Elisa Biondi's Publications
Artificially Expanded Genetic Information Systems
for New Aptamer Technologies
Elisa Biondi and Steven A. Benner
, MDPI (2018) 6, 53; doi:10.3390/biomedicines6020053
Directed evolution was first applied to diverse libraries of DNA and RNA molecules a
quarter century ago in the hope of gaining technology that would allow the creation of receptors,
ligands, and catalysts on demand. Despite isolated successes, the outputs of this technology have been
somewhat disappointing, perhaps because the four building blocks of standard DNA and RNA have
too little functionality to have versatile binding properties, and offer too little information density
to fold unambiguously. This review covers the recent literature that seeks to create an improved
platform to support laboratory Darwinism, one based on an artificially expanded genetic information
system (AEGIS) that adds independently replicating nucleotide "letters" to the evolving "alphabet".
Mineral-Organic Interactions in Prebiotic
Steven A. Benner, Hyo-Joong Kim, and Elisa Biondi
Nucl. Acids & Mol. Bio.
35 , ed. Katsuhiko S. Murakami, Michael A. Trakselis , Springer 31-83 (2018) https://doi.org/10.1007/978-3-319-93584-3_3
A common criticism of "prebiotic chemistry research" is that it is done
with starting materials that are too pure, in experiments that are too directed, to get
results that are too scripted, under conditions that could never have existed on Earth.
Planetary scientists in particular remark that these experiments often arise simply
because a chemist has a "cool idea" and then pursues it without considering external
factors, especially geological and planetary context. A growing literature addresses
this criticism and is reviewed here. We assume a model where RNA emerged
spontaneously from a prebiotic environment on early Earth, giving the planet its
first access to Darwinism. This "RNA First Hypothesis" is not driven by the intrinsic
prebiotic accessibility; quite the contrary, RNA is a "prebiotic chemist's nightmare."
However, by assuming models for the accretion of the Earth, the formation of the
Moon, and the acquisition of Earth's "late veneer," a reasonable geological model
can be envisioned to deliver the organic precursors needed to form the nucleobases
and ribose of RNA. A geological model having an environment with dry arid land
under a carbon dioxide atmosphere receiving effluent from serpentinizing igneous
rocks allows their conversion to nucleosides and nucleoside phosphates. Mineral
elements including boron and molybdenum prevent organic material from devolving
to form "tars" along the way. And dehydration and activation allows the formation of
oligomeric RNA that can be stabilized by adsorption on available minerals.
Adsorption of RNA on mineral surfaces and mineral precipitates
Elisa Biondi, Yoshihiro Furukawa, Jun Kawai, and Steven A. Benner
Beilstein J. Org. Chem.
, Beilstein Institute (2017) 13, 393-404
The prebiotic significance of laboratory experiments that study the interactions between oligomeric RNA and mineral species is difficult to know. Natural exemplars of specific minerals can differ widely depending on their provenance. While laboratory-generated samples of synthetic minerals can have controlled compositions, they are often viewed as "unnatural". Here, we show how trends in the interaction of RNA with natural mineral specimens, synthetic mineral specimens, and co-precipitated pairs of synthetic minerals, can make a persuasive case that the observed interactions reflect the composition of the minerals themselves, rather than their being simply examples of large molecules associating nonspecifically with large surfaces. Using this approach, we have discovered Periodic Table trends in the binding of oligomeric RNA to alkaline earth carbonate minerals and alkaline earth sulfate minerals, where those trends are the same when measured in natural and synthetic minerals. They are also validated by comparison of co-precipitated synthetic minerals. We also show differential binding of RNA to polymorphic forms of calcium carbonate, and the stabilization of bound RNA on aragonite. These have relevance to the prebiotic stabilization of RNA, where such carbonate minerals are expected to have been abundant, as they appear to be today on Mars.
Laboratory evolution of artificially expanded DNA gives redesignable aptamers that target the toxic form of anthrax protective antigen
Biondi E, Lane JD, Das D, Dasgupta S, Piccirilli JA, Hoshika S, Bradley KM, Krantz BA, Benner SA
Nucl. Acids Res.
(2016) Oct 3. pii: gkw890. PubMed PMID: 27701076
Reported here is a laboratory in vitro evolution (LIVE)
experiment based on an artificially expanded genetic
information system (AEGIS). This experiment delivers
the first example of an AEGIS aptamer that binds
to an isolated protein target, the first whose structural
contact with its target has been outlined and
the first to inhibit biologically important activities of
its target, the protective antigen from Bacillus anthracis.
We show how rational design based on secondary
structure predictions can also direct the use
of AEGIS to improve the stability and binding of the
aptamer to its target. The final aptamer has a dissociation
constant of ~35 nM. These results illustrate
the value of AEGIS-LIVE for those seeking to
obtain receptors and ligands without the complexities
of medicinal chemistry, and also challenge the
biophysical community to develop new tools to analyze
the spectroscopic signatures of new DNA folds
that will emerge in synthetic genetic systems replacing
standard DNA and RNA as platforms for LIVE.
Opal Absorbs and Stabilizes RNA - A Hierarchy of Prebiotic Silica
Biondi, E.; Howell, L.; Benner, S.A.
(2016) 27, A-E
A widely held 'RNA first' model proposes that RNA gave organic
matter on Earth its first access to Darwinism. Such a proposal,
which requires a mechanism to generate RNA from a prebiotic 'soup',
must also manage the intrinsic instability of any RNA so formed. Here,
we show that silicon dioxide (silica, SiO2), in the form of synthetic opal,
adsorbs and stabilizes RNA from aqueous solution. The extent of absorption
on fully amorphous silica is less, as is the extent of adsorption
on the surface of crystalline quartz. We show that the RNA adsorbed on
opal is considerably more stable than the same RNA molecule free in
aqueous solution at pH 9.5. This provides a mechanism by which any
RNA formed in a prebiotic environment could have been concentrated
and stabilized so that it could have later participated in the first Darwinian
RNA structural analysis by enzymatic digestion
Biondi E., Burke D.H.
Methods Mol Biol
, Springer (2014) 1086:41-52
Potent Inhibition of HIV-1 Reverse Transcriptase and Replication by Nonpseudoknot, "UCAA-motif" RNA Aptamers
Whatley A.S., Ditzler M.A., Lange M.J., Biondi E., Sawyer A.W., Chang J.L., Franken J.D., Burke D.H.
Mol Ther Nucleic Acids
, Nature (2013) 2:e71
Lewis acid catalysis of phosphoryl transfer from a copper(II)-NTP complex in a kinase ribozyme
Biondi E., Poudyal R.R., Forgy J.C., Sawyer A.W., Maxwell A.W., Burke D.H
Nucl. Acids Res.
A small ribozyme with dual-site kinase activity
Biondi E., Maxwell A.W.R., and Burke D.H.
Nucl. Acids Res.
Separating and analyzing sulfur-containing RNAs with organomercury gels
Biondi E, Burke DH.
Methods Mol Biol
, Springer (2012) 2012;883:111-20
Polyacrylamide gel electrophoresis is a widely used technique for RNA analysis and purification. The polyacrylamide matrix is highly versatile for chemical derivitization, enabling facile exploitation of thio-mercury chemistry without the need of tedious manipulations and/or expensive coupling reagents, which often give low yields and side products. Here, we describe the use of [(N-acryloylamino)phenyl]mercuric chloride in three-layered polyacrylamide gels to detect, separate, quantify, and analyze sulfur-containing RNAs.
Convergent donor and acceptor substrate utilization among kinase ribozymes
Biondi E., Nickens D.G., Warren S., Saran D., and Burke D.H.
Nucl. Acids Res.
Montmorillonite protection of an UV-irradiated hairpin ribozyme. Evolution of the RNA world in a mineral environment
Biondi E., Branciamore S., Maurel M.-C., and Gallori E.
BMC Evol. Biol.
(2007) 7(Suppl 2):S2
Catalytic activity of hammerhead ribozymes in a clay mineral environment: implications for the RNA World
Biondi E., Branciamore S., Fusi L., Gago, and Gallori E.
Looking for the primordial genetic honeycomb
Gallori E., Biondi E., and Branciamore S.
Orig. Life Evol. Biosph.
, Springer (2006) 36:493-499
Mineral Surfaces as a Cradle of Primordial Genetic Material
Gallori E, Biondi E, Franchi M
Life in the Universe
, ed. Seckbach J, Chela-Flores J, Owen T, Raulin F , Netherlands: Springer 145-148 (2004)
Molecules which store genetic information (DNA and RNA) are central to all life on Earth. The formation of these complex macromolecules, and ultimately life, required specific conditions, including the synthesis and polymerization of precursors (nucleotides), the protection and persistence of information polymers in a changing environment, and the expression of the "biological potential" of the molecules, i.e. their capacity to multiply and evolve. Determining how these steps occurred and how the earliest genetic molecules originated on Earth is a problem that is far from being resolved. Recent observations on the synthesis of polynucleotides on clay surfaces, the resistance of clay-adsorbed nucleic acid molecules to environmental degradation and the biological activity of clay-adsorbed DNA and RNA molecules suggest that mineral surfaces could have played a crucial role in the prebiotic formation of the biomolecules basic to life.