Orb2 is a functional amyloid that plays a key role in Drosophila long-term memory formation. Orb2 has two isoforms that differ in their N-termini. The N-terminus of the A isoform (Orb2A) that precedes its Q-rich prion-like domain has been shown to be important for Orb2 aggregation and long-term memory. However, besides the fact that it forms fibrillar aggregates, structural information of Orb2 is largely absent. To understand the importance of the N-terminus of Orb2A and its relation to the fibril core, we recorded solid-state NMR and EPR data on fibrils formed by the first 88 residues of Orb2A (Orb2A88). These data show that the N-terminus of Orb2A not only promotes the formation of fibrils, but also forms the fibril core of Orb2A88. This fibril core has an in-register parallel β-sheet structure and does not include the Q-rich, prion-like domain of Orb2. The Q-rich domain is part of the unstructured region, which becomes increasingly dynamic towards the C-terminus.

Objective: We report results of a community-based multisite, randomized controlled trial of Nuevo Amanecer (NA-II), a 10-week stress management program for rural, low literacy Latina breast cancer survivors. Methods: Trained peers delivered NA-II to Spanish-speaking Latinas with nonmetastatic breast cancer in three rural communities. Women were randomized to receive the program immediately or wait 6 months. Assessments were conducted at baseline, 3 months, and 6 months. Primary outcomes were breast cancer-specific quality of life domains; secondary outcomes included general distress symptoms and stress management skills. Intention-to-treat analyses using repeated-measures linear regression models estimated changes in slope between groups. Results: Of 153 participants (76 randomized to intervention, 77 to control group), 92% were retained at 6 months. Mean age was 54.8 years (SD = 10.5); 80% had less than high school education. There were no statistically significant treatment × time effects on quality of life. Compared to women in the control group, intervention group women reported greater improvements in anxiety at 6 months (−0.20 vs −0.02, P = .049; range 0-4) as well as three stress management skills: relaxation at 3 months (+0.98 vs −0.07, P < .0001; range 0-4) and 6 months (+0.82 vs +0.04, P < .001), awareness of tension at 3 months (+0.31 vs −0.19, P < .01; range 0-4) and 6 months (+0.29 vs −0.11, P < .05), and coping confidence at 3 months (+0.12 vs −0.23, P < .01; range 0-4). Conclusions: Stress management programs delivered by trained peers in rural community settings can reduce anxiety and improve stress management skills among Latina breast cancer survivors. Trial registration: http://www.ClinicalTrials.gov identifier NCT02931552.

Intrinsically disordered protein domains are not only found in soluble proteins but can also be part of large protein complexes or protein aggregates. For example, several amyloid fibrils have intrinsically disordered domains framing a rigid β-sheet rich core. These disordered domains can often be observed using solution NMR methods in combination with modest magic angle spinning and without perdeuteration. But how can these regions be detected using solution NMR methods when they are part of a fibril that is not tumbling isotropically in solution? Here we addressed this question by investigating the dynamic C-terminus of huntingtin exon-1 (HTTex1) fibrils that are important in Huntington’s Disease. We assigned the most dynamic regions of the C-terminus of three HTTex1 variants. Based on this assignment, we measured site-specific residual chemical shifts, peak intensities, and R1, R′2 and R1ρ 15N relaxation rates. In addition, we determined the residual 1H-15N dipolar couplings of this region. Our results show that the dipolar couplings are averaged to a very high degree resulting in an order parameter that is essentially zero. Together, our data show that the C-terminus of HTTex1 is intrinsically disordered and undergoes motions in the high picosecond to low nanosecond range.

Lipid membranes interact with and influence the aggregation of many amyloid-forming proteins. Orb2 is a cytoplasmic polyadenylation element-binding protein homolog in Drosophila melanogaster that forms functional amyloids necessary for long-term memory. One isoform, Orb2A, has a unique N-terminus that has been shown to be important for the formation of amyloid-like aggregates and long-term memory in vivo. Orb2A is also found enriched in the synaptic membrane fraction. Our sequence and hydropathy analysis suggests that it can form an amphipathic helix, which is ideal for lipid membrane interaction. We used circular dichroism and site-directed spin labeling coupled with electron paramagnetic resonance to test the first 88 amino acids of Orb2A for lipid interaction. We show that Orb2A1-88 interacts with anionic lipid membranes using an amphipathic helix at its unique N-terminus. This interaction depends on the charge of the lipid membrane and the degree of membrane curvature. We used transmission electron microscopy and electron paramagnetic resonance to show that the presence of anionic small unilamellar vesicles inhibits amyloid fibril formation by Orb2A. This inhibition by anionic membranes could be a potential mechanism regulating Orb2A amyloid formation in vivo.

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