Kinetic Intermediates of ?(2)-Microglobulin Fibril Elongation Probed by Pulse-Labelin

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Kinetic Intermediates of ?(2)-Microglobulin Fibril Elongation Probed by Pulse-Labeling H/D Exchange Combined with NMR Analysis.

Related Articles Kinetic Intermediates of ?(2)-Microglobulin Fibril Elongation Probed by Pulse-Labeling H/D Exchange Combined with NMR Analysis.

J Mol Biol. 2010 Nov 22;

Authors: Konuma T, Chatani E, Yagi M, Sakurai K, Ikegami T, Naiki H, Goto Y

Amyloid fibril elongation of denatured proteins is considered to involve cycles of coupled binding and misfolding. To gain insights into the possible kinetic intermediate(s), we performed hydrogen/deuterium (H/D) exchange of amide protons during fibril elongation with ?(2)-microglobulin (?2-m) at pD 2.5, under which conditions ?2-m is acid-denatured. To study the conformational change of the monomeric ?2-m monitored by NMR spectroscopy, (15)N-labeled monomers and non-labeled seeds were used. Pulse-labeling H/D exchange with a quenched-flow apparatus indicated the rate-limiting intermediate at pD 2.5 not to be protected from the exchange, even disrupting a hydrophobic cluster present in the acid-denatured ?2-m. Significant protection was acquired upon the transition to the fibrils. Considering the suggestion that the rate-limiting intermediates are bound to the lateral surface of seed fibrils, weak interactions with a largely unfolded conformation might be useful for their dynamic sliding to the growing ends. The results support a new model of fibril elongation with intermediates bound to the lateral surface of seeds.

PMID: 21108949 [PubMed - as supplied by publisher]



Source: PubMed