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Two different neurodegenerative diseases caused by proteins with similar structures
1Department of Molecular Biology and Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
Summary
The downstream prion-like protein (Dpl) shares structural similarity with PrP(C) but has distinct functions and causes unique neurodegenerative diseases when overexpressed. Its solution structure reveals key differences despite their shared ancestry.
Area of Science:
- Neuroscience
- Structural Biology
- Genetics
Background:
- The downstream prion-like protein (Dpl) is a paralog of the cellular prion protein (PrP(C)).
- Dpl and PrP(C) share ~25% sequence identity but exhibit distinct physiological roles.
- Unlike PrP(C), Dpl does not support prion replication and its overexpression induces a different neurodegenerative disease.
Purpose of the Study:
- To determine the solution structure of a recombinant mouse Dpl fragment (residues 26-157).
- To compare the structure of Dpl with that of PrP(C) and understand their evolutionary divergence.
Main Methods:
- Recombinant expression of mouse Dpl fragment (residues 26-157).
- Nuclear Magnetic Resonance (NMR) spectroscopy for solution structure determination.
Main Results:
- The Dpl fragment possesses a globular domain with three alpha-helices and some beta-structure.
- Dpl shares a similar overall topology with PrP(C).
- Key structural differences include a kinked helix and altered beta-strand orientation in Dpl compared to PrP(C).
Conclusions:
- Despite originating from a single ancestral gene, Dpl and PrP(C) have significantly diverged in sequence and function.
- Structural similarities between Dpl and PrP(C) persist, but distinct structural features correlate with their different roles and disease pathologies.