Origin of Biological Nucleic Acids and the First Genetic System (The Progene Hypothesis)

Abstract

The most accepted concept of the origin of nucleic acids and life is the RNA world hypothesis that is supported by many scientists. There are very strong objections against this hypothesis (problems of selection of compounds in prebiotic conditions, processivity of polynucleotide synthesis without protein polymerases, arising of the genetic code and translation). In order to overcome these obstacles and to explain how the first biological nucleic acid (the first gene) arises simultaneously with a specific protein (a processive polymerase) forming a bimolecular genetic system, I have proposed an alternative hypothesis (the progene hypothesis). According to this hypothesis, the bimolecular genetic system emerges not from mononucleotides and monoamino acids, but from progenes, namely, trinucleotides aminoacylated on 3'-end by a non-random amino acid (NpNpNp~pX~Aa, where N -deoxyribo-or ribonucleoside, p -phosphate, X -a bifunctional agent, for example ribose, Aa -amino acid, ~ macroerge bond). The progenes are used as the only substrates for interconnected synthesis of a polynucleotide and a polypeptide. The growth of the system "polynucleotide -polypeptide" is controlled by the enzymatic properties of the growing polypeptide, and the bimolecular genetic system emerges as an extremely rare event. The progene forming mechanism (NpNp + Np~pX~Aa) makes it possible to explain the emergence of the prebiotic physicochemical group genetic code, as well as the selection of organic compounds for the future genetic system from the racemic heterogeneous environment. The bimolecular genetic system is reproduced on a progene basis via replication-transcription-translation (the first molecular genetic process) that is similar to its modern counterparts. Nothing is required for the emergence and reproduction of the bimolecular genetic system except for progenes and conditions for their formation, including lipid vesicles and short oligonucleotides (2-6 bases).