It is known that even the simplest living cells existing on the Earth have several hundredgenes, with hundreds of expressed proteins that catalyse simultaneously hundreds ofreactions within the same tiny compartment the cell representing a maize of anenormous and fascinating complexity. On the other hand, if we think to early cells orprotocells (those that played a key role in the origin of life), it is conceivable that theycould display some living properties with a minor number of biochemicalcomponents. In particular, the present huge complexity is most likely resulted frombillions of years of evolution, that developed a series of defence and securitymechanisms, redundancies, metabolic loops and highly sophisticated regulatoryprocesses.These considerations elicit the question, whether such a complexity is reallyessential for life, or whether instead cellular life might be possible with a much smallernumber of components. In this chapter we describe the basis of the concepts ofminimal genome and of the minimal cell.The question of the minimal genome and minimal cell has been considered sincemany years, and one should in particular recall the work of Morowitz (1967), who,based on the enzymatic components of primary metabolism, estimated that the size of aminimal cell should be about one-tenth smaller than Mycoplasma genitalium.Significant earlier insights into the field are those by Jay and Gilbert (1987) as well asby Woese (1983) and Dyson (1982). More recently, the reviews by Deamer andcoworkers (Pohorille and Deamer, 2002) and Luisis group (Luisi 2002, Oberholzer andLuisi, 2002) have sharpened the question and brought it in the perspective of modernmolecular tools. In fact, the last years have seen a significant revival of interest in thefield of the minimal cell, as witnessed for example by two international meetings held in2004 on the subject (Szathmáry, 2005). A more detailed version of a review on theminimal cell is in press elsewhere (Luisi et al., 2005).
Stano, P., Ferri, F., Luisi, P.L. (2006). From the minimal genome to the minimal cell: theoretical and experimental investigations.. In Life as We Know It (pp.181-198). Dordrecht : Springer.