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Buried water molecules in helical transmembrane proteins
1Department of Biology, University of Texas at San Antonio, San Antonio, Texas 78249, USA. Robert.Renthal@UTSA.edu
Protein Science : a Publication of the Protein Society
|December 22, 2007
Summary
Buried water molecules in helical transmembrane proteins are crucial for structural stability. These waters, found more often in TM proteins than soluble ones, are conserved and linked to disease mutations.
Area of Science:
- Structural biology
- Biophysics
- Molecular biology
Background:
- Helical transmembrane (TM) proteins are vital membrane components.
- The role of internal water molecules in protein structure and function is an active area of research.
- Previous studies have explored buried water in soluble proteins, but less is known about their specific role in TM proteins.
Purpose of the Study:
- To identify and characterize buried water molecules in helical TM protein structures.
- To compare the properties of buried water in TM proteins with those in water-soluble (WS) proteins.
- To investigate the functional and evolutionary significance of buried water in TM proteins.
Main Methods:
- Analysis of 30 helical TM protein structures.
- Identification and quantification of buried water molecules.
- Characterization of water-protein contacts and their distribution within the membrane.
- Comparison with existing data for water-soluble proteins.
Main Results:
- Buried water is as abundant in helical TM proteins as in all WS proteins, and more abundant than in helical WS proteins.
- Buried waters in TM proteins form more polar contacts and interact more with helices compared to WS proteins.
- The distribution of buried water sites suggests a correlation with protein function and shows asymmetry, with more sites in the extracellular half.
- Conserved buried water contact sites across protein families, even with different functions, indicate a structural stabilization role.
- Disease-causing mutations occur more frequently at buried water contact sites, further supporting their stabilizing role.
Conclusions:
- Buried water molecules play a significant structural stabilization role in helical TM proteins.
- The unique characteristics and distribution of buried water in TM proteins are linked to their function and membrane environment.
- Conserved buried water sites and their association with disease mutations highlight their importance in TM protein integrity.
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