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Chromodomains read the arginine code of post-translational targeting
Iris Holdermann1, N Helge Meyer, Adam Round
1Heidelberg University Biochemistry Center, Heidelberg, Germany.
Nature Structural & Molecular Biology
|January 11, 2012
Summary
The crystal structure reveals how chloroplast signal recognition particle (cpSRP) components interact. This finding explains a non-nuclear role for chromodomains in protein targeting within plant cells.
Area of Science:
- Molecular Biology
- Structural Biology
- Plant Cell Biology
Background:
- Chromodomains are known epigenetic readers, recognizing histone lysine methylation for protein complex recruitment to chromatin.
- The signal recognition particle (SRP) pathway is crucial for targeting proteins to organelles and the cell surface.
Purpose of the Study:
- To determine the crystal structure of the chloroplast signal recognition particle (cpSRP) core from Arabidopsis thaliana.
- To elucidate the molecular mechanism of interaction between cpSRP54 and cpSRP43.
Main Methods:
- X-ray crystallography was used to determine the high-resolution structure of the cpSRP core.
- Structural analysis focused on the interaction between the cpSRP54 tail and the cpSRP43 chromodomain.
Main Results:
- The crystal structure revealed the binding of the arginine-rich motif of the cpSRP54 tail to the second chromodomain of cpSRP43.
- A unique 'twinned aromatic cage' within the chromodomain was identified, which recognizes two neighboring nonmethylated arginines.
Conclusions:
- The identified interaction mechanism highlights an adaptation of chromodomains for a non-nuclear function in post-translational protein targeting.
- This structural insight provides a molecular basis for cpSRP-mediated protein transport in chloroplasts.
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