14:35 〜 14:55
[BBG01-04] Mineral surfaces select for longer RNA molecules: implication for prebiotic evolution
★Invited Papers
キーワード：鉱物、RNA、リボザイム、生命の起源
Mineral surfaces were ubiquitous on the Earth and likely played diverse roles before the emergence of life. This period of prebiotic evolution proposedly included an RNA world, where RNA molecules acted as both informational polymers and catalysts of diverse reactions. A wide range of minerals can accumulate RNA on their surfaces, and by that, minerals could have assisted the synthesis of RNA, protected RNA from degradation, and virtually compartmentalized RNA before the advent of cellular structures [1]. An old study by the Orgel group suggested another potential of mineral surfaces: the selective enrichment of longer RNAs [2]. However, this primitive idea has not been pursued further, even though the simple selective factor may have facilitated the appearance of genetic information, for example, by counteracting the preferable synthesis and faster replication of shorter RNAs. In my talk, I will introduce the interplay between RNA and mineral surfaces, including our recent work on the generality and the role of the enrichment of longer RNAs on minerals [3].
In our work, we first tested the size selection among fully random 8–24 nt RNAs of five different lengths on five kinds of mineral grains: pyrite, pyrrhotite, magnetite, calcite, and hydroxyapatite. These RNAs and minerals model ones potentially available on the early Earth. In the presence of magnesium ions, we found that longer RNAs generally enriched more than shorter ones on all five mineral surfaces. The selectivity was enhanced at higher temperatures. We further examined whether the size-selection ability can be combined with a catalytic RNA (i.e., a ribozyme). We co-incubated hydroxyapatite with a recombinase ribozyme that generates a set of products with different lengths, and found that longer products were preferentially accumulated on mineral surfaces even when coupled with the ribozyme function. Finally, to understand the underlying principle of how minerals select for longer RNAs, we constructed a mathematical model based on thermodynamics. The model essentially reproduced the experimental results, suggesting that the basis of the selection is not the chemical compositions of each mineral but surface structures. Overall, our results provided evidence that a simple and ubiquitous environmental factor, mineral surfaces, can inherently select for longer RNAs and may have assisted in the expansion of genetic information in prebiotic evolution.
References:
[1] Mizuuchi, R., Ichihashi, N. Primitive compartmentalization for the sustainable replication of genetic molecules. Life, 11 (3), 191 (2021).
[2] Gibbs, D., Lohrmann, R., Orgel, L.E. Template-directed synthesis and selective adsorption of oligoadenylates on hydroxyapatite. J. Mol. Evol., 15, 347–354 (1980).
[3] Mizuuchi, R., Blokhuis, A., Vincent, L., Nghe, P., Lehman, N., Baum, D. Mineral surfaces select for longer RNA molecules. Chem. Commun., 55, 2090–2093 (2019).
In our work, we first tested the size selection among fully random 8–24 nt RNAs of five different lengths on five kinds of mineral grains: pyrite, pyrrhotite, magnetite, calcite, and hydroxyapatite. These RNAs and minerals model ones potentially available on the early Earth. In the presence of magnesium ions, we found that longer RNAs generally enriched more than shorter ones on all five mineral surfaces. The selectivity was enhanced at higher temperatures. We further examined whether the size-selection ability can be combined with a catalytic RNA (i.e., a ribozyme). We co-incubated hydroxyapatite with a recombinase ribozyme that generates a set of products with different lengths, and found that longer products were preferentially accumulated on mineral surfaces even when coupled with the ribozyme function. Finally, to understand the underlying principle of how minerals select for longer RNAs, we constructed a mathematical model based on thermodynamics. The model essentially reproduced the experimental results, suggesting that the basis of the selection is not the chemical compositions of each mineral but surface structures. Overall, our results provided evidence that a simple and ubiquitous environmental factor, mineral surfaces, can inherently select for longer RNAs and may have assisted in the expansion of genetic information in prebiotic evolution.
References:
[1] Mizuuchi, R., Ichihashi, N. Primitive compartmentalization for the sustainable replication of genetic molecules. Life, 11 (3), 191 (2021).
[2] Gibbs, D., Lohrmann, R., Orgel, L.E. Template-directed synthesis and selective adsorption of oligoadenylates on hydroxyapatite. J. Mol. Evol., 15, 347–354 (1980).
[3] Mizuuchi, R., Blokhuis, A., Vincent, L., Nghe, P., Lehman, N., Baum, D. Mineral surfaces select for longer RNA molecules. Chem. Commun., 55, 2090–2093 (2019).