Publication Date:
2008-06-06
Description:
Contemporary phospholipid-based cell membranes are formidable barriers to the uptake of polar and charged molecules ranging from metal ions to complex nutrients. Modern cells therefore require sophisticated protein channels and pumps to mediate the exchange of molecules with their environment. The strong barrier function of membranes has made it difficult to understand the origin of cellular life and has been thought to preclude a heterotrophic lifestyle for primitive cells. Although nucleotides can cross dimyristoyl phosphatidylcholine membranes through defects formed at the gel-to-liquid transition temperature, phospholipid membranes lack the dynamic properties required for membrane growth. Fatty acids and their corresponding alcohols and glycerol monoesters are attractive candidates for the components of protocell membranes because they are simple amphiphiles that form bilayer membrane vesicles that retain encapsulated oligonucleotides and are capable of growth and division. Here we show that such membranes allow the passage of charged molecules such as nucleotides, so that activated nucleotides added to the outside of a model protocell spontaneously cross the membrane and take part in efficient template copying in the protocell interior. The permeability properties of prebiotically plausible membranes suggest that primitive protocells could have acquired complex nutrients from their environment in the absence of any macromolecular transport machinery; that is, they could have been obligate heterotrophs.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2743009/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉 〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2743009/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Mansy, Sheref S -- Schrum, Jason P -- Krishnamurthy, Mathangi -- Tobe, Sylvia -- Treco, Douglas A -- Szostak, Jack W -- F32 GM074506-01/GM/NIGMS NIH HHS/ -- F32 GM07450601/GM/NIGMS NIH HHS/ -- Howard Hughes Medical Institute/ -- England -- Nature. 2008 Jul 3;454(7200):122-5. doi: 10.1038/nature07018. Epub 2008 Jun 4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Howard Hughes Medical Institute, Department of Molecular Biology and the Center for Computational and Integrative Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18528332" target="_blank"〉PubMed〈/a〉
Keywords:
Biological Transport
;
Cell Membrane/chemistry/*metabolism
;
Cell Membrane Permeability/physiology
;
*Cell Physiological Phenomena
;
Fatty Acids/metabolism
;
Heterotrophic Processes
;
*Models, Biological
;
Nucleotides/metabolism
;
Oligonucleotides/*metabolism
;
Ribose/metabolism
;
Templates, Genetic
;
Time Factors
Print ISSN:
0028-0836
Electronic ISSN:
1476-4687
Topics:
Biology
,
Chemistry and Pharmacology
,
Medicine
,
Natural Sciences in General
,
Physics
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