Role of the Occluded Conformation in Bacterial Dihydrofolate Reductases
| Autor: | Stella M. Matthews, Louis Y. P. Luk, Enas M. Behiry, Rudolf Konrad Allemann, Edric Joel Loveridge |
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| Jazyk: | angličtina |
| Rok vydání: | 2014 |
| Předmět: |
Models
Molecular Stereochemistry Protein Conformation medicine.disease_cause Biochemistry chemistry.chemical_compound Protein structure Bacterial Proteins Dihydrofolate reductase Enzyme Stability medicine Escherichia coli QD biology Hydrogen bond Mutagenesis Kinetics Tetrahydrofolate Dehydrogenase Catalytic cycle chemistry biology.protein Biocatalysis Mutagenesis Site-Directed Folic Acid Antagonists Steady state (chemistry) Oxidation-Reduction Nicotinamide adenine dinucleotide phosphate Moritella NADP |
| ISSN: | 0006-2960 |
| Popis: | Dihydrofolate reductase (DHFR) from Escherichia\ud coli (EcDHFR) adopts two major conformations, closed\ud and occluded, and movement between these two conformations\ud is important for progression through the catalytic cycle.\ud DHFR from the cold-adapted organism Moritella profunda\ud (MpDHFR) on the other hand is unable to form the two\ud hydrogen bonds that stabilize the occluded conformation in\ud EcDHFR and so remains in a closed conformation during\ud catalysis. EcDHFR-S148P and MpDHFR-P150S were examined\ud to explore the influence of the occluded conformation on\ud catalysis by DHFR. Destabilization of the occluded conformation did not affect hydride transfer but altered the affinity for the\ud oxidized form of nicotinamide adenine dinucleotide phosphate (NADP+) and changed the rate-determining step of the catalytic\ud cycle for EcDHFR-S148P. Even in the absence of an occluded conformation, MpDHFR follows a kinetic pathway similar to that\ud of EcDHFR with product release being the rate-limiting step in the steady state at pH 7, suggesting that MpDHFR uses a\ud different strategy to modify its affinity for NADP+. DHFRs from many organisms lack a hydrogen bond donor in the appropriate\ud position and hence most likely do not form an occluded conformation. The link between conformational cycling between closed\ud and occluded forms and progression through the catalytic cycle is specific to EcDHFR and not a general characteristic of\ud prokaryotic DHFR catalysis. |
| Databáze: | OpenAIRE |
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