Limits...
Characterization of RNA-Like Oligomers from Lipid-Assisted Nonenzymatic Synthesis: Implications for Origin of Informational Molecules on Early Earth.

Mungi CV, Rajamani S - Life (Basel) (2015)

Bottom Line: The resultant products were characterized to understand their chemical makeup.Formation of such oligomers would have permitted sampling of a large variety of bases on a preformed polymer backbone, resulting in "prebiotic phosphodiester polymers" prior to the emergence of modern RNA-like molecules.This suggests that primitive genetic polymers could have utilized bases that conferred greater N-glycosyl bond stability, a feature crucial for information propagation in low pH and high temperature regimes of early Earth.

View Article: PubMed Central - PubMed

Affiliation: Indian Institute of Science Education and Research (IISER), Pune, Maharashtra 411008, India. cvmungi@students.iiserpune.ac.in.

ABSTRACT
Prebiotic polymerization had to be a nonenzymatic, chemically driven process. These processes would have been particularly favored in scenarios which push reaction regimes far from equilibrium. Dehydration-rehydration (DH-RH) cycles are one such regime thought to have been prevalent on prebiotic Earth in niches like volcanic geothermal pools. The present study defines the optimum DH-RH reaction conditions for lipid-assisted polymerization of nucleotides. The resultant products were characterized to understand their chemical makeup. Primarily, our study demonstrates that the resultant RNA-like oligomers have abasic sites, which means these oligomers lack information-carrying capability because of losing most of their bases during the reaction process. This results from low pH and high temperature conditions, which, importantly, also allows the formation of sugar-phosphate oligomers when ribose 5'-monophosphates are used as the starting monomers instead. Formation of such oligomers would have permitted sampling of a large variety of bases on a preformed polymer backbone, resulting in "prebiotic phosphodiester polymers" prior to the emergence of modern RNA-like molecules. This suggests that primitive genetic polymers could have utilized bases that conferred greater N-glycosyl bond stability, a feature crucial for information propagation in low pH and high temperature regimes of early Earth.

No MeSH data available.


Mass profile of HRMS analysis obtained for Cyc10 sample of 5 mM rMP reaction, which was subjected to DH-RH cycles at pH 2 with 1 mM POPC. Observed mass numbers suggest that both cyclic and linear oligomers of rMP are formed, resulting in a cluster of mass peaks for each oligomer. Chemical identities of the various peaks are tabulated in Table 2. Heptamers may also be discerned but with less confidence due to reduced abundance.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4390841&req=5

life-05-00065-f009: Mass profile of HRMS analysis obtained for Cyc10 sample of 5 mM rMP reaction, which was subjected to DH-RH cycles at pH 2 with 1 mM POPC. Observed mass numbers suggest that both cyclic and linear oligomers of rMP are formed, resulting in a cluster of mass peaks for each oligomer. Chemical identities of the various peaks are tabulated in Table 2. Heptamers may also be discerned but with less confidence due to reduced abundance.

Mentions: The fact that even one DH-RH cycle resulted in several oligomer peaks (Figure 8) indicated that the kinetics for phosphodiester formation are probably very different in the case of 5'-NMP reactions versus rMP reactions. Formation of much higher oligomers was observed in chromatograms obtained from higher cycles, as indicated in Figure 8. Figure 9 shows the mass spectrum for an rMP-based reaction mixture obtained after 10 cycles of DH-RH at pH2. The observed mass numbers suggest that both cyclic and linear oligomers of rMP are formed in these reactions. Strand cyclization is known to occur as a result of intramolecular condensation, which is observed frequently during polymerization [21]. Formation of these sugar-phosphate backbones demonstrates the possibility of easily forming such oligomers under the low pH and high temperature conditions of volcanic geothermal pools. The exact chemical nature of these sugar-phosphate polymers is currently under investigation.


Characterization of RNA-Like Oligomers from Lipid-Assisted Nonenzymatic Synthesis: Implications for Origin of Informational Molecules on Early Earth.

Mungi CV, Rajamani S - Life (Basel) (2015)

Mass profile of HRMS analysis obtained for Cyc10 sample of 5 mM rMP reaction, which was subjected to DH-RH cycles at pH 2 with 1 mM POPC. Observed mass numbers suggest that both cyclic and linear oligomers of rMP are formed, resulting in a cluster of mass peaks for each oligomer. Chemical identities of the various peaks are tabulated in Table 2. Heptamers may also be discerned but with less confidence due to reduced abundance.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4390841&req=5

life-05-00065-f009: Mass profile of HRMS analysis obtained for Cyc10 sample of 5 mM rMP reaction, which was subjected to DH-RH cycles at pH 2 with 1 mM POPC. Observed mass numbers suggest that both cyclic and linear oligomers of rMP are formed, resulting in a cluster of mass peaks for each oligomer. Chemical identities of the various peaks are tabulated in Table 2. Heptamers may also be discerned but with less confidence due to reduced abundance.
Mentions: The fact that even one DH-RH cycle resulted in several oligomer peaks (Figure 8) indicated that the kinetics for phosphodiester formation are probably very different in the case of 5'-NMP reactions versus rMP reactions. Formation of much higher oligomers was observed in chromatograms obtained from higher cycles, as indicated in Figure 8. Figure 9 shows the mass spectrum for an rMP-based reaction mixture obtained after 10 cycles of DH-RH at pH2. The observed mass numbers suggest that both cyclic and linear oligomers of rMP are formed in these reactions. Strand cyclization is known to occur as a result of intramolecular condensation, which is observed frequently during polymerization [21]. Formation of these sugar-phosphate backbones demonstrates the possibility of easily forming such oligomers under the low pH and high temperature conditions of volcanic geothermal pools. The exact chemical nature of these sugar-phosphate polymers is currently under investigation.

Bottom Line: The resultant products were characterized to understand their chemical makeup.Formation of such oligomers would have permitted sampling of a large variety of bases on a preformed polymer backbone, resulting in "prebiotic phosphodiester polymers" prior to the emergence of modern RNA-like molecules.This suggests that primitive genetic polymers could have utilized bases that conferred greater N-glycosyl bond stability, a feature crucial for information propagation in low pH and high temperature regimes of early Earth.

View Article: PubMed Central - PubMed

Affiliation: Indian Institute of Science Education and Research (IISER), Pune, Maharashtra 411008, India. cvmungi@students.iiserpune.ac.in.

ABSTRACT
Prebiotic polymerization had to be a nonenzymatic, chemically driven process. These processes would have been particularly favored in scenarios which push reaction regimes far from equilibrium. Dehydration-rehydration (DH-RH) cycles are one such regime thought to have been prevalent on prebiotic Earth in niches like volcanic geothermal pools. The present study defines the optimum DH-RH reaction conditions for lipid-assisted polymerization of nucleotides. The resultant products were characterized to understand their chemical makeup. Primarily, our study demonstrates that the resultant RNA-like oligomers have abasic sites, which means these oligomers lack information-carrying capability because of losing most of their bases during the reaction process. This results from low pH and high temperature conditions, which, importantly, also allows the formation of sugar-phosphate oligomers when ribose 5'-monophosphates are used as the starting monomers instead. Formation of such oligomers would have permitted sampling of a large variety of bases on a preformed polymer backbone, resulting in "prebiotic phosphodiester polymers" prior to the emergence of modern RNA-like molecules. This suggests that primitive genetic polymers could have utilized bases that conferred greater N-glycosyl bond stability, a feature crucial for information propagation in low pH and high temperature regimes of early Earth.

No MeSH data available.