PDBsum entry 1x0o

Transcription

PDB id: 1x0o

Contents

Protein chain

119 a.a. *

* Residue conservation analysis

PDB id:

1x0o

Name:

Transcription

Title:

Human arnt c-terminal pas domain

Structure:

Aryl hydrocarbon receptor nuclear translocator. Chain: a. Fragment: c-terminal pas domain. Synonym: arnt protein, dioxin receptor, nuclear translocator, hypoxia-inducible factor 1 beta, hif-1 beta

Source:

Homo sapiens. Human. Organism_taxid: 9606

NMR struc:

20 models

Authors:

P.B.Card,P.J.Erbel,K.H.Gardner

Key ref:

P.B.Card et al. (2005). Structural basis of ARNT PAS-B dimerization: use of a common beta-sheet interface for hetero- and homodimerization. J Mol Biol, 353, 664-677. PubMed id: 16181639 DOI: 10.1016/j.jmb.2005.08.043

Date:

25-Mar-05 Release date: 25-Oct-05

Protein chain

P27540  (ARNT_HUMAN) -  Aryl hydrocarbon receptor nuclear translocator from Homo sapiens

Seq: 789 a.a.

Struc: 119 a.a.*

* PDB and UniProt seqs differ at 3 residue positions (black crosses)

Enzyme reactions

• Enzyme class: E.C.?

DOI no: 10.1016/j.jmb.2005.08.043

J Mol Biol 353:664-677 (2005)

PubMed id: 16181639

Structural basis of ARNT PAS-B dimerization: use of a common beta-sheet interface for hetero- and homodimerization.

P.B.Card, P.J.Erbel, K.H.Gardner.

ABSTRACT

The aryl hydrocarbon receptor nuclear translocator (ARNT) is a promiscuous bHLH-PAS (Per-ARNT-Sim) protein that forms heterodimeric transcriptional regulator complexes with several other bHLH-PAS subunits to control a variety of biological pathways, some of which are centrally involved in disease initiation and/or progression. One of these is the hypoxia response pathway, which allows eukaryotic cells to respond to low oxygen tension via the formation of a heterodimeric complex between ARNT and another bHLH-PAS protein, the hypoxia-inducible factor alpha (HIF-alpha). We have previously shown that the C-terminal PAS domains of an HIF-alpha isoform (HIF-2alpha) and ARNT interact in vitro, and that mutations in the solvent-exposed beta-sheet surface of the HIF-2alpha domain not only disrupt this interaction, but also greatly attenuate the hypoxia response in living cells. Here, we have solved the solution structure of the corresponding PAS domain of ARNT and show that it utilizes a very similar interface for the interaction with the HIF-2alpha PAS domain. We also show that this domain self-associates in a concentration-dependent manner, and that the interface used in this homodimeric complex is very similar to that used in the formation of heterodimer. In addition, using experimentally derived NMR restraints, we used the program HADDOCK to calculate a low-resolution model of the complex formed in solution by these two PAS domains, and confirm the validity of this model using site-directed spin labeling to obtain long-range distance information in solution. With this information, we propose a model for the mode of multi-PAS domain interaction in bHLH-PAS transcriptional activation complexes.

Selected figure(s)

Figure 1.
Figure 1. Regulation of the hypoxia-inducible factor (HIF) by intracellular oxygen levels. Under normoxia, O[2]-dependent modifications target HIF-α subunits (green) for proteosomal degradation and interfere with their ability to interact with CBP/p300 transcriptional coactivators. Under the low O[2] levels of hypoxic conditions, HIF-α monomers are stabilized and transported to the nucleus where they form functional heterodimers with ARNT (blue) on hypoxia-responsive elements (HREs), upregulating gene transcription via the activity of their transcriptional activation domains (TADs, including ARNT TAD and HIF-α N and C-terminal TADs (NTAD and CTAD, respectively)).

Figure 4.
Figure 4. HADDOCK-derived structure of the HIF-2a/ARNT PAS-B domain complex. (a) Superposition of 20 lowest energy structures of the HIF-2a/ARNT PAS-B complex, with HIF-2a shown in green and ARNT in blue. The structure closest to the mean is highlighted with a tube representation for the backbone, and yellow sticks indicate the locations of the side-chains of three HIF-2a PAS-B residues previously shown to be critical for heterodimer formation and HIF-driven transcriptional activation.15^ and 16 (b) Ribbon diagram of the lowest energy complex structure (backbone r.m.s.d.=1.05(±0.31) Å for ordered residues 242-342 for HIF-2a and 361-445, 456-463 for ARNT PAS-B, relative to other members of ensemble). Backbone amide sites that display significant changes in chemical shift or intensity upon complex formation (shown as spheres) define the primary interface used for the HADDOCK calculations.

The above figures are reprinted by permission from Elsevier: J Mol Biol (2005, 353, 664-677) copyright 2005.

Figures were selected by the author.