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SUMMARY Next generation sequencing (NGS) technologies, which allow high speed automated DNA sequencing, DNA sequence analysis and comparisons using big data algorithms are being used more and more in medical diagnosis, to provide prognosis information and for choosing a treatment that best fits the patient. The French “Academie nationale de medecine ” (ANM) and “ Academie des technologies “ (NATF) jointly stress the scientific and medical importance of these technologies and call for bringing together strengths of the national computer science industry and the medical community in a public-private consortium in order to build a Demonstrator and Center network filling up the growing gap between France and the most advanced countries in this field with great potential. They underline also common pitfalls which need to be addressed in technic, legal, economic, education and ethics issues, in order to make this complex project a success.

The exponential increase in genome sequencing output has led to the accumulation of thousands of predicted genes lacking a proper functional annotation. Among this mass of hypothetical proteins, enzymes catalyzing new reactions or using novel ways to catalyze already known reactions might still wait to be identified. Here, we provide a structural and biochemical characterization of the 3-keto-5-aminohexanoate cleavage enzyme (Kce), an enzymatic activity long known as being involved in the anaerobic fermentation of lysine but whose catalytic mechanism has remained elusive so far. Although the enzyme shows the ubiquitous triose phosphate isomerase (TIM) barrel fold and a Zn2+ cation reminiscent of metal-dependent class II aldolases, our results based on a combination of x-ray snapshots and molecular modeling point to an unprecedented mechanism that proceeds through deprotonation of the 3-keto-5-aminohexanoate substrate, nucleophilic addition onto an incoming acetyl-CoA, intramolecular transfer of the CoA moiety, and final retro-Claisen reaction leading to acetoacetate and 3-aminobutyryl-CoA. This model also accounts for earlier observations showing the origin of carbon atoms in the products, as well as the absence of detection of any covalent acyl-enzyme intermediate. Kce is the first representative of a large family of prokaryotic hypothetical proteins, currently annotated as the “domain of unknown function” DUF849.