Abstract
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.
Original language | English |
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Pages (from-to) | 420-5 |
Number of pages | 6 |
Journal | Biochemical and Biophysical Research Communications |
Volume | 395 |
Issue number | 3 |
DOIs | |
Publication status | Published - 7 May 2010 |
Keywords
- Anisotropy
- Enzyme Activation
- Humans
- Isoenzymes
- Kinetics
- Multienzyme Complexes
- Protein Multimerization
- Sulfate Adenylyltransferase
- Sulfates