A heterodimer of human 3'-phospho-adenosine-5'-phosphosulphate (PAPS) synthases is a new sulphate activating complex.
3'-Phospho-adenosine-5'-phosphosulphate (PAPS) synthases are fundamental to mammalian sulphate metabolism. These enzymes have recently been linked to a rising number of human diseases. Despite many studies, it is not yet understood how the mammalian PAPS synthases 1 and 2 interact with each other. We provide first evidence for heterodimerisation of these two enzymes by pull-down assays and Förster resonance energy transfer (FRET) measurements. Kinetics of dimer dissociation/association indicates that these heterodimers form as soon as PAPSS1 and -S2 encounter each other in solution. Affinity of the homo- and heterodimers were found to be in the low nanomolar range using anisotropy measurements employing proteins labelled with the fluorescent dye IAEDANS that--in spite of its low quantum yield--is well suited for anisotropy due to its large Stokes shift. Within its kinase domain, the PAPS synthase heterodimer displays similar substrate inhibition by adenosine-5'-phosphosulphate (APS) as the homodimers. Due to divergent catalytic efficacies of PAPSS1 and -S2, the heterodimer might be a way of regulating PAPS synthase function within mammalian cells.
Grum
Daniel
D
Structural and Medicinal Biochemistry, Centre for Medical Biotechnology - ZMB, Faculty of Biology and Geography, University of Duisburg-Essen, 45117 Essen, Germany. daniel.grum@uni-due.de
van den Boom
Johannes
J
Neumann
Daniel
D
Matena
Anja
A
Link
Nina M
NM
Mueller
Jonathan W
JW
D016880:Anisotropy; D004789:Enzyme Activation; D006801:Humans; D007527:Isoenzymes / Q000737:chemistry / Q000378:metabolism; D007700:Kinetics; D009097:Multienzyme Complexes / Q000737:chemistry* / Q000378:metabolism; D055503:Protein Multimerization; D013430:Sulfate Adenylyltransferase / Q000737:chemistry* / Q000378:metabolism; D013431:Sulfates / Q000737:chemistry* / Q000378:metabolism
D007527:Isoenzymes; D009097:Multienzyme Complexes; D013431:Sulfates; C022322:PAPS synthetase; D013430:Sulfate Adenylyltransferase