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Dialysis-related amyloidosis (DRA) involves the aggregation of beta(2)-microglobulin (beta(2)m) into amyloid fibrils. Using Congo red and thioflavin-T binding, electron microscopy, and X-ray fiber diffraction, we have determined conditions under which recombinant monomeric beta(2)m spontaneously associates to form fibrils in vitro. Fibrillogenesis is(More)
Myosin V is a processive actin-based motor protein that takes multiple 36-nm steps to deliver intracellular cargo to its destination. In the laser trap, applied load slows myosin V heavy meromyosin stepping and increases the probability of backsteps. In the presence of 40 mm phosphate (P(i)), both forward and backward steps become less load-dependent. From(More)
Beta(2)-Microglobulin (beta(2)m) is one of over 20 proteins known to be involved in human amyloid disease. Peptides equivalent to each of the seven beta-strands of the native protein, together with an eighth peptide (corresponding to the most stable region in the amyloid precursor conformation formed at pH 3.6, that includes residues in the native strand E(More)
How DNA repair proteins sort through a genome for damage is one of the fundamental unanswered questions in this field. To address this problem, we uniquely labeled bacterial UvrA and UvrB with differently colored quantum dots and visualized how they interacted with DNA individually or together using oblique-angle fluorescence microscopy. UvrA was observed(More)
Human telomeres are maintained by the shelterin protein complex in which TRF1 and TRF2 bind directly to duplex telomeric DNA. How these proteins find telomeric sequences among a genome of billions of base pairs and how they find protein partners to form the shelterin complex remains uncertain. Using single-molecule fluorescence imaging of quantum(More)
Amyloid fibrils formed by incubation of recombinant wild-type human beta(2)-microglobulin (beta(2)M) ab initio in vitro at low pH and high ionic strength are short and highly curved. By contrast, fibrils extracted from patients suffering from haemodialysis-related amyloidosis and those formed by seeding growth of the wild-type protein in vitro with fibrils(More)
The kinetics of spontaneous assembly of amyloid fibrils of wild-type beta(2)-microglobulin (beta(2)M) in vitro, under acid conditions (pH 2.5) and low ionic strength, has been followed using thioflavin-T (ThT) binding. In parallel experiments, the morphology of the different fibrillar species present at different time-points during the growth process were(More)
The ATP hydrolysis rate and shortening velocity of muscle are load-dependent. At the molecular level, myosin generates force and motion by coupling ATP hydrolysis to lever arm rotation. When a laser trap was used to apply load to single heads of expressed smooth muscle myosin (S1), the ADP release kinetics accelerated with an assistive load and slowed with(More)
The ATPase cycle of GroE chaperonins has been examined by transient kinetics to dissect partial reactions in complexes where GroEL is asymmetrically loaded with nucleotides. The occupation of one heptameric ring by ADP does not inhibit the loading of the other with ATP nor does it prevent the consequent structural rearrangement to the "open" state. However,(More)
Myosin Va is a double-headed cargo-carrying molecular motor that moves processively along cellular actin filaments. Long processive runs are achieved through mechanical coordination between the two heads of myosin Va, which keeps their ATPase cycles out of phase, preventing both heads detaching from actin simultaneously. The biochemical kinetics underlying(More)