1XNJ: Aps Complex Of Human Paps Synthetase 1

The high energy sulfate donor 3'-phosphoadenosine-5-phosphosulfate (PAPS) is used for sulfate conjugation of extracellular matrix, hormones and drugs. Human PAPS synthetase 1 catalyzes two subsequent reactions starting from ATP and sulfate. First the ATP sulfurylase domain forms APS, then the APS kinase domain phosphorylates the APS intermediate to PAPS. Up to now the interaction between the two enzymatic activities remained elusive, mainly because of missing structural information. Here we present the crystal structure of human PAPSS1 at 1.8 angstroms resolution. The structure reveals a homodimeric, asymmetric complex with the shape of a chair. The two kinase domains adopt different conformational states, with only one being able to bind its two substrates. The asymmetric binding of ADP to the APS kinase is not only observed in the crystal structure, but can also be detected in solution, using an enzymatic assay. These observations strongly indicate structural changes during the reaction cycle. Furthermore crystals soaked with ADP and APS could be prepared and the corresponding structures could be solved.
PDB ID: 1XNJDownload
MMDB ID: 34649
PDB Deposition Date: 2004/10/5
Updated in MMDB: 2017/11
Experimental Method:
x-ray diffraction
Resolution: 1.98  Å
Source Organism:
Similar Structures:
Biological Unit for 1XNJ: dimeric; determined by author and by software (PISA)
Molecular Components in 1XNJ
Label Count Molecule
Proteins (2 molecules)
Bifunctional 3'-phosphoadenosine 5'-phosphosulfate Synthetase 1(Gene symbol: PAPSS1)
Molecule annotation
Chemicals (4 molecules)
* Click molecule labels to explore molecular sequence information.

Citing MMDB