3KTA: Structural Basis For Adenylate Kinase Activity In Abc Atpases

ATP-binding cassette (ABC) enzymes are involved in diverse biological processes ranging from transmembrane transport to chromosome cohesion and DNA repair. They typically use ATP hydrolysis to conduct energy-dependent biological reactions. However, the cystic fibrosis transmembrane conductance regulator and the DNA repair protein Rad50 can also catalyze the adenylate kinase reaction (ATP+AMP<-->2ADP). To clarify and provide a mechanistic basis for the adenylate kinase activity of ABC enzymes, we report the crystal structure of the nucleotide-binding domain of the Pyrococcus furiosus structural maintenance of chromosome protein (pfSMC(nbd)) in complex with the adenylate kinase inhibitor P(1),P(5)-di(adenosine-5')pentaphosphate. We show that pfSMC(nbd) possesses reverse adenylate kinase activity. Our results suggest that in adenylate kinase reactions, ATP binds to its canonical binding site while AMP binds to the Q-loop glutamine and a hydration water of the Mg(2+) ion. Furthermore, mutational analysis indicates that adenylate kinase reaction occurs in the engaged pfSMC(nbd) dimer and requires the Signature motif for phosphate transfer. Our results explain how ATP hydrolysis and adenylate kinase reactions can be catalyzed by the same functional motifs within the structural framework of ABC enzymes. Thus, adenylate kinase activity is likely to be a latent activity in many ABC enzymes.
PDB ID: 3KTADownload
MMDB ID: 83049
PDB Deposition Date: 2009/11/24
Updated in MMDB: 2010/08
Experimental Method:
x-ray diffraction
Resolution: 1.63  Å
Source Organism:
Similar Structures:
Biological Unit for 3KTA: dimeric; determined by author and by software (PISA)
Molecular Components in 3KTA
Label Count Molecule
Proteins (2 molecules)
Chromosome Segregation Protein SMC(Gene symbol: PF_RS09310)
Molecule annotation
Chromosome Segregation Protein SMC(Gene symbol: PF_RS09310)
Molecule annotation
Chemicals (2 molecules)
* Click molecule labels to explore molecular sequence information.

Citing MMDB