1Q88

Crystal structure of the C-domain of the T.vaginalis Inr binding protein, IBP39 (monoclinic form)

Summary for 1Q88

• Entry DOI: 10.2210/pdb1q88/pdb
• Related: 1PP7 1PP8 1Q87 1Q89
• Descriptor: 39 kDa initiator binding protein (2 entities in total)
• Functional Keywords: initiator, core promoter, inr, dna binding protein
• Biological source: Trichomonas vaginalis
• Total number of polymer chains: 2
• Total formula weight: 51454.44

Authors

Schumacher, M.A.,Johnson, P.J. (deposition date: 2003-08-20, release date: 2003-11-18, Last modification date: 2024-02-14)

Primary citation

Schumacher, M.A.,Lau, A.O.T.,Johnson, P.J.
Structural Basis of Core Promoter Recognition in a Primitive Eukaryote
Cell(Cambridge,Mass.), 115:413-424, 2003

PubMed Abstract: Transcription start site selection in eukaryotes is mediated through combinations of the TATA, initiator (Inr), and downstream promoter elements (DPE). In Trichomonas vaginalis, a parabasalian flagellate thought to represent an ancient eukaryote lineage, the Inr appears to be solely responsible for start site selection and is recognized by the initiator binding protein 39 kDa (IBP39). IBP39 contains an N-terminal Inr binding domain (IBD) connected via a flexible linker to a C-terminal domain (C domain). Here we present crystal structures of the apoIBD and IBD-Inr complexes and the C domain. The IBD structures reveal a winged-helix motif with prokaryotic and eukaryotic features and a scaffold similar to that of ETS-family proteins. The C domain structure and biochemical studies indicate that it interacts with the T. vaginalis RNAP II large subunit C-terminal domain. These data suggest that binding of IBP39 to the Inr directly recruits RNAP II and in this way initiates transcription.

PubMed: 14622596
DOI: 10.1016/S0092-8674(03)00887-0

Experimental method

X-RAY DIFFRACTION (2.42 Å)