Prokaryotes: not so “simple” after all

One of my research challenges for 2008 is to marry my previous work (and my “true interest”), microbial genomics, with my current project which focuses on protein kinase substrate prediction. It should prove to be fascinating and fun, provided that publications such as this one keep appearing:

Schneiker, S. et al. (2007)
Complete genome sequence of the myxobacterium Sorangium cellulosum.
Nature Biotech. 25: 1281-1289
doi:10.1038/nbt1354 | Abstract | Full Text (subscription) | PubMed

It’s years since I read a textbook but I imagine that many of them will tell you that cell signalling via serine/threonine/tyrosine phosphorylation is “eukaryotic”, whereas Bacteria and Archaea use two-component sensor/histidine kinase systems. Some far-sighted individuals have been educating us otherwise for years, but only with the advent of microbial genomics has it become apparent that eukaryotic-like protein kinases (ELKs) are widespread in prokaryotes.

Back to Sorangium. This bacterium has the largest-known bacterial genome to date (~ 13 Mbp), encodes ~ 50% more proteins than the eukaryote S. cerevisiae and – get this – has 317 putative ELKs. That’s a greater length of DNA encoding for ELKs than some entire bacterial genomes and the highest percentage of the genome devoted to ELKs of any organism (bear in mind that the human/rat/mouse kinome comprises ~ 600 kinases). On top of that Sorangium synthesises a heap of interesting secondary metabolites, including an anti-cancer compound.

Let’s hear it for those prokaryotes.