1FMH

NMR SOLUTION STRUCTURE OF A DESIGNED HETERODIMERIC LEUCINE ZIPPER


Experimental Data Snapshot

  • Method: SOLUTION NMR
  • Conformers Calculated: 50 
  • Conformers Submitted: 25 
  • Selection Criteria: structures with the least restraint violations,structures with the lowest energy 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Interhelical ion pairing in coiled coils: solution structure of a heterodimeric leucine zipper and determination of pKa values of Glu side chains.

Marti, D.N.Jelesarov, I.Bosshard, H.R.

(2000) Biochemistry 39: 12804-12818

  • Also Cited By: 1U2U

  • PubMed Abstract: 
  • Residues of opposite charge often populate heptad positions g (heptad i on chain 1) and e' (heptad i + 1 on chain 2) in dimeric coiled coils and may stabilize the dimer by formation of interchain ion pairs. To investigate the contribution to stabilit ...

    Residues of opposite charge often populate heptad positions g (heptad i on chain 1) and e' (heptad i + 1 on chain 2) in dimeric coiled coils and may stabilize the dimer by formation of interchain ion pairs. To investigate the contribution to stability of such electrostatic interactions we have designed a disulfide-linked heterodimeric zipper (AB zipper) consisting of the acidic chain Ac-E-VAQLEKE-VAQAEAE-NYQLEQE-VAQLEHE-CG-NH(2) and the basic chain Ac-E-VQALKKR-VQALKAR-NYAAKQK-VQALRHK-CG-NH(2) in which all e and g positions are occupied by either E or K/R to form a maximum of seven interhelical salt bridges. Temperature-induced denaturation experiments monitored by circular dichroism reveal a stable coiled coil conformation below 50 degrees C and in the pH range 1.2-8.0. Stability is highest at pH approximately 4.0 [DeltaG(U) (37 degrees C) = 5.18 +/- 0.51 kcal mol(-)(1)]. The solution structure of the AB zipper at pH 5.65 has been elucidated on the basis of homonuclear (1)H NMR data collected at 800 MHz [heavy atom rmsd's for the ensemble of 50 calculated structures are 0.47 +/- 0.13 A (backbone) and 0.95 +/- 0.16 A (all)]. Both chains of the AB zipper are almost entirely in alpha-helical conformation and form a superhelix with a left-handed twist. Overhauser connectivities reveal close contacts between g position residues (heptad i on chain 1) and residues d/f (heptad i on chain 1), residues a/d (heptad i + 1 on chain 1), and residue a' (heptad i + 1 on chain 2). Residues in position e (heptad i on chain 1) are in contact with residues a/b/d/f (heptad i on chain 1) and residue d' (heptad i on chain 2). These connectivities hint at a relatively defined alignment of the side chains across the helix interface. Partial H-bond formation between the functional groups of residues g and e'(+1) is observed in the calculated structures. NMR pH titration experiments disclose pK(a) values for Glu delta-carboxylate groups: 4.14 +/- 0.02 (E(1)), 4.82 +/- 0.07 (E(6)), 4.52 +/- 0.01 (E(8)), 4.37 +/- 0.03 (E(13)), 4.11 +/- 0.02 (E(15)), 4.41 +/- 0.07 (E(20)), 4.82 +/- 0.03 (E(22)), 4.65 +/- 0.04 (E(27)), 4.63 +/- 0.03 (E(29)), 4.22 +/- 0.02 (E(1)(')). By comparison with pK(a) of Glu in unfolded peptides ( approximately 4. 3 +/- 0.1), our pK(a) data suggest marginal or even unfavorable contribution of charged Glu to the stability of the AB zipper. The electrostatic energy gained from interhelical ion pairs is likely to be surpassed by hydrophobic energy terms upon protonation of Glu, due to increased hydrophobicity of uncharged Glu and, thus, better packing against apolar residues at the chain interface.


    Related Citations: 
    • Extremely Fast Folding of a Very Stable Leucine Zipper with a Strengthened Hydrophobic Core and Lacking Electrostatic Interactions between Helices
      Durr, E.,Jelesarov, I.,Bosshard, H.R.
      (1999) Biochemistry 38: 870
    • Thermodynamic Characterization of the Coupled Folding and Association of Heterodimeric Coiled Coils (Leucine Zippers)
      Jelesarov, I.,Bosshard, H.R.
      (1996) J.Mol.Biol. 263: 344


    Organizational Affiliation

    Institute of Biochemistry, University of Zürich, CH-8057 Zürich, Switzerland. dmarti@acess.unizh.ch




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
GENERAL CONTROL PROTEIN GCN4
A
33Saccharomyces cerevisiae (strain ATCC 204508 / S288c)Gene Names: GCN4 (AAS3, ARG9)
Find proteins for P03069 (Saccharomyces cerevisiae (strain ATCC 204508 / S288c))
Go to UniProtKB:  P03069
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetails
GENERAL CONTROL PROTEIN GCN4
B
33Saccharomyces cerevisiae (strain ATCC 204508 / S288c)Gene Names: GCN4 (AAS3, ARG9)
Find proteins for P03069 (Saccharomyces cerevisiae (strain ATCC 204508 / S288c))
Go to UniProtKB:  P03069
Small Molecules
Modified Residues  2 Unique
IDChainsTypeFormula2D DiagramParent
NH2
Query on NH2
A, B
NON-POLYMERH2 N

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ACE
Query on ACE
A, B
NON-POLYMERC2 H4 O

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Experimental Data & Validation

Experimental Data

  • Method: SOLUTION NMR
  • Conformers Calculated: 50 
  • Conformers Submitted: 25 
  • Selection Criteria: structures with the least restraint violations,structures with the lowest energy 
  • Olderado: 1FMH Olderado

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2000-11-01
    Type: Initial release
  • Version 1.1: 2008-04-27
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance