An Altered-Specificity Mutation in a Human POU Domain Demonstrates Functional Analogy Between the POU-Specific Subdomain and Phage λ Repressor

The POU motif, conserved among a family of eukaryotic transcription factors, contains two DNA-binding domains: an N-terminal POU-specific domain (POUS) and a C-terminal homeodomain (POUHD). Surprisingly, POUSis similar in structure to the helix-turn-helix domains of bacteriophage repressor and Cro p...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 1994-04, Vol.91 (9), p.3887-3891
Main Authors: Jancso, Agnes, Botfield, Martyn C., Sowers, Lawrence C., Weiss, Michael A.
Format: Article
Language:English
Subjects:
Bacteriophages
Base Sequence
Binding Sites
Biochemistry
Chemical bases
DNA
DNA-Binding Proteins - chemistry
Gels
Genetic mutation
Helix-Loop-Helix Motifs
Humans
Hydrogen bonds
In Vitro Techniques
Molecular Sequence Data
Mutagenesis, Site-Directed
Octamer Transcription Factor-2
phage lambda
Protein Structure, Tertiary
Proteins
Purines
Repressor Proteins - chemistry
Structure-Activity Relationship
Transcription factors
Transcription Factors - chemistry
Viral Proteins
Viral Regulatory and Accessory Proteins
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Summary:The POU motif, conserved among a family of eukaryotic transcription factors, contains two DNA-binding domains: an N-terminal POU-specific domain (POUS) and a C-terminal homeodomain (POUHD). Surprisingly, POUSis similar in structure to the helix-turn-helix domains of bacteriophage repressor and Cro proteins. Such similarity predicts a common mechanism of DNA recognition. To test this prediction, we have studied the DNA-binding properties of the human Oct-2 POU domain by combined application of chemical synthesis and site-directed mutagenesis. The POUSfoot-print of DNA contacts, identified by use of modified bases, is analogous to those of bacteriophage repressor-operator complexes. Moreover, a loss-of-contact substitution in the putative POUSrecognition α-helix leads to relaxed specificity at one position in the DNA target site. The implied side chain-base contact is identical to that of bacteriophage repressor and Cro proteins. These results establish a functional analogy between the POUSand prokaryotic helix-turn-helix elements and suggest that their DNA specificities may be governed by a shared set of rules.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.91.9.3887