Being notorious for insatiable curiosity among family members and friends for all of my youth I studied biochemistry at Free University Berlin with the stilted aim to learn: how life functions. Gladly enough I caught the trailing edge of the heroic times of molecular biology in the mid-eighties while doing my PhD in 'ribosomology' at the Max-Planck-Institute for Molecular Genetics in Berlin.
In my first postdoc year then, I studied together with a PhD student a small abundant (+)mating type-specific hyphal surface protein of Absidia glauca, a modest fungus from the Zygomycetes family. Eventually we could get hold of the gene encoding this protein, extravagantly located on one of the >100 different low-copy plasmids that this fungus entertains for whatever reason. During a prolonged trip to Latin America I received the final proof of the gene's location on a plasmid by a wordless fax message: just the picture you see here on the right and my colleague's signature. Although we never found out how these plasmids replicate the very picture was my admission ticket to Walter Messer's lab at the MPI for Molecular Genetics with whom I studied replication initiation in E. coli for several years as postdoc. During a detour to the world of bacteriophages I learned that asking for every theoretically imaginable replication mechanism — θ- or σ-type, tRNA primed, protein primed, transcription-dependent, recombination-dependent, just to name a few — there is at least one phage family answering: yes we can. I'm sticking to the topic chromosome replication ever since and my curiosity hasn't diminished yet, there are still more questions than answers. Asked by Elio to contribute to this blog I will try to share with the readers these questions & answers, some of them.
Christoph Weigel is a lecturer at the Institute of Biotechnology of Technical University Berlin, Germany.