Protein Stabilization by Removal of Unsatisfied Polar Groups: Computational Approaches and Experimental Tests
The role of polar and charged side chains in partially buried protein environments has been probed in a variant of Arc repressor (MYL) in which hydrophobic interactions between Met31, Tyr36, and Leu40 replace the wild-type salt-bridge interactions between Arg31, Glu36, and Arg40. In the absence of t...
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Published in | Biochemistry (Easton) Vol. 35; no. 24; pp. 7621 - 7625 |
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Main Authors | , , , |
Format | Journal Article |
Language | English |
Published |
United States
American Chemical Society
18.06.1996
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Subjects | |
Online Access | Get full text |
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Summary: | The role of polar and charged side chains in partially buried protein environments has been probed in a variant of Arc repressor (MYL) in which hydrophobic interactions between Met31, Tyr36, and Leu40 replace the wild-type salt-bridge interactions between Arg31, Glu36, and Arg40. In the absence of this salt-bridge triad, three additional side chains were identified by continuum electrostatic calculations as incurring larger desolvation penalties during folding than were recovered in favorable electrostatic interactions in the folded state. These side chains (Asn29, Ser44, and Glu48) were mutated singly and collectively to alanine in the MYL background, and the thermodynamic stabilities of the resulting mutant proteins were found to be increased by 0.1 to 1.3 kcal/mol of dimer. All of the mutants displayed cooperative thermal melts and appeared to have well-packed hydrophobic cores by near-UV circular dichroism spectroscopy, indicating that conformational specificity is maintained. The Arc variant (MYL-NA29/SA44/EA48) in which the entire six-residue polar network is replaced by nonpolar groups is 5.1 kcal/mol of dimer more stable than wild type, indicating that the strategy of replacing buried or partially buried charged and polar side chains with hydrophobic residues can lead to substantial stabilization. |
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Bibliography: | istex:D01FF74744305CA116B4859E4DA32D05BBACFE63 Abstract published in Advance ACS Abstracts, May 15, 1996. ark:/67375/TPS-MHRMGX9C-8 Supported by NIH Grants AI-15706 and GM-47678 and a Science Partnership grant from MIT. ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 |
ISSN: | 0006-2960 1520-4995 |
DOI: | 10.1021/bi9605191 |