Base Complementarity and Nucleoside Recognition in Phosphatidylnucleoside Vesicles

Abstract

Phosphatidylnucleosides that self-assemble in water to form closed liposomes have been investigated by spectroscopic methods to detect whether complementary base recognition can be achieved in spherical bilayer structures. We have prepared and characterized liposomes from 5‘-(1,2-dioleoyl-sn-glycero(3)phospho)adenosine (DOP-Ade), 5‘-(1,2-dioleoyl-sn-glycero(3)phospho)uridine (DOP-Uri), 5‘-(1,2-dioleoyl-sn-glycero(3)phospho)cytidine (DOP-Cyt), their mixtures, and liposomes formed by 5‘-(1-palmitoyl-2-oleoyl-sn-glycero(3)phospho)adenosine (POP-Ade) or 5‘-(1-palmitoyl-2-oleoyl-sn-glycero(3)phospho)uridine (POP-Uri). The 1:1 mixture of DOP-Ade and DOP-Uri liposomal solutions shows UV absorption and circular dichroism properties characteristic for base pairing, since a hypochromic effect, detected in the absorption region of the aromatic bases, is coupled to a CD intensity increase of the same band. The same effect is detected for POP-Ade liposomes mixed with POP-Uri liposomes. The hypochromic effect can be observed after three days from the mixing, and the spectroscopic feature is the same as that observed for freshly prepared liposomes formed by the mechanical 1:1 mixture of the two complementary lipids. Liposomes formed from noncomplementary phosphatidiylnucleosides, i.e. DOP-Ade and DOP-Cyt, fail to give these spectroscopic changes, supporting a specific and stoichiometric base interaction governed by Watson−Crick complementarity. The possible relevance for the origin of life of this recognition mechanism, involving bilayer self-assembling structures, is discussed.

Molecular Recognition Drives Oligonucleotide Binding to Nucleolipid Self‐Assemblies

“…[13] This effect is accompanied by a 20 % hypochromism for the 260 nm absorbance band (not shown), which supports the existence of an enhanced nucleobase stacking interaction between diC 8 PA and polyU mediated by a specific basepairing mechanism between the complementary adenine and uracil nucleobases. The appearance of the negative CD band at 290 nm seems to be a peculiar feature of this system; a similar CD behavior was found in a previous work [14] for mixed liposomes made of 5-(1,2-dioleoyl-sn-glycero(3)phospho)adenosine (DOPA) and 5-(1,2-dioleoyl-sn-glycero(3)-phospho)uridine (DOPU) in TBS. This could possibly indicate conformational variations of adenine groups on the polar head of the assembled nucleolipid, induced by cooperative interaction with uracil bases.…”

NMR Study of Micelles Formed by Monoalkylphosphoryl Nucleosides

“…To understand the properties of complementary binding and recognition in a compartmentalized system, our groups have carried out an investigation of phosphatidyl nucleosides obtained from complementary nucleo-bases such as 5'-(1,2-dialkyl-snglycero(3)phospho)adenosine and 5'-(1,2-dialkyl-sn-glycero(3)phospho)uridine [1], which form liposomes, as well as single-chain lipids such as hexadecylphosphoryladenosine, which form micelles in H 2 O [2]. These compounds can be readily synthesized by a biphasic enzymatic reaction originally developed by Shuto et al [3] [4].…”

Astrobiology and the Possibility of Life on Earth and Elsewhere…

“…For instance, it has been claimed that the Orgueil CI type chondritic meteorite could be a comet (Gounelle et al 2006), while comet-like activity (i.e. water outgassing) is observed for some objects of the asteroid belt (so called "main belt comets" or "active asteroids") (Bertini 2011;Jewitt 2012). To add confusion to the discussion of the origin of Earth's water, some authors claim that the Earth was formed from relatively dry material and that our planet's volatile components (including water) were brought in later (Albarède 2009;Albarède et al 2013), while other scenarios indicate that rocky planets were all built of material that contained enough water to form the oceans and atmospheres, and that later impact sources were relatively insignificant (Elkins-Tanton 2013; Hamano et al 2013;Wood et al 2010).…”

“…Several authors (Berti et al 1998;Bloechliger et al 1998;Luisi et al 1999;Pozzi et al 1996;Takajo et al 2001) consider that the spontaneous formation of membranes is one of the primordial steps in prebiotic evolution. One plausible model for the prebiotic formation of proto-cellular compartments, the spontaneous formation of stable vesicles, characterized by an inner and an outer space separated by a semi-permeable membrane, is a well-known and reproducible process in water.…”