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Abstract Recent advances in fluorogen-binding “light-up” RNA aptamers have enabled protein-free detection of RNA in cells. Detailed biophysical characterization of folding of G-Quadruplex (GQ)-based light-up aptamers such as Spinach, Mango and Corn is still lacking despite the potential implications on their folding and function. In this work we employ single-molecule fluorescence-force spectroscopy to examine mechanical responses of Spinach2,iMangoIII and MangoIV. Spinach2 unfolds in four discrete steps as force is increased to 7 pN and refolds in reciprocal steps upon force relaxation. In contrast, GQ-core unfolding iniMangoIII and MangoIV occurs in one discrete step at forces >10 pN and refolding occurred at lower forces showing hysteresis. Co-transcriptional folding using superhelicases shows reduced misfolding propensity and allowed a folding pathway different from refolding. Under physiologically relevant pico-Newton levels of force, these aptamers may unfold in vivo and subsequently misfold. Understanding of the dynamics of RNA aptamers will aid engineering of improved fluorogenic modules for cellular applications.
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Does protein unfolding play a functional role in vivo ?
Unfolding and refolding of multidomain proteins under force have yet to be recognized as a major mechanism of function for proteinsin vivo. In this review, we discuss the inherent properties of multidomain proteins under a force vector from a structural and functional perspective. We then characterize three main systems where multidomain proteins could play major roles through mechanical unfolding: muscular contraction, cellular mechanotransduction, and bacterial adhesion. We analyze how key multidomain proteins for each system can produce a gain‐of‐function from the perspective of a fine‐tuned quantized response, a molecular battery, delivery of mechanical work through refolding, elasticity tuning, protection and exposure of cryptic sites, and binding‐induced mechanical changes. Understanding how mechanical unfolding and refolding affect function will have important implications in designing mechano‐active drugs against conditions such as muscular dystrophy, cancer, or novel antibiotics.
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- PAR ID:
- 10452988
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- The FEBS Journal
- Volume:
- 288
- Issue:
- 6
- ISSN:
- 1742-464X
- Page Range / eLocation ID:
- p. 1742-1758
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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