PDBsum entry 1f93

Transcription

PDB id: 1f93

Contents

Protein chains

103 a.a. *

31 a.a. *

27 a.a. *

27 a.a. *

26 a.a. *

Waters ×62

* Residue conservation analysis

References listed in PDB file

Key reference

Title

Structural basis of dimerization, Coactivator recognition and mody3 mutations in hnf-1alpha.

Authors

R.B.Rose, J.H.Bayle, J.A.Endrizzi, J.D.Cronk, G.R.Crabtree, T.Alber.

Ref.

Nat Struct Biol, 2000, 7, 744-748. [DOI no: 10.1038/78966]

PubMed id

10966642

Abstract

Maturity-onset diabetes of the young type 3 (MODY3) results from mutations in the transcriptional activator hepatocyte nuclear factor-1alpha (HNF-1alpha). Several MODY3 mutations target the HNF-1alpha dimerization domain (HNF-p1), which binds the coactivator, dimerization cofactor of HNF-1 (DCoH). To define the mechanism of coactivator recognition and the basis for the MODY3 phenotype, we determined the cocrystal structure of the DCoH-HNF-p1 complex and characterized biochemically the effects of MODY3 mutations in HNF-p1. The DCoH-HNF-p1 complex comprises a dimer of dimers in which HNF-p1 forms a unique four-helix bundle. Through rearrangements of interfacial side chains, a single, bifunctional interface in the DCoH dimer mediates both HNF-1alpha binding and formation of a competing, transcriptionally inactive DCoH homotetramer. Consistent with the structure, MODY3 mutations in HNF-p1 reduce activator function by two distinct mechanisms.

Figure 1.
Figure 1. Stereo view of the experimental, MAD-phased 2.6 Å resolution, electron density map contoured at 1 superimposed on the refined model. Residues 8 -11 in helix 1 of HNF-p1 and the interacting amino acids of the DCoH dimer (residues 55 -57 and 43' -46', where primes denote residues in the neighboring subunit) are shown.

Figure 2.
Figure 2. Structure of the DCoH -HNF-p1 complex. a, The DCoH dimer (yellow and orange) binds the HNF-p1 dimer (light and dark blue) with two helix 2 sequences of DCoH in contact with two helix 1 sequences of HNF-p1. The two-fold rotation axes of the dimers coincide (arrow). b, The bound HNF-p1 dimer (light and dark blue) forms an antiparallel four-helix bundle. The view is along the two-fold rotation axis (+) with the DCoH binding surface in front. Seven Leu side chains in each monomer stabilize the dimer and make contacts with DCoH. Red spheres mark two residues mutated in MODY3 patients, Leu 12 and Gly 20. The site of a third MODY3 mutation, Gly 31, occurs in the disordered region of the chain beyond residue 30. c, Electrostatic potential displayed on the surface of the recognition helices of DCoH (red, <-2.5 kT/e; white, -2.5 to 2.5 kT/e; and blue, >2.5 kT/e). A stick representation of helix 1 of the HNF-p1 dimer (light blue) is superimposed on the surface. d, The corresponding electrostatic potential displayed on the surface of the HNF-1 recognition helices. A stick representation of the recognition helices of the bound DCoH (yellow) is superimposed. The two surfaces in (c) and (d) match through a 180° rotation about a central, vertical axis. Complementary positive (DCoH) and negative (HNF-p1) potentials are evident on the left and right edges of the two interfaces. e, Interactions between DCoH (yellow and orange) and HNF-p1 (light and dark blue), viewed along the DCoH helical axes. Only half of each helix is shown, because the interactions in the other half are identical. Hydrophobic residues forming the core of the interface are displayed in gray. Side chains within hydrogen bonding distance are connected by lines. DCoH Glu 58' caps the N-terminus of the HNF-p1 helix 1, the Leu 8 amide, and forms a hydrogen bond with Ser 6. DCOH Lys 59' forms a hydrogen bond to the C-terminus of the neighboring HNF-p1 helix, the carbonyl of Ser 19'.

The above figures are reprinted by permission from Macmillan Publishers Ltd: Nat Struct Biol (2000, 7, 744-748) copyright 2000.

Secondary reference #1

Title

Crystal structure of dcoh, A bifunctional, Protein-Binding transcriptional coactivator.

Authors

J.A.Endrizzi, J.D.Cronk, W.Wang, G.R.Crabtree, T.Alber.

Ref.

Science, 1995, 268, 556-559. [DOI no: 10.1126/science.7725101]

PubMed id

7725101

Secondary reference #2

Title

High-Resolution structures of the bifunctional enzyme and transcriptional coactivator dcoh and its complex with a product analogue.

Authors

J.D.Cronk, J.A.Endrizzi, T.Alber.

Ref.

Protein Sci, 1996, 5, 1963-1972. [DOI no: 10.1002/pro.5560051002]

PubMed id

8897596

Figure 1.
Fig. 1. A: Metabolic ycle involving DCoH. DCoH catalyzes dehydration of a pterin-4a-carbinolamine cofactor, onverting 4a-hydroxytetrahydro- biopterin (4a-OH-Bb)to quinoid dihydrobiopterin (q-BH2). The q-BH2 is reduced by dihydropteridine reductase (DHPR) and the product, tetrahydro- biopterin (BH4). s used by the aromatic amino acid hydroxylases [e.g., phenylalanine hydroxylase (PAH)]. Names f pterin substrates areen- closed in ovals; enzymes are in boxes. The numbering system for pterins is shown or 4a-OH-BH4. Structure f the product analogue7,8- dihydrobiopterin (7,8-BH2). R, dihydroxypropyl.

Figure 6.
Fig. 6. Schematic ofthe proposeddehydratasemechanismsbased on the structure oftheDCoH17.8-BHz complex. A: Eliinationofwaterfrom a neutralreactant.Protondonationtothehydroxylleavinggroupandproton abstractionfom 5 ay ccur in a stepwise(notshown) or concerted mechanism. B: Elimination of aterfromananionicreactant. For proton transfersleadtodehydrationofthsubstrate.His 63 abstractstheproton on N8 ofthe pterinring (l), leading o theformation ofan anionispecies (2). An acidicgroup(AH:His 62, His 0, or water)donates a protontothe hydroxylleavinggroup,theimine (3) deprotonatestoyieldtheanionic product 4). and N8 isprotonatedtoyieldtheneutralproduct(q-BH2) (5). Thegeneralacid (HA) nd generalbase (B) couldcorrespondtothesame chemicalgroups,andthedehydraion can bestepwise concerted. His 62 occurs onthesame ofthe ring as the N5 proton,supporting a roleas a generalbase.

The above figures are reproduced from the cited reference which is an Open Access publication published by the Protein Society