From Self-Assembled Vesicles to Protocells

Chen, Irene; Walde, Peter

doi:10.1101/cshperspect.a002170

Cited by 234 publications

(198 citation statements)

References 89 publications

(88 reference statements)

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“…Thus, life's abiotic origin is not just a chicken-and-egg problem, but also a yolk-and-shell problem. Besides the RNA-world, there is in fact a lipid-world theory that argues for the early appearance of vesicles and protocells (90,91). Venter and coworkers' Mycoplasma laboratorium experiment (92) or Michael Crichton's Jurassic Park fiction both require placing remodeled or renewed DNAs into a preexisting cell.…”

Section: The Originmentioning

confidence: 99%

Feeling the hidden mechanical forces in lipid bilayer is an original sense

Anishkin

Loukin²,

Teng³

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

246

216

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Life's origin entails enclosing a compartment to hoard material, energy, and information. The envelope necessarily comprises amphipaths, such as prebiotic fatty acids, to partition the two aqueous domains. The self-assembled lipid bilayer comes with a set of properties including its strong anisotropic internal forces that are chemically or physically malleable. Added bilayer stretch can alter force vectors on embedded proteins to effect conformational change. The force-from-lipid principle was demonstrated 25 y ago when stretches opened purified Escherichia coli MscL channels reconstituted into artificial bilayers. This reductionistic exercise has rigorously been recapitulated recently with two vertebrate mechanosensitive K + channels (TREK1 and TRAAK). Membrane stretches have also been known to activate various voltage-, ligand-, or Ca 2+ -gated channels. Careful analyses showed that Kv, the canonical voltage-gated channel, is in fact exquisitely sensitive even to very small tension. In an unexpected context, the canonical transient-receptor-potential channels in the Drosophila eye, long presumed to open by ligand binding, is apparently opened by membrane force due to PIP 2 hydrolysis-induced changes in bilayer strain. Being the intimate medium, lipids govern membrane proteins by physics as well as chemistry. This principle should not be a surprise because it parallels water's paramount role in the structure and function of soluble proteins. Today, overt or covert mechanical forces govern cell biological processes and produce sensations. At the genesis, a bilayer's response to osmotic force is likely among the first senses to deal with the capricious primordial sea. mechanosensitivity | force sensing | channel gating | bilayer mechanics | touch

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Section: The Originmentioning

confidence: 99%

Feeling the hidden mechanical forces in lipid bilayer is an original sense

Anishkin

Loukin²,

Teng³

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

246

216

View full text Add to dashboard Cite

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“…The first membranes were most probably singlechain fatty acids 143,[145][146][147][148] . Once simple amphiphilic molecules were present, spontaneous formation of vesicles became possible under specific circumstances 145,147,149 . Interestingly, spontaneous membrane assembly is also catalysed by certain mineral surfaces 150 , offering a conceptual bridge between the surface bound and encapsulated replicators in the evolution of the RNA world.…”

Section: Ii/3 Active Compartmentalizationmentioning

confidence: 99%

The dynamics of the RNA world: insights and challenges

Kun

Szilágyi

Könnyű

et al. 2015

Annals of the New York Academy of Sciences

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The problem of the origin of life is not only one of structure but also that of dynamics. Ever since the seminal result of Manfred Eigen in 1971 showing that early template replication suffers from an error threshold, research has tackled the issue of how early genomes could have been dynamically stable without highly evolved mechanisms such as accurate replication and chromosomes. We review the theory of the origin, maintenance and enhancement of the RNA world as an evolving population of dynamical systems. Investigation of sequence space has revealed how structures are allocated in sequence space and how this affects the nature of the error threshold that sets the selectively maintainable genome length. New applications of old dynamical theory are still possible: the application of Gause's principle of competitive exclusion, based on resource utilisation, to RNA replication predicts that at most four pairs (plus and minus strands) can stably be maintained on four nucleotides. Other mechanisms of early template coexistence should be regarded as additional means to raise the number of coexisting species above the number set by the competitive exclusion principle. One such example is the hypercycle in which templates were postulated to help replication of the next member in a cycle superimposed on individual replication cycles. Although the hypercycle is ecologically unstable it is evolutionarily unstable because it cannot efficiently compete against emerging parasites. Population structure can modify this conclusion but not without further qualification. The simplest form of population structure is limited diffusion on a surface. This simple mechanism can ensure the coexistence of competing ribozymes contributing to surface metabolism as well as the spread of efficient replicases despite the parasite problem. Hypercyclescan only be saved by active compartmentalization when replicators are enclosed in reproducing protocells. Once there are protocells there is no need for internal hypercyclic organization, however. Finally we review two crucial adaptations that enhanced the RNA world: chromosomes and enzymatic metabolism. Interestingly, it was shown that these two have been presumably coevolutionarily linked because protocells harbouring unlinked, competing ribozymes are better off if the ribozymes remain inefficient but generalists. The appearance of chromosomes alleviates intragenomic conflict and is enabling constraint for the emergence of specific and efficient enzymes.The possibility of an RNA world, a period in the origin of life on Earth, when RNA molecules acted both as enzymes and as genetic material, was suggested well before the name was coined by Gilbert in 1986 1 . The history of the research on the origin of life 2 tells us that the potential prebiotic importance of RNA was suggested as early as in the late 50's. When it became established that living cells harbour much more RNA than DNA some biologist have proposed that RNA preceded DNA during evolution 3,4 . The discovery of the details of protein ...

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“…Moreover, there are RNA molecules that catalyse amphiphiles formation. Laboratory experiments confirmed that amphiphilic membranes can self-assembly spontaneously in prebiotic environments (Chen and Walde, 2010). Minerals and specific ions that existed on the primordial Earth can speed up the process of formation of membranes.…”

Section: 2mentioning

confidence: 89%

Mathematical modelling of molecule evolution in protocells

Myszor

Cyran

2013

International Journal of Applied Mathematics and Computer Science

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In this article, we analyse the process of the emergence of RNA polynucleotides located in an enclosed environment, at an early stage of the RNA world. Therefore we prepared a mathematical model, composed of a set of differential equations, which simulates the behaviour of an early biological system bounded by a protocell membrane. There is evidence that enclosed environments were available on the primordial Earth. There are also experimental proofs that RNA strands can develop in these formations. The proposed model allows analysis of the influence of membrane permeability on the composition of internal material. It takes into account phenomena that lead to the elongation of an RNA strand (ligation), fission of molecules (phosphodiester bond breakage) and replication of polynucleotides. Results obtained from the model point out that the existence of protocells might support concentration of material and creation of longer molecules.

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From Self-Assembled Vesicles to Protocells

Cited by 234 publications

References 89 publications

Feeling the hidden mechanical forces in lipid bilayer is an original sense

Feeling the hidden mechanical forces in lipid bilayer is an original sense

The dynamics of the RNA world: insights and challenges

Mathematical modelling of molecule evolution in protocells

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