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Direct Detection of the Acetate-forming Activity of the Enzyme Acetate Kinase
Published on: December 19, 2011
Structural basis for adenylate kinase activity in ABC ATPases
Alfred Lammens1, Karl-Peter Hopfner
1Center for Integrated Protein Science and Gene Center, Department of Biochemistry, Ludwig-Maximilians University of Munich, Feodor-Lynen-Str. 25, 81377 Munich, Germany.
Journal of Molecular Biology
|July 6, 2010
Summary
Many ATP-binding cassette (ABC) enzymes exhibit latent adenylate kinase activity. Structural and mutational analyses reveal how these enzymes catalyze both ATP hydrolysis and adenylate kinase reactions using shared motifs.
Area of Science:
- Biochemistry
- Molecular Biology
- Structural Biology
Background:
- ATP-binding cassette (ABC) enzymes are crucial for diverse cellular processes, utilizing ATP hydrolysis for energy-dependent reactions.
- Some ABC enzymes, like cystic fibrosis transmembrane conductance regulator and Rad50, also possess adenylate kinase activity (ATP + AMP <--> 2 ADP).
Purpose of the Study:
- To elucidate the mechanistic basis for adenylate kinase activity in ABC enzymes.
- To investigate the structural and functional requirements for this dual catalytic capability.
Main Methods:
- Crystal structure determination of the Pyrococcus furiosus structural maintenance of chromosome protein nucleotide-binding domain (pfSMC(nbd)) complexed with an adenylate kinase inhibitor.
- Biochemical assays to demonstrate reverse adenylate kinase activity.
- Site-directed mutagenesis to probe the role of specific motifs in catalysis.
Main Results:
- The crystal structure revealed the binding sites for ATP and AMP during the adenylate kinase reaction.
- pfSMC(nbd) was shown to possess reverse adenylate kinase activity.
- Mutational analysis confirmed that the engaged pfSMC(nbd) dimer and the Signature motif are essential for adenylate kinase activity.
Conclusions:
- ABC enzymes can catalyze both ATP hydrolysis and adenylate kinase reactions via shared functional motifs.
- Adenylate kinase activity is likely an intrinsic, latent function present in numerous ABC enzymes.
- Understanding this dual activity provides insights into the broader functional repertoire of ABC transporters.
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