Journal of Biosciences

, Volume 27, Issue 2, pp 165–186 | Cite as

Origins of gene, genetic code, protein and life: comprehensive view of life systems from a GNC-SNS primitive genetic code hypothesis

  • K. Ikehara


We have investigated the origin of genes, the genetic code, proteins and life using six indices (hydropathy, α-helix, β-sheet and β-turn formabilities, acidic amino acid content and basic amino acid content) necessary for appropriate three-dimensional structure formation of globular proteins. From the analysis of microbial genes, we have concluded that newly-born genes are products of nonstop frames (NSF) on antisense strands of microbial GC-rich genes [GC-NSF(a)] and from SNS repeating sequences [(SNS)n] similar to the GC-NSF(a) (S and N mean G or C and either of four bases, respectively). We have also proposed that the universal genetic code used by most organisms on the earth presently could be derived from a GNC-SNS primitive genetic code. We have further presented the [GADV]-protein world hypothesis of the origin of life as well as a hypothesis of protein production, suggesting that proteins were originally produced by random peptide formation of amino acids restricted in specific amino acid compositions termed as GNC-, SNS and GC-NSF(a)-0th order structures of proteins. The [GADV]-protein world hypothesis is primarily derived from the GNC-primitive genetic code hypothesis. It is also expected that basic properties of extant genes and proteins could be revealed by considerations based on the scenario with four stages


GNC-SNS primitive genetic code hypothesis origin of genes origin of genetic code origin of life origin of proteins 


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  1. Dill K A 1990 Dominant forces in protein folding;Biochemistry 29 7133–7155PubMedCrossRefGoogle Scholar
  2. Gesteland R F, Cech T R and Atkins J F 1999The RNA world (New York: Cold Spring Harbor Laboratory Press)Google Scholar
  3. Gilbert W 1986 The RNA world;Nature (London) 319 618CrossRefGoogle Scholar
  4. Gilbert W, de Souza S J and Long M 1997 Origins of genes;Proc. Natl. Acad. Sci. USA 94 7698–7703PubMedCrossRefGoogle Scholar
  5. Guerrier-Takada C, Gardiner K, Marsh T, Pace N and Altman S 1983 The RNA moiety of ribonuclease P is catalytic subunit of the enzyme;Cell 35 849–857PubMedCrossRefGoogle Scholar
  6. Ikehara K 1998a Origin and evolution of the genetic code (based on the novel SNS hypothesis) (in Japanese);Seibutukagaku 50 44–54Google Scholar
  7. Ikehara K 1998b A possible evolutionary pathway of the genetic code deduced from the SNS hypothesis;Viva Origino 26 311–320Google Scholar
  8. Ikehara K 1999 Is the RNA-world hypothesis of prebiotic evolution correct? (life was originated from the prebiotic protein world!) (in Japanese);Seibutukagaku 51 43–53Google Scholar
  9. Ikehara K 2000 Life was born from proteins!?—[GADV]-protein world hypothesis—(in Japanese);Kagaku 55 14–19Google Scholar
  10. Ikehara K, Amada F, Yoshida S, Mikata Y and Tanaka A 1996 A possible origin of newly-born bacterial genes: significance of GC-rich nonstop frame on antisense strand;Nucleic Acids Res. 24 4249–4255PubMedCrossRefGoogle Scholar
  11. Ikehara K and Okazawa E 1993 Unusually biased nucleotide sequences on sense strands ofFlavobacterium sp. genes produce nonstop frames on the corresponding antisense strands;Nucleic Acids Res. 21 2193–2199PubMedCrossRefGoogle Scholar
  12. Ikehara K, Omori Y, Arai R and Hirose A 2002 A novel theory on the origin of the genetic code: a GNC-SNS hypothesis;J. Mol. Evol. (in press)Google Scholar
  13. Ikehara K and Yoshida S 1998 SNS hypothesis on the origin of the genetic code;Viva Origino 26 301–310Google Scholar
  14. Jimenez-Sanches A 1995 In the origin and evolution of the genetic code;J. Mol. Evol. 41 712–716CrossRefGoogle Scholar
  15. Kruger K, Grabowski P J, Zaug A J, Sands J, Gottschling D E and Cech T R 1982 Self-splicing RNA: Autoexcision and autocyclization of the ribosomal RNA intervening sequence ofTetrahymena;Cell 31 147–157PubMedCrossRefGoogle Scholar
  16. Miller S L and Orgel L E 1975The origin of life on the earth (New York: Prentice-Hall)Google Scholar
  17. Ohno S 1970Evolution by gene duplication (Heiderberg: Springer)Google Scholar
  18. Osawa S 1995Evolution of the genetic code (Oxford: Oxford University Press)Google Scholar
  19. Stryer L 1988Biochemistry 3rd edition (New York: W H Freeman)Google Scholar
  20. Sueoka N 1988 Directional mutation pressure and neutral molecular evolution;Proc. Natl. Acad. Sci. USA 85 2653–2657PubMedCrossRefGoogle Scholar
  21. Voet D, Voet J G and Pratt C W 1999Fundamentals of biochemistry (New York: John Wiley)Google Scholar

Copyright information

© Indian Academy of Sciences 2002

Authors and Affiliations

  • K. Ikehara
    • 1
  1. 1.Department of Chemistry, Faculty of ScienceNara Women’s UniversityNaraJapan

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