TY - JOUR

T1 - Cross-beta spine architecture of fibrils formed by the amyloidogenic segment NFGSVQFV of medin from solid-state NMR and X-ray fiber diffraction measurements

AU - Madine, Jillian

AU - Copland, Alastair

AU - Serpell, Louise C

AU - Middleton, David A

PY - 2009/4/14

Y1 - 2009/4/14

N2 - Over 30 polypeptides are known to assemble into highly ordered fibrils associated with pathological disorders known collectively as amyloidoses. Structural studies of short model peptides are beginning to reveal trends in the types of molecular interactions that drive aggregation and stabilize the packing of beta-sheet layers within fibrillar assemblies. This work investigates the molecular architecture of fibrils formed by the peptide AMed42-49 representing residues 42-49 of the 50 amino acid polypeptide medin associated with aortic medial amyloid, the most common form of senile localized amyloid. The peptide aggregates within 2 days to form bundles of microcrystalline-like needles displaying a high degree of order. Fibrils were prepared from peptides containing up to 23 13C labels, and the solid-state nuclear magnetic resonance (SSNMR) method rotational resonance (RR) was used to determine constraints on the distances between selective atomic sites within fibrils. The constraints are consistent with unbroken beta-strands hydrogen bonded in a parallel in-register arrangement within beta-sheets. Further RR measurements identify close (>6.5 A) contacts between residues F43 and V46 and between S45 and V46, which can only occur between beta-sheet layers and which are consistent with two principal models of beta-sheet arrangements. X-ray fiber diffraction from partially aligned fibrils revealed the classical amyloid diffraction pattern, and comparison of patterns calculated from model coordinates with experimental data allowed determination of a consistent molecular model.

AB - Over 30 polypeptides are known to assemble into highly ordered fibrils associated with pathological disorders known collectively as amyloidoses. Structural studies of short model peptides are beginning to reveal trends in the types of molecular interactions that drive aggregation and stabilize the packing of beta-sheet layers within fibrillar assemblies. This work investigates the molecular architecture of fibrils formed by the peptide AMed42-49 representing residues 42-49 of the 50 amino acid polypeptide medin associated with aortic medial amyloid, the most common form of senile localized amyloid. The peptide aggregates within 2 days to form bundles of microcrystalline-like needles displaying a high degree of order. Fibrils were prepared from peptides containing up to 23 13C labels, and the solid-state nuclear magnetic resonance (SSNMR) method rotational resonance (RR) was used to determine constraints on the distances between selective atomic sites within fibrils. The constraints are consistent with unbroken beta-strands hydrogen bonded in a parallel in-register arrangement within beta-sheets. Further RR measurements identify close (>6.5 A) contacts between residues F43 and V46 and between S45 and V46, which can only occur between beta-sheet layers and which are consistent with two principal models of beta-sheet arrangements. X-ray fiber diffraction from partially aligned fibrils revealed the classical amyloid diffraction pattern, and comparison of patterns calculated from model coordinates with experimental data allowed determination of a consistent molecular model.

KW - Amino Acid Sequence

KW - Amyloid

KW - Antigens, Surface

KW - Carbon Isotopes

KW - Hydrogen Bonding

KW - Magnetic Resonance Spectroscopy

KW - Milk Proteins

KW - Peptide Fragments

KW - Protein Conformation

KW - Protein Structure, Secondary

KW - X-Ray Diffraction

U2 - 10.1021/bi802164e

DO - 10.1021/bi802164e

M3 - Journal article

C2 - 19196164

VL - 48

SP - 3089

EP - 3099

JO - Biochemistry

JF - Biochemistry

SN - 0006-2960

IS - 14

ER -