Unknown unknowns: essential genes in quest for function

The experimental design of a minimal synthetic genome revealed the presence of a large number of genes without ascribed function, in part because the abstract laws of life must be implemented within ad hoc material contraptions. Creating a function needs recruitment of some pre-existing structure and this reveals kludges in their set-up and history. Here, we show that looking for functions as an engineer would help in discovery of a significant number of those, proposed together with conceptual handles allowing investigators to pursue this endeavour in other contexts.