Cooperative Ordering in Homeodomain−DNA Recognition: Solution Structure and Dynamics of the MATa1 Homeodomain
The mating type homeodomain proteins, MATa1 and MATα2, combine to form a heterodimer to bind DNA in diploid yeast cells. The a1−α2 heterodimer tightly and specifically binds haploid-specific gene operators to repress transcription. On its own, however, the a1 homeodomain does not bind DNA in a seque...
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Published in | Biochemistry (Easton) Vol. 39; no. 33; pp. 10045 - 10054 |
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Main Authors | , , , , |
Format | Journal Article |
Language | English |
Published |
United States
American Chemical Society
22.08.2000
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Subjects | |
Online Access | Get full text |
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Summary: | The mating type homeodomain proteins, MATa1 and MATα2, combine to form a heterodimer to bind DNA in diploid yeast cells. The a1−α2 heterodimer tightly and specifically binds haploid-specific gene operators to repress transcription. On its own, however, the a1 homeodomain does not bind DNA in a sequence-specific manner. To help understand this interaction, we describe the solution structure and backbone dynamics of the free a1 homeodomain. Free a1 in solution is an ensemble of structures having flexible hinges at the two turns in the small protein fold. Conformational changes in the a1 homeodomain upon ternary complex formation are located in the loop between helix 1 and helix 2, where the C-terminal tail of α2 binds to form the heterodimer, and at the C-terminus of helix 3, the DNA recognition helix. The observed differences, comparing the free and bound a1 structures, suggest a mechanism linking van der Waals stacking changes to the ordering of a final turn in the DNA-binding helix of a1. The tail of α2 induces changes in loop 1 of a1 that push it toward a properly folded DNA binding conformation. |
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Bibliography: | ark:/67375/TPS-9KQBW25D-0 This work was supported by a grant from the National Institute of General Medical Sciences (GM55361) to S.M.B. istex:F2D644A0CB5780DC7F6DAECC66D956DD7DC2C497 ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 ObjectType-Article-1 ObjectType-Feature-2 |
ISSN: | 0006-2960 1520-4995 |
DOI: | 10.1021/bi000677z |