PDBsum entry 1gw3

High density lipoproteins

PDB id: 1gw3

Contents

Protein chain

46 a.a. *

* Residue conservation analysis

PDB id:

1gw3

Name:

High density lipoproteins

Title:

The helix-hinge-helix structural motif in human apolipoprotein a-i determined by nmr spectroscopy, 1 structure

Structure:

Apoa-i. Chain: a. Fragment: residues 142 - 187. Synonym: apolipoprotein a-i. Engineered: yes

Source:

Homo sapiens. Human. Organism_taxid: 9606

NMR struc:

1 models

Authors:

G.Wang,J.T.Sparrow,R.J.Cushley

Key ref:

G.Wang et al. (1997). The helix-hinge-helix structural motif in human apolipoprotein A-I determined by NMR spectroscopy. Biochemistry, 36, 13657-13666. PubMed id: 9354635 DOI: 10.1021/bi971151q

Date:

04-Jun-97 Release date: 23-Jul-97

Protein chain

P02647  (APOA1_HUMAN) -  Apolipoprotein A-I from Homo sapiens

Seq: 267 a.a.

Struc: 46 a.a.

Enzyme reactions

• Enzyme class: E.C.?

DOI no: 10.1021/bi971151q

Biochemistry 36:13657-13666 (1997)

PubMed id: 9354635

The helix-hinge-helix structural motif in human apolipoprotein A-I determined by NMR spectroscopy.

G.Wang, J.T.Sparrow, R.J.Cushley.

ABSTRACT

The conformation of a synthetic peptide of 46 residues from apoA-I was investigated by fluorescence, CD, and 2D NMR spectroscopies in lipid-mimetic environments. ApoA-I(142-187) is mainly unstructured in water but helical in SDS or dodecylphosphocholine (DPC), although the peptide only associates with DPC at approximately the critical micellar concentration. Solution structures of apoA-I(142-187) were determined by distance geometry calculations based on 450 (in DPC-d38) or 397 (in SDS-d25) NOE-derived distance restraints, respectively. Backbone RMSDs for superimposing the two helical regions 146-162 and 168-182 are 0.98 +/- 0.22 (2.38 +/- 0.20) and 1.99 +/- 0.42 (2.02 +/- 0.21) A in DPC (SDS), respectively. No interhelical NOE was found, suggesting that helix-helix interactions between the two helical domains in apoA-I(142-187) are unlikely. Similar average, curved helix-hinge-helix structures were found in both SDS and DPC micelles with the hydrophobic residues occupying the concave face, indicating that hydrophobic interactions dominate. Intermolecular NOESY experiments, performed in the presence of 50% protonated SDS, confirm that the two amphipathic helices and Y166 in the hinge all interact with the micelle. The involvement of Y166 in lipid binding is supported by fluorescence spectroscopy as well. On the basis of all the data above, we propose a model for the peptide-lipid complexes wherein the curved amphipathic helix-hinge-helix structural motif straddles the micelle. The peptide-aided signal assignment achieved for apoA-I(122-187) (66mer) and apoA-I suggests that such a structural motif is retained in the longer peptide and most likely in the intact protein.