1HWT

Structure of a HAP1-DNA complex reveals dramatically asymmetric DNA binding by a homodimeric protein.

(1999) Nat Struct Biol 6: 64-71

• PubMed: 9886294 Search on PubMed
• DOI: https://doi.org/10.1038/4940
• Primary Citation of Related Structures:  
  1HWT


• PubMed Abstract: 
  

  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.

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Organizational Affiliation: 

The Wistar Institute and The Department of Chemistry, University of Pennsylvania, Philadelphia 19104, USA.