1mh4
From Proteopedia
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maltose binding-a1 homeodomain protein chimera, crystal form II
Overview
The Yeast MATa1 and MATalpha2 are homeodomain proteins that bind DNA, cooperatively to repress transcription of cell type specific genes. The, DNA affinity and specificity of MATa1 in the absence of MATalpha2, however, is very low. MATa1 is converted to a higher affinity DNA-binding, protein by its interaction with the C-terminal tail of MATalpha2. To, understand why MATa1 binds DNA weakly by itself, and how the MATalpha2, tail affects the affinity of MATa1 for DNA, we determined the crystal, structure of a maltose-binding protein (MBP)-a1 chimera whose DNA binding, behavior is similar to MATa1. The overall MATa1 conformation in the MBP-a1, structure, which was determined in the absence of alpha2 and DNA, is, similar to that in the a1/alpha2/DNA structure. The sole difference is in, the C-terminal portion of the DNA recognition helix of MATa1, which is, flexible in the present structure. However, these residues are not in a, location likely to be affected by binding of the MATalpha2 tail. The, results argue against conformational changes in a1 induced by the tail of, MATalpha2, suggesting instead that the MATalpha2 tail energetically, couples the DNA binding of MATalpha2 and MATa1.
About this Structure
1MH4 is a Single protein structure of sequence from Escherichia coli and saccharomyces cerevisiae. Full crystallographic information is available from OCA.
Reference
Insights into binding cooperativity of MATa1/MATalpha2 from the crystal structure of a MATa1 homeodomain-maltose binding protein chimera., Ke A, Wolberger C, Protein Sci. 2003 Feb;12(2):306-12. PMID:12538894
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