Figure 1.
The concept of master functions and networks in bacterial cells. (a) Two functions can be linked to one another by informational relationships (arrows) resulting from sharing, exchanging information or action on one another to form a functional cyclic network. (b) A master function F can be defined as a higher order functional network of lower functional entities (A–E) that can themselves involve multiple functional operations (e.g. A1, C2, D4, etc.) in informational relationship with one another. (c) Example of a functional cyclic network: the minimal cellular operating system (COS) network comprises biological macromolecules and pathways supposed necessary and sufficient for replication (and reproduction) from small molecule nutrients diffusing through the bilayer lipid vesicle (figure adapted from Forster & Church [21]). Biomolecules and chemical reactions are coloured according to the biochemical pathway which they belong to: DNA replication (blue), RNA transcription (red), RNA processing (green), ribosome assembly (violet), protein translation (black) and post-translational processing (orange). MFT: methionyl-tRNAfMet formyltransferase. Circled letters correspond to steps subjected to complementation experiments described in table 1 (A [22,23]; B [24,25]; C [26,27]; D [28,29]; E [30]).