Question 7: optimized energy consumption for protein synthesis.

In our previous contribution (Nierhaus, Orig Life Evol Biosph, this volume, 2007) we mentioned that life had solved the problem of energy supply in three major steps, and that these steps also mark major stages during the development of life. We further outlined a possible scenario concerning a minimal translational apparatus focusing on the essential components necessary for protein synthesis. Here we continue that consideration by addressing on one of the main problems of early life, namely avoiding wasteful energy loss. With regard to the limiting energy supply of early living systems, i.e. those of say more than 3,000 Ma, a carefully controlled and product oriented energy consumption was in demand. In recent years we learned how a bacterial cell avoids energy drain, thus being able to pump most of the energy into protein synthesis. These lessons must be followed by the design of a minimal living system, which is surveyed in this short article.