Single-molecule folding.

Xiaowei Zhuang; Matthias Rief

doi:10.1016/s0959-440x(03)00011-3

Home/Archive/PubMed

PubMed · 12581665

Single-molecule folding.

Xiaowei Zhuang·Matthias Rief

View original source ↗Export metadata ↓

Abstract

Recent developments in fluorescence and force spectroscopy enable us to go beyond the ensemble average and measure the behavior of individual biomacromolecules. These single-molecule approaches can directly resolve transient intermediate states and multiple reaction pathways, and thus are uniquely powerful in characterizing the complex dynamics of biological processes. Recent applications of these two techniques to the protein and RNA folding problems have led to exciting new results.

Explore related subjects

Connectin Fluorescence Resonance Energy Transfer Macromolecular Substances Microscopy, Atomic Force Models, Molecular Motion Muscle Proteins Nucleic Acid Conformation Physical Stimulation Protein Conformation Protein Denaturation Protein Folding Protein Kinases Proteins RNA Journal Article Review

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

Xiaowei Zhuang, Matthias Rief. 2003. Single-molecule folding.. https://doi.org/10.1016/s0959-440x(03)00011-3

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2006

MDM2 interacts with and downregulates a sarcomeric protein, TCAP.

Recent reports have shown that MDM2 may attenuate hypertrophy of cardiac myocytes. However, mechanism of MDM2 involving in this process is unclear. In this study, we identified a novel specific MDM2-binding protein TCAP by the yeast two-hybrid screen. It was validated by GST pull-down and co-immunoprecipitation assays. Confocal analysis showed that MDM2 and TCAP co-localized in the nucleus, and elevated MDM2 expression could alter the subcellular localization of TCAP. Notably, MDM2 downregulated the protein level of TCAP through the proteasomal pathway, and this downregulation was inhibited by p14(ARF). In addition, our results suggested that the degradation of TCAP by MDM2 was through the ubiquitin-independent pathway. Given that TCAP is a key component involving in the cardiac hypertrophy, the degradation of TCAP by MDM2 might be connected with the roles of MDM2 in cardiac hypertrophy. Further investigation will focus on the biological significance of MDM2-TCAP interaction in cardiac hypertrophy.

Connectin↗

PubMed2006

Force-dependent chemical kinetics of disulfide bond reduction observed with single-molecule techniques.

The mechanism by which mechanical force regulates the kinetics of a chemical reaction is unknown. Here, we use single-molecule force-clamp spectroscopy and protein engineering to study the effect of force on the kinetics of thiol/disulfide exchange. Reduction of disulfide bonds through the thiol/disulfide exchange chemical reaction is crucial in regulating protein function and is known to occur in mechanically stressed proteins. We apply a constant stretching force to single engineered disulfide bonds and measure their rate of reduction by DTT. Although the reduction rate is linearly dependent on the concentration of DTT, it is exponentially dependent on the applied force, increasing 10-fold over a 300-pN range. This result predicts that the disulfide bond lengthens by 0.34 A at the transition state of the thiol/disulfide exchange reaction. Our work at the single bond level directly demonstrates that thiol/disulfide exchange in proteins is a force-dependent chemical reaction. Our findings suggest that mechanical force plays a role in disulfide reduction in vivo, a property that has never been explored by traditional biochemistry. Furthermore, our work also indicates that the kinetics of any chemical reaction that results in bond lengthening will be force-dependent.

Connectin↗

PubMed2006

The Ig doublet Z1Z2: a model system for the hybrid analysis of conformational dynamics in Ig tandems from titin.

Titin is a gigantic elastic filament that determines sarcomere ultrastructure and stretch response in vertebrate muscle. It folds into numerous Ig and FnIII domains connected in tandem. Data on interdomain arrangements and dynamics are essential for understanding the function of this filament. Here, we report a mechanistic analysis of the conformational dynamics of two Ig domains from the N terminus of titin, Z1Z2, by using X-ray crystallography, SAXS, NMR relaxation data, and residual dipolar couplings in combination. Z1Z2 preferentially adopts semiextended conformations in solution, with close-hinge arrangements representing low-probability states. Although interdomain contacts are not observed, the linker appears to acquire moderate rigidity via small, local hydrophobic interactions. Thus, Z1Z2 constitutes an adaptable modular system with restricted dynamics. We speculate that its preexistent conformation contributes to the selective recruitment of the binding partner telethonin onto the repetitive surface of the filament. The structural interconversion of four Z1Z2 conformers is analyzed.

Connectin↗