2K7S

Human ARNT C-Terminal PAS Domain, 3 Residue IB slip

Summary for 2K7S

• Entry DOI: 10.2210/pdb2k7s/pdb
• Related: 1X0O
• NMR Information: BMRB: 15928
• Descriptor: Aryl hydrocarbon receptor nuclear translocator (1 entity in total)
• Functional Keywords: arnt pas-b, beta-strand slip, pas domain, activator, alternative splicing, dna-binding, nucleus, polymorphism, transcription, transcription regulation
• Biological source: Homo sapiens (human)
• Total number of polymer chains: 1
• Total formula weight: 13799.49

Authors

Evans, M.R.,Card, P.B.,Gardner, K.H. (deposition date: 2008-08-20, release date: 2009-01-20, Last modification date: 2024-05-08)

Primary citation

Evans, M.R.,Card, P.B.,Gardner, K.H.
ARNT PAS-B has a fragile native state structure with an alternative beta-sheet register nearby in sequence space
Proc.Natl.Acad.Sci.USA, 106:2617-2622, 2009

PubMed Abstract: The aryl hydrocarbon receptor nuclear translocator (ARNT) is a basic helix-loop-helix Period/ARNT/Single-minded (bHLH-PAS) protein that controls various biological pathways as part of dimeric transcriptional regulator complexes with other bHLH-PAS proteins. The two PAS domains within ARNT, PAS-A and PAS-B, are essential for the formation of these complexes because they mediate protein-protein interactions via residues located on their beta-sheet surfaces. While investigating the importance of residues in ARNT PAS-B involved in these interactions, we uncovered a point mutation (Y456T) on the solvent-exposed beta-sheet surface that allowed this domain to interconvert with a second, stable conformation. Although both conformations are present in equivalent quantities in the Y456T mutant, this can be shifted almost completely to either end point by additional mutations. A high-resolution solution structure of a mutant ARNT PAS-B domain stabilized in the new conformation revealed a 3-residue slip in register and accompanying inversion of the central Ibeta-strand. We have demonstrated that the new conformation has >100-fold lower in vitro affinity for its heterodimerization partner, hypoxia-inducible factor 2alpha PAS-B. We speculate that the pliability in beta-strand register is related to the flexibility required of ARNT to bind to several partners and, more broadly, to the abilities of some PAS domains to regulate their activities in response to small-molecule cofactors.

PubMed: 19196990
DOI: 10.1073/pnas.0808270106

Experimental method

SOLUTION NMR