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Membrane Transport Processes Analyzed by a Highly Parallel Nanopore Chip System at Single Protein Resolution
Published on: August 16, 2016
Permeation of nucleosides through lipid bilayers
1NASA Ames Research Center, Mail Stop 229-1, Moffett Field, California 94035, USA. Chenyu.Wei@nasa.gov
The Journal of Physical Chemistry. B
|March 17, 2011
Summary
Primordial cell membranes favored ribose sugar uptake over nucleosides. This selective uptake mechanism for sugars, not nucleosides, was crucial for early RNA formation and the origins of life.
Area of Science:
- Biochemistry
- Origin of Life Research
- Computational Biophysics
Background:
- Understanding the origins of life requires elucidating how early information polymers, like RNA, synthesized.
- Membrane diastereoselectivity favoring ribose uptake may have promoted its incorporation into nucleic acids.
- Previous research showed membranes preferentially incorporate ribose over its diastereomers.
Purpose of the Study:
- To investigate if similar membrane diastereoselectivity favored nucleoside uptake compared to sugars.
- To determine the energetic barriers and permeability coefficients for nucleoside permeation through lipid bilayers.
- To assess the implications for primordial RNA synthesis and nutrient uptake in early cells.
Main Methods:
- Molecular dynamics simulations were employed to model nucleoside permeation through a 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine lipid bilayer.
- Free energy barriers and permeability coefficients for ribo-adenosine and arabino-adenosine were calculated.
- The conformational states of nucleosides within the membrane were analyzed.
Main Results:
- Free energy barriers for ribo-adenosine (10.0 kcal/mol) and arabino-adenosine (10.4 kcal/mol) permeation were similar.
- Permeability coefficients for ribo-adenosine (9.1 × 10⁻⁷ cm/s) and arabino-adenosine (5.3 × 10⁻⁷ cm/s) were also comparable.
- Unlike ribose, nucleosides exist in the furanose form, preventing the formation of stabilizing intramolecular interactions within the membrane.
Conclusions:
- The diastereoselectivity favoring ribose uptake is not preserved for nucleosides.
- The furanose form of nucleosides eliminates the stabilizing interactions observed for ribose, leading to similar permeation barriers.
- Selective nutrient uptake favored primordial RNA synthesis only when sugars, not nucleosides, were absorbed by early cell membranes.
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