Circular dichroism studies of the HIV-1 Rev protein and its specific RNA binding site

Biochemistry ◽  
1990 ◽  
Vol 29 (42) ◽  
pp. 9791-9795 ◽  
Author(s):  
Thomas J. Daly ◽  
James R. Rusche ◽  
Theodore E. Maione ◽  
Alan D. Frankel
Keyword(s):  
Circular Dichroism ◽  
Binding Site ◽  
Rna Binding ◽  
Circular Dichroïsm ◽  
Hiv 1 ◽  
Rev Protein

scholarly journals Autoinhibition of the formin Cappuccino in the absence of canonical autoinhibitory domains

2012 ◽  
Vol 23 (19) ◽  
pp. 3801-3813 ◽  
Author(s):  
Batbileg Bor ◽  
Christina L. Vizcarra ◽  
Martin L. Phillips ◽  
Margot E. Quinlan
Keyword(s):  
Circular Dichroism ◽  
Binding Site ◽  
Actin Polymerization ◽  
Intramolecular Interaction ◽  
Hydrodynamic Analysis ◽  
A Site ◽  
Circular Dichroïsm

Formins are a conserved family of proteins known to enhance actin polymerization. Most formins are regulated by an intramolecular interaction. The Drosophila formin, Cappuccino (Capu), was believed to be an exception. Capu does not contain conserved autoinhibitory domains and can be regulated by a second protein, Spire. We report here that Capu is, in fact, autoinhibited. The N-terminal half of Capu (Capu-NT) potently inhibits nucleation and binding to the barbed end of elongating filaments by the C-terminal half of Capu (Capu-CT). Hydrodynamic analysis indicates that Capu-NT is a dimer, similar to the N-termini of other formins. These data, combined with those from circular dichroism, suggest, however, that it is structurally distinct from previously described formin inhibitory domains. Finally, we find that Capu-NT binds to a site within Capu-CT that overlaps with the Spire-binding site, the Capu-tail. We propose models for the interaction between Spire and Capu in light of the fact that Capu can be regulated by autoinhibition.

Small molecules that selectively block RNA binding of HIV-1 rev protein inhibit rev function and viral production

Cell ◽  
1993 ◽  
Vol 74 (6) ◽  
pp. 969-978 ◽  
Author(s):  
Maria L. Zapp ◽  
Seth Stern ◽  
Michael R. Green
Keyword(s):  
Small Molecules ◽  
Rna Binding ◽  
Viral Production ◽  
Hiv 1 ◽  
Rev Protein

scholarly journals Interaction between phloretin and insulin: a spectroscopic study

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Sahri Yanti ◽  
Zhong-Wen Wu ◽  
Dinesh Chandra Agrawal ◽  
Wei-Jyun Chien
Keyword(s):  
Circular Dichroism ◽  
Spectroscopic Study ◽  
Binding Site ◽  
Fluorescence Analysis ◽  
The Body ◽  
Quenching Effect ◽  
Improve Insulin Resistance ◽  
Vis Spectroscopy ◽  
Α Helix ◽  
Circular Dichroïsm

AbstractDiabetes is among the top ten deadly diseases in the world. It occurs either when the pancreas does not produce enough insulin (INS) or when the body cannot effectively use the insulin it produces. Phloretin (PHL) has a biological effect that can treat diabetes. A spectroscopic study was carried out to explore the interaction between phloretin and insulin. UV/Vis spectroscopy, fluorescence spectroscopy, and circular dichroism spectropolarimeter were used in the study. UV/Vis spectra showed that the interaction between PHL and INS produced strong absorption at a wavelength of 282 nm. The fluorescence analysis results showed that the excitation and emission occurred at 280-nm and 305-nm wavelengths, respectively. Temperature changes did not affect INS emissions. However, the interaction of PHL–INS caused a redshift at 305 to 317 nm. Temperature affected the binding constant (Ka) and the binding site (n). Ka decreased with increasing temperature and increased the binding site. The thermodynamic parameters such as enthalpy (ΔH0) and entropy (ΔS0) each had a value of − 16,514 kJ/mol and 22.65 J/mol·K. PHL and INS interaction formed hydrogen bonds and hydrophobic interaction. The free energy (ΔG0) recorded was negative. PHL and INS interactions took place spontaneously. The quenching effect was dynamic and static. KD values were greater than KS. The higher the temperature, the less was KD and KS. The appearance of two negative signals on circular dichroism (CD) spectropolarimeter implies that phloretin could induce regional configuration changes in insulin. The addition of PHL has revealed that the proportion of α-helix in the insulin stabilizes its structure. Phloretin’s stabilization and enhancement of the α-helix structural configuration in insulin indicate that phloretin can improve insulin resistance.

scholarly journals Nuclear Export Signal Masking Regulates HIV-1 Rev Trafficking and Viral RNA Nuclear Export

2016 ◽  
Vol 91 (3) ◽  
Author(s):  
Ryan T. Behrens ◽  
Mounavya Aligeti ◽  
Ginger M. Pocock ◽  
Christina A. Higgins ◽  
Nathan M. Sherer
Keyword(s):  
Gene Expression ◽  
Nuclear Export ◽  
Rna Binding ◽  
Nuclear Export Signal ◽  
Viral Gene Expression ◽  
Viral Gene ◽  
Virion Production ◽  
Export Signal ◽  
Hiv 1 ◽  
Rev Protein

ABSTRACT HIV-1's Rev protein forms a homo-oligomeric adaptor complex linking viral RNAs to the cellular CRM1/Ran-GTP nuclear export machinery through the activity of Rev's prototypical leucine-rich nuclear export signal (NES). In this study, we used a functional fluorescently tagged Rev fusion protein as a platform to study the effects of modulating Rev NES identity, number, position, or strength on Rev subcellular trafficking, viral RNA nuclear export, and infectious virion production. We found that Rev activity was remarkably tolerant of diverse NES sequences, including supraphysiological NES (SNES) peptides that otherwise arrest CRM1 transport complexes at nuclear pores. Rev's ability to tolerate a SNES was both position and multimerization dependent, an observation consistent with a model wherein Rev self-association acts to transiently mask the NES peptide(s), thereby biasing Rev's trafficking into the nucleus. Combined imaging and functional assays also indicated that NES masking underpins Rev's well-known tendency to accumulate at the nucleolus, as well as Rev's capacity to activate optimal levels of late viral gene expression. We propose that Rev multimerization and NES masking regulates Rev's trafficking to and retention within the nucleus even prior to RNA binding. IMPORTANCE HIV-1 infects more than 34 million people worldwide causing >1 million deaths per year. Infectious virion production is activated by the essential viral Rev protein that mediates nuclear export of intron-bearing late-stage viral mRNAs. Rev's shuttling into and out of the nucleus is regulated by the antagonistic activities of both a peptide-encoded N-terminal nuclear localization signal and C-terminal nuclear export signal (NES). How Rev and related viral proteins balance strong import and export activities in order to achieve optimal levels of viral gene expression is incompletely understood. We provide evidence that multimerization provides a mechanism by which Rev transiently masks its NES peptide, thereby biasing its trafficking to and retention within the nucleus. Targeted pharmacological disruption of Rev-Rev interactions should perturb multiple Rev activities, both Rev-RNA binding and Rev's trafficking to the nucleus in the first place.

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