1PP7: Crystal Structure Of The T. Vaginalis Initiator Binding Protein Bound To The Ferredoxin Inr

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.
PDB ID: 1PP7Download
MMDB ID: 102579
PDB Deposition Date: 2003/6/16
Updated in MMDB: 2012/09
Experimental Method:
x-ray diffraction
Resolution: 2.45  Å
Source Organism:
synthetic construct
Similar Structures:
Biological Unit for 1PP7: trimeric; determined by author
Molecular Components in 1PP7
Label Count Molecule
Protein (1 molecule)
39 KDA Initiator Binding Protein
Molecule annotation
Nucleotides(2 molecules)
Ferredoxin INR
Molecule annotation
Ferredoxin INR
Molecule annotation
Chemicals (7 molecules)
* Click molecule labels to explore molecular sequence information.

Citing MMDB