Conserved rhodopsin intradiscal structural motifs mediate stabilization: effects of zinc.

Abstract

Retinitis pigmentosa (RP), a neurodegenerative disorder, can arise from single point mutations in rhodopsin, leading to a cascade of protein instability, misfolding, aggregation, rod cell death, retinal degeneration, and ultimately blindness. Divalent cations, such as zinc and copper, have allosteric effects on misfolded aggregates of comparable neurodegenerative disorders including Alzheimer disease, prion diseases, and ALS. We report that two structurally conserved low-affinity zinc coordination motifs, located among a cluster of RP mutations in the intradiscal loop region, mediate dose-dependent rhodopsin destabilization. Disruption of native interactions involving histidines 100 and 195, through site-directed mutagenesis or exogenous zinc coordination, results in significant loss of receptor stability. Furthermore, chelation with EDTA stabilizes the structure of both wild-type rhodopsin and the most prevalent rhodopsin RP mutation, P(23)H. These interactions suggest that homeostatic regulation of trace metal concentrations in the rod outer segment of the retina may be important both physiologically and for an important cluster of RP mutations. Furthermore, with a growing awareness of allosteric zinc binding domains on a diverse range of GPCRs, such principles may apply to many other receptors and their associated diseases.

• Authors: Scott Gleim, Aleksandar Stojanovic, Eric Arehart, Daniel Byington, John Hwa
• Journal: Biochemistry (Biochemistry) Vol. 48 Issue 8 Pg. 1793-800 (Mar 03 2009) ISSN: 1520-4995 [Electronic] United States
• PMID: 19206210 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)

Chemical References

• Chelating Agents
• Mutant Proteins
• Opsins
• Histidine
• Rhodopsin
• Zinc

Topics

• Amino Acid Motifs
• Amino Acid Sequence
• Chelating Agents (pharmacology)
• Conserved Sequence
• Crystallography, X-Ray
• Histidine (metabolism)
• Humans
• Hydrogen Bonding (drug effects)
• Molecular Sequence Data
• Mutant Proteins (chemistry, metabolism)
• Mutation (genetics)
• Opsins (metabolism)
• Protein Stability (drug effects)
• Retinitis Pigmentosa (genetics)
• Rhodopsin (chemistry, metabolism)
• Sequence Analysis, Protein
• Temperature
• Time Factors
• Zinc (metabolism, pharmacology)