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Determination of the Neurospora crassa CYS 3 sulfur regulatory protein consensus DNA-binding site: amino-acid substitutions in the CYS3 bZIP domain that alter DNA-binding specificity.

Authors
  • Li, Q
  • Marzluf, G A
Type
Published Article
Journal
Current genetics
Publication Date
Sep 01, 1996
Volume
30
Issue
4
Pages
298–304
Identifiers
PMID: 8781172
Source
Medline
License
Unknown

Abstract

CYS3 is the positive-acting global regulatory protein involved in the sulfur control circuit in Neurospora crassa and belongs to the family of bZIP DNA-binding proteins. Here we report a characterization of native DNA-binding sites recognized by CYS3. DNA footprinting experiments and systematic mutational analysis were used to define the consensus CYS3-binding sequence, 5'-ATGPuPyPuPyCAT, a 10-bp palindrome. The sequence 5'-ATGACGTCAT acts as a strong binding site, and all single nucleotide changes within this sequence resulted in a reduction, or even complete loss, of CYS3 DNA-binding. Site-directed mutagenesis was employed to study two uncharged residues, serine 113 and phenylalanine 116, in the basic region of the CYS3 protein bZip DNA-binding domain. Ser113 appears to be directly involved in a specific interaction with nucleotide 2 of the binding site, possibly by making a direct contact with this base, and Phe116 contributes significantly to DNA-binding affinity.

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