Exactly one year ago today I defended my doctoral thesis in Delft. Fast-forward one year, and I find myself writing these words in the California sun. How different life has become! Having embarked on an exciting new project, I am now challenged to think about a whole new universe of fascinating problems. Yet I do enjoy looking back every now and then to remember the good times of grad school. The good times of a protein in a box.
What is life? At the very least it is a concept that we humans find surprisingly difficult to define. Though generally wet and dynamic1, arguments about what defines life inevitably involve terms like ‘reproduction’, ‘growth’, and ‘adaptation’ – matters very common to cells and viruses alike, yet whether the latter belong to the category of living things is a matter of ongoing debate. For the purpose of this thesis (as well as for my own understanding), I adopt a less materialistic and more conceptual definition of life:
Life is a process brought forward by the self-organization of molecules, a process that seemingly violates the second law of thermodynamics2 as it increasingly acquires and maintains information over timescales that vastly exceed the lifetime of the molecules holding this information.
In this manner the distinction between a virus and a cell becomes rather meaningless: viruses are just as much part of the process that we know as ‘life’ as a homo sapiens like you or me is.3 In addition, it allows me to conveniently classify my thesis work as “an effort to gain better understanding of the molecular processes and building blocks of life”. Though this classification is rather broad – as myriads of doctoral theses written over the past century or so belong to this category – my thesis belongs to a relatively small and novel subcategory of the ‘gaining insight into the building blocks of life’ class by making use of two concepts: single-molecule and bottom-up approach.