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Publication Abstract from PubMed

HAP1 is a member of a family of fungal transcription factors that contain a Zn2Cys6 binuclear cluster domain and bind as homodimers to sequences containing two DNA half sites. We have determined the 2.5 A crystal structure of HAP1 bound to a cognate upstream activation sequence from the CYC7 gene. The structure reveals that HAP1 is bound in a dramatically asymmetric manner to the DNA target. This asymmetry aligns the Zn2Cys6 domains in a tandem head-to-tail fashion to contact two DNA half sites, positions an N-terminal arm of one of the protein subunits to interact with the inter-half site base pairs in the DNA minor groove, and suggests a mechanism by which DNA-binding facilitates asymmetric dimerization by HAP1. Comparisons with the DNA complexes of the related GAL4, PPR1 and PUT3 proteins illustrate how a conserved protein domain can be reoriented to recognize DNA half sites of different polarities and how homodimeric proteins adopt dramatically asymmetric structures to recognize cognate DNA targets.

Structure of a HAP1-DNA complex reveals dramatically asymmetric DNA binding by a homodimeric protein.,King DA, Zhang L, Guarente L, Marmorstein R Nat Struct Biol. 1999 Jan;6(1):64-71. PMID:9886294^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.