Genome minimal

Very few self-sufficient viruses have only 60 protein chains in their shells. The satellite viruses do not themselves encode all of the functions required for their replication and are therefore not self-sufficient. The first satellite virus to be discovered, satellite tobacco necrosis virus, which is also one of the smallest known with a diameter of 180 A, has a protein shell of 60 subunits. This virus cannot replicate on its own inside a tobacco cell but needs a helper virus, tobacco necrosis virus, to supply the functions it does not encode. The RNA genome of the satellite virus has only 1120 nucleotides, which code for the viral coat protein of 195 amino acids but no other protein. With this minimal genome the satellite viruses are obligate parasites of the viruses that parasitize cells. 

This definition does not identify one special structure it is a descriptive term for a variety of minimal cells. Although there is no consensus on this definition, scientists do agree on the main points. Thus, a minimal genome should have 200-300 genes. The question arises as to whether it is conceivable that this number can be further reduced, or whether we need to devise other, as yet unknown, precursor systems. 

Minimal genome The minimal gene set for an organism (170 genes) in a minimum volume cell... 

Let us now go back to the more familiar DNA world with the question of the minimal genome. This has been considered by several authors, for example, Mushegian and Koonin (1996) Shimkets (1998) Mushegian (1999) Koonin (2000) Kolisny-chenko etal. (2002) 2002) Luisi etal (2002) Gil etal. (2004) Islas etal. (2004). Table 11.1 gives an overview of some salient contributions in the field. 

Mushegian and Koonin (1996) calculated an inventory of 256 genes that represents the amount of DNA required to sustain a modern type of minimal cell under permissible conditions. This number, as indicated later by Koonin (2000), is quite similar to the values of viable minimal genome sizes inferred by site-directed gene disruptions in B. subtilis (Itaya, 1995) and transposon-mediated... 

On the subject of this last work, one may recall that the notion of minimal genome is approached in quite a different way hy Craig Venter and his group. In work carried out at the Institute for Genomic Research in Rockville, Maryland, a team led hy Clyde Hutchinson knocked out genes from a M. genitalium bacterium... 

Further speculations on the minimal genome Table 11.3. Core of a minimal bacterial gene set ... 

What can be done in order to approach the construction of the minimal cell In principle, the complexity of the core of the liposomes should be increased so as to reach the minimal genome. 

Gil, R., Sabater-Munoz, B., Latorre, A., Silva, F. J., and Moya, A. (2002). Extreme genome reduction in Buchnera spp toward the minimal genome needed for symbiotic life. Proc. Natl. Acad. ScL USA, 99,4454-8. 

Itaya, M. (1995). An estimation of the minimal genome size required for life. FEES Lett., 362, 257-60. 

Mushegian, A. (1999). The minimal genome concept. Curr. Opin. Genetics Develop., 9, 709-714. 

P. Stano, F. Feni, P. L. Luisi, From the minimal genome to the minimal cell theoretical and experimental investigations, in "Life Ai We Know If, J. Seckbach (Ed.), Springer, Berhn, 181-198, 2006. 

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