4QFV image
Deposition Date 2014-05-21
Release Date 2015-05-06
Last Version Date 2023-09-20
Entry Detail
PDB ID:
4QFV
Keywords:
Title:
Crystal structure of a unique ankyrin
Biological Source:
Source Organism:
Method Details:
Experimental Method:
Resolution:
2.00 Å
R-Value Free:
0.22
R-Value Work:
0.17
R-Value Observed:
0.18
Space Group:
P 1 21 1
Macromolecular Entities
Polymer Type:polypeptide(L)
Molecule:ANK-N5C-281
Chain IDs:A, B, C, D
Chain Length:234
Number of Molecules:4
Biological Source:synthetic construct
Ligand Molecules
Primary Citation
A transcription blocker isolated from a designed repeat protein combinatorial library by in vivo functional screen.
Sci Rep 5 8070 8070 (2015)
PMID: 25627011 DOI: 10.1038/srep08070

Abstact

A highly diverse DNA library coding for ankyrin seven-repeat proteins (ANK-N5C) was designed and constructed by a PCR-based combinatorial assembly strategy. A bacterial melibiose fermentation assay was adapted for in vivo functional screen. We isolated a transcription blocker that completely inhibits the melibiose-dependent expression of α-galactosidase (MelA) and melibiose permease (MelB) of Escherichia coli by specifically preventing activation of the melAB operon. High-resolution crystal structural determination reveals that the designed ANK-N5C protein has a typical ankyrin fold, and the specific transcription blocker, ANK-N5C-281, forms a domain-swapped dimer. Functional tests suggest that the activity of MelR, a DNA-binding transcription activator and a member of AraC family of transcription factors, is inhibited by ANK-N5C-281 protein. All ANK-N5C proteins are expected to have a concave binding area with negative surface potential, suggesting that the designed ANK-N5C library proteins may facilitate the discovery of binders recognizing structural motifs with positive surface potential, like in DNA-binding proteins. Overall, our results show that the established library is a useful tool for the discovery of novel bioactive reagents.

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