Structural insight of dopamine β-hydroxylase, a drug target for complex traits, and functional significance of exonic single nucleotide polymorphisms.
BACKGROUND
Human dopamine β-hydroxylase (DBH) is an important therapeutic target for complex traits. Several single nucleotide polymorphisms (SNPs) have also been identified in DBH with potential adverse physiological effect. However, difficulty in obtaining diffractable crystals and lack of a suitable template for modeling the protein has ensured that neither crystallographic three-dimensional structure nor computational model for the enzyme is available to aid rational drug design, prediction of functional significance of SNPs or analytical protein engineering.


RESULTS
Adequate biochemical information regarding human DBH, structural coordinates for peptidylglycine alpha-hydroxylating monooxygenase and computational data from a partial model of rat DBH were used along with logical manual intervention in a novel way to build an in silico model of human DBH. The model provides structural insight into the active site, metal coordination, subunit interface, substrate recognition and inhibitor binding. It reveals that DOMON domain potentially promotes tetramerization, while substrate dopamine and a potential therapeutic inhibitor nepicastat are stabilized in the active site through multiple hydrogen bonding. Functional significance of several exonic SNPs could be described from a structural analysis of the model. The model confirms that SNP resulting in Ala318Ser or Leu317Pro mutation may not influence enzyme activity, while Gly482Arg might actually do so being in the proximity of the active site. Arg549Cys may cause abnormal oligomerization through non-native disulfide bond formation. Other SNPs like Glu181, Glu250, Lys239 and Asp290 could potentially inhibit tetramerization thus affecting function.


CONCLUSIONS
The first three-dimensional model of full-length human DBH protein was obtained in a novel manner with a set of experimental data as guideline for consistency of in silico prediction. Preliminary physicochemical tests validated the model. The model confirms, rationalizes and provides structural basis for several biochemical data and claims testable hypotheses regarding function. It provides a reasonable template for drug design as well.
Department of Biochemistry, University of Delhi South Campus, New Delhi, India.
Abhijeet
A
Kapoor
Manish
M
Shandilya
Suman
S
Kundu
D000818:Animals; D020134:Catalytic Domain; D055598:Chemical Phenomena; D003300:Copper; D004299:Dopamine beta-Hydroxylase / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D015195:Drug Design; D004791:Enzyme Inhibitors / Q000378:metabolism / Q000494:pharmacology; D005091:Exons / Q000235:genetics*; D006801:Humans; D008958:Models, Molecular; D058990:Molecular Targeted Therapy; D020641:Polymorphism, Single Nucleotide; D055503:Protein Multimerization; D020836:Protein Structure, Quaternary; D015203:Reproducibility of Results; D013329:Structure-Activity Relationship
D004791:Enzyme Inhibitors; D003300:Copper; D004299:Dopamine beta-Hydroxylase