Penetration of HIV-1 Tat47-57 into PC/PE Bilayers Assessed by MD Simulation and X-ray Scattering.

Chris Neale,Angel García,Stephanie Tristram-Nagle,Kun Huang

doi:10.3390/membranes5030473

Chris Neale, Angel García + Show 2 more

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https://doi.org/10.3390/membranes5030473

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Abstract

The interactions of the basic, cell-penetrating region (Y47GRKKRRQRRR57) of the HIV-1 Tat protein with dioleoylphosphatidylcholine (DOPC) bilayers were previously assessed by comparing experimental X-ray diffuse scattering with atomistic molecular dynamics simulations. Here, we extend this investigation by evaluating the influence of phosphatidylethanolamine (PE) lipids. Using experimental bilayer form factors derivedfrom X-ray diffuse scattering data as a guide, our simulations indicate that Tat peptides localize close to the carbonyl-glycerol group in the headgroup region of bilayers composed of either DOPC or DOPC:DOPE (1:1) lipid. Our results also suggest that Tat peptides may more frequently insert into the hydrophobic core of bilayers composed of PC:PE (1:1) lipids than into bilayers composed entirely of PC lipids. PE lipids may facilitate peptide translocation across a lipid bilayer by stabilizing intermediate states in which hydrated peptides span the bilayer.

Highlights

The HIV-1 viral genome encodes a protein called Tat that enhances viral transcription [1].A peptide derived from this protein (Y47GRKKRRQRRR57), hereafter referred to as Tat47–57, is capable of penetrating cell membranes [2]
Mishra et al reported that rhodamine-tagged Tat47–57 enters giant unilamellar vesicles (GUVs) composed of PS/PC (1:4 mole ratio) immeasurably slowly, but crosses a GUV composed of PS/PC/PE (1:2:1) lipids within 30 s [11]
molecular dynamics (MD) simulation in which Tat47–57 was restrained in various regions of the bilayer

Summary

Introduction

The HIV-1 viral genome encodes a protein called Tat that enhances viral transcription [1].A peptide derived from this protein (Y47GRKKRRQRRR57), hereafter referred to as Tat, is capable of penetrating cell membranes [2]. Many cell penetrating peptides (CPPs), including those derived from Tat, are capable of carrying cargo into live cells [3,4] It is controversial, if endocytosis is involved, which would require ATP [5,6,7,8,9,10]. Mishra et al reported that rhodamine-tagged Tat enters giant unilamellar vesicles (GUVs) composed of PS/PC (1:4 mole ratio) immeasurably slowly, but crosses a GUV composed of PS/PC/PE (1:2:1) lipids within 30 s [11] In another experiment, fluorescently labeled Tat did not enter GUVs containing only PC with 20 mole % cholesterol, but translocated rapidly when PS or PE was included with PC [12].

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