triphosphate; D013430:Sulfate Adenylyltransferase; D020558:GTP Phosphohydrolases