1le8
Crystal Structure of the MATa1/MATalpha2-3A Heterodimer Bound to DNA Complex
OverviewOverview
Triply mutated MATalpha2 protein, alpha2-3A, in which all three major groove-contacting residues are mutated to alanine, is defective in binding DNA alone or in complex with Mcm1 yet binds with MATa1 with near wild-type affinity and specificity. To gain insight into this unexpected behavior, we determined the crystal structure of the a1/alpha2-3A/DNA complex. The structure shows that the triple mutation causes a collapse of the alpha2-3A/DNA interface that results in a reorganized set of alpha2-3A/DNA contacts, thereby enabling the mutant protein to recognize the wild-type DNA sequence. Isothermal titration calorimetry measurements reveal that a much more favorable entropic component stabilizes the a1/alpha2-3A/DNA complex than the alpha2-3A/DNA complex. The combined structural and thermodynamic studies provide an explanation of how partner proteins influence the sequence specificity of a DNA binding protein.
About this StructureAbout this Structure
1LE8 is a Protein complex structure of sequences from Saccharomyces cerevisiae. Full crystallographic information is available from OCA.
ReferenceReference
Structural and thermodynamic characterization of the DNA binding properties of a triple alanine mutant of MATalpha2., Ke A, Mathias JR, Vershon AK, Wolberger C, Structure. 2002 Jul;10(7):961-71. PMID:12121651 Page seeded by OCA on Fri May 2 23:50:16 2008