Foldamer hypothesis for the growth and sequence differentiation of prebiotic polymers
Elizaveta Guseva a, b, c, Ronald N. Zuckermann d, and Ken A. Dill a, b, c, 1 ReadCube
Author Affiliations
aLaufer Center for Physical and Quantitative Biology, Stony Brook University, Stony Brook, NY 11794;
bDepartment of Chemistry, Stony Brook University, Stony Brook, NY 11794;
cDepartment of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794;
dMolecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
Contributed by Ken A. Dill, July 10, 2017 (sent for review December 8, 2016; reviewed by Hue Sun Chan and Steve Harvey)
Source/Fonte: PhysOrg
Abstract
Significance
Today’s lifeforms are based on informational polymers, namely proteins and nucleic acids. It is thought that simple chemical processes on the early earth could have polymerized monomer units into short random sequences. It is not clear, however, what physical process could have led to the next level—to longer chains having particular sequences that could increase their own concentrations. We study polymers of hydrophobic and polar monomers, such as today’s proteins. We find that even some random sequence short chains can collapse into compact structures in water, with hydrophobic surfaces that can act as primitive catalysts, and that these could elongate other chains. This mechanism explains how random chemical polymerizations could have given rise to longer sequence-dependent protein-like catalytic polymers.
Abstract
It is not known how life originated. It is thought that prebiotic processes were able to synthesize short random polymers. However, then, how do short-chain molecules spontaneously grow longer? Also, how would random chains grow more informational and become autocatalytic (i.e., increasing their own concentrations)? We study the folding and binding of random sequences of hydrophobic (HH) and polar (PP) monomers in a computational model. We find that even short hydrophobic polar (HP) chains can collapse into relatively compact structures, exposing hydrophobic surfaces. In this way, they act as primitive versions of today’s protein catalysts, elongating other such HP polymers as ribosomes would now do. Such foldamer catalysts are shown to form an autocatalytic set, through which short chains grow into longer chains that have particular sequences. An attractive feature of this model is that it does not overconverge to a single solution; it gives ensembles that could further evolve under selection. This mechanism describes how specific sequences and conformations could contribute to the chemistry-to-biology (CTB) transition.
origin of life HP model biopolymers autocatalytic sets
Footnotes
1To whom correspondence should be addressed. Email: dill@laufercenter.org.
Author contributions: R.N.Z. and K.A.D. designed research; E.G. performed research; E.G. and R.N.Z. analyzed data; and E.G. and K.A.D. wrote the paper.
Reviewers: H.S.C., University of Toronto; and S.H., University of Pennsylvania.
The authors declare no conflict of interest.
This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1620179114/-/DCSupplemental.
Freely available online through the PNAS open access option.
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