HIV Rev self-assembly is linked to a molten-globule to compact structural transition

Rajendran Surendran, Petr Herman, Zhijie Cheng, Thomas J. Daly, James Lee

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

By regulating the differential expression of proviral pre mRNA in the host cell, Rev plays a crucial role in the HIV-1 life cycle. The capacity of Rev to function is intimately linked to its ability to self-associate. Nevertheless, little is known about the exact role of self-association in the molecular mechanism defining its biological activity. A prerequisite knowledge is a definition of the molecular events undertaken by Rev during the process of self-assembly. Thus, this study was initiated to monitor the structure of Rev as a function of protein concentration. Rev undergoes a structural transition as a consequence of self-assembly. This structural transition was monitored by three spectroscopic methods. The accessibility of the single tryptophan in Rev monomer to acrylamide quenching increases with decreasing protein concentration. At very low concentration of Rev, the tryptophan accessibility is close to that of an unfolded Rev. As evaluated by circular dichroism, the secondary structure of Rev is protein concentration dependent as evidenced by an increase in the magnitude of ellipticity with increasing protein concentration. Further, results from ANS binding studies indicate that the ANS binding sites in Rev experience an apparent increase in hydrophobicity as the Rev concentration was increased. These concentration dependent changes seem to reach a maximum above 5 μM Rev monomer concentration. In order to define the mode of Rev self-association sedimentation velocity and equilibrium experiments were conducted. There are evidently two consecutive progressive association processes. At protein concentrations below 0.5 mg/ml, the data from sedimentation studies can be fitted to a single isodesmic model. Simulation of velocity sedimentation profile indicates that free Rev monomer that has not entered into the association processes can best be described to exhibit a value of S20,w that is substantially smaller than 1.4 S, a value needed to fit the rest of the data. The latter value is consistent for a Rev monomer with the expected molecules weight and if it were to assume a compact globular shape. These spectroscopic and hydrodynamic results imply that monomeric Rev is in a molten globule state, which becomes more compact upon self-association.

Original languageEnglish (US)
Pages (from-to)101-119
Number of pages19
JournalBiophysical Chemistry
Volume108
Issue number1-3
DOIs
StatePublished - Mar 1 2004

Fingerprint

human immunodeficiency virus
globules
Self assembly
Molten materials
self assembly
HIV
Monomers
Sedimentation
Association reactions
Tryptophan
proteins
Proteins
monomers
rev Gene Products
Astronomical Netherlands Satellite
Acrylamide
tryptophan
RNA Precursors
Hydrodynamics
Circular Dichroism

Keywords

  • HIV-1
  • Rev
  • Self-association

ASJC Scopus subject areas

  • Biochemistry
  • Physical and Theoretical Chemistry
  • Biophysics

Cite this

HIV Rev self-assembly is linked to a molten-globule to compact structural transition. / Surendran, Rajendran; Herman, Petr; Cheng, Zhijie; Daly, Thomas J.; Lee, James.

In: Biophysical Chemistry, Vol. 108, No. 1-3, 01.03.2004, p. 101-119.

Research output: Contribution to journalArticle

Surendran, Rajendran ; Herman, Petr ; Cheng, Zhijie ; Daly, Thomas J. ; Lee, James. / HIV Rev self-assembly is linked to a molten-globule to compact structural transition. In: Biophysical Chemistry. 2004 ; Vol. 108, No. 1-3. pp. 101-119.
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abstract = "By regulating the differential expression of proviral pre mRNA in the host cell, Rev plays a crucial role in the HIV-1 life cycle. The capacity of Rev to function is intimately linked to its ability to self-associate. Nevertheless, little is known about the exact role of self-association in the molecular mechanism defining its biological activity. A prerequisite knowledge is a definition of the molecular events undertaken by Rev during the process of self-assembly. Thus, this study was initiated to monitor the structure of Rev as a function of protein concentration. Rev undergoes a structural transition as a consequence of self-assembly. This structural transition was monitored by three spectroscopic methods. The accessibility of the single tryptophan in Rev monomer to acrylamide quenching increases with decreasing protein concentration. At very low concentration of Rev, the tryptophan accessibility is close to that of an unfolded Rev. As evaluated by circular dichroism, the secondary structure of Rev is protein concentration dependent as evidenced by an increase in the magnitude of ellipticity with increasing protein concentration. Further, results from ANS binding studies indicate that the ANS binding sites in Rev experience an apparent increase in hydrophobicity as the Rev concentration was increased. These concentration dependent changes seem to reach a maximum above 5 μM Rev monomer concentration. In order to define the mode of Rev self-association sedimentation velocity and equilibrium experiments were conducted. There are evidently two consecutive progressive association processes. At protein concentrations below 0.5 mg/ml, the data from sedimentation studies can be fitted to a single isodesmic model. Simulation of velocity sedimentation profile indicates that free Rev monomer that has not entered into the association processes can best be described to exhibit a value of S20,w that is substantially smaller than 1.4 S, a value needed to fit the rest of the data. The latter value is consistent for a Rev monomer with the expected molecules weight and if it were to assume a compact globular shape. These spectroscopic and hydrodynamic results imply that monomeric Rev is in a molten globule state, which becomes more compact upon self-association.",
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