PMID: 21628585

Authors:

Kim Y, Joachimiak G, Ye Z, Binkowski TA, Zhang R, Gornicki P, Callahan SM, Hess WR, Haselkorn R, Joachimiak A

Title:

Structure of transcription factor HetR required for heterocyst differentiation in cyanobacteria.

Journal:

Proc Natl Acad Sci U S A. 2011 Jun 21;108(25):10109-14. Epub 2011 May 31.

Abstract:

HetR is an essential regulator of heterocyst development in cyanobacteria. HetR binds to a DNA palindrome upstream of the hetP gene. We report the crystal structure of HetR from Fischerella at 3.0 A. The protein is a dimer comprised of a central DNA-binding unit containing the N-terminal regions of the two subunits organized with two helix-turn-helix motifs; two globular flaps extending in opposite directions; and a hood over the central core formed from the C-terminal subdomains. The flaps and hood have no structural precedent in the protein database, therefore representing new folds. The structural assignments are supported by site-directed mutagenesis and DNA-binding studies. We suggest that HetR serves as a scaffold for assembly of transcription components critical for heterocyst development.