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Conserved structural features on protein surfaces: small exterior hydrophobic clusters
Journal of Molecular Biology
|June 2, 1995
Summary
Surface side-chain interactions, often overlooked, can stabilize protein structures. Small exterior hydrophobic clusters (SEHCs) help accommodate non-polar residues, potentially guiding protein folding and tertiary structure.
Area of Science:
- Structural Biology
- Protein Folding
- Biochemistry
Background:
- The role of surface side-chain interactions in protein tertiary structure is debated.
- Evidence suggests some protein surfaces organize into discrete, tightly packed clusters.
- These clusters may play a role in accommodating large, hydrophobic residues externally.
Purpose of the Study:
- To investigate the function of surface clusters in accommodating hydrophobic residues.
- To explore the structural significance of these clusters in protein folding.
- To identify and characterize small exterior hydrophobic clusters (SEHCs).
Main Methods:
- Detailed structural analysis of poplar plastocyanin.
- Comparative analysis of proteins with Greek key beta-sandwich topology.
- Identification of SEHCs in various protein classes, including the rop dimer.
Main Results:
- Poplar plastocyanin exhibits mechanisms limiting solvent accessibility of hydrophobic groups.
- A common type of cluster, SEHCs, substantially excludes hydrophobic residues from solvent.
- Analogous SEHCs are frequently found in topologically similar proteins, suggesting a conserved role.
Conclusions:
- SEHCs appear to have a significant structural role, potentially fixing beta-strand register and association during folding.
- These clusters are not limited to plastocyanin-like proteins and are found in other structures like four-helix bundles.
- Surface hydrophobic residue accommodation by SEHCs may introduce local order, contributing to tertiary structure stabilization.