Conformations within soluble oligomers and insoluble aggregates revealed by resonance energy transferBiopolymers
AbstractA fluorescently labeled 20-residue polyglutamic acid (polyE) peptide 20 amino acid length polyglutamic acid (E(20)) was used to study structural changes which occur in E(20) as it co-aggregates with other unlabeled polyE peptides. Resonance energy transfer (RET) was performed using an o-aminobenzamide donor at the N-terminus and 3-nitrotyrosine acceptor at the C-terminus of E(20). PolyE aggregates were not defined as amyloid, as they were nonfibrillar and did not bind congo red. Circular dichroism measurements indicate that polyE aggregation involves a transition from alpha-helical monomers to aggregated beta-sheets. Soluble oligomers are also produced along with aggregates in the reaction, as determined through size exclusion chromatography. Time-resolved and steady-state RET measurements reveal four dominant E(20) conformations: (1) a partially collapsed conformation (24 A donor-acceptor distance) in monomers, (2) an extended conformation in soluble oligomers (>29 A donor-acceptor distance), (3) a minor partially collapsed conformation (22 A donor-acceptor distance) in aggregates, and (4) a major highly collapsed conformation (13 A donor-acceptor distance) in aggregates. These findings demonstrate the use of RET as a means of determining angstrom-level structural details of soluble oligomer and aggregated states of proteins.
Citation InformationJyothi L. Digambaranath, Loan Dang, Monika Dembinska, Andrew Vasyluk, et al.. "Conformations within soluble oligomers and insoluble aggregates revealed by resonance energy transfer" Biopolymers Vol. 93 Iss. 4 (2010) p. 299 - 317
Available at: http://works.bepress.com/john_finke/17/