The crystal structure of YodA, an E. coli protein involved in heavy metal stress.

Anita Lewit-Bentley, Gabriel David, Simon Penel, Karine Blondeau*.

LURE, Bât. 209D, Centre Universitaire Paris-Sud, 91898 Orsay, France

*IGM, Bât. 360, Centre Universitaire Paris-Sud, 91450 Orsay, France

Heavy metals, such as mercury and cadmium, are very toxic in living organisms, which have therefore evolved various defence and control mechanisms. Even for metals that are essential for the correct functioning of living organisms, their presence within the cells has to be tightly controlled to avoid negative effects. In most cases, and certainly in the case of cadmium, the actual toxic effect is in part due to the oxidant properties of these metals.

We have solved the structure of YodA, a novel protein implicated in cadmium stress is E. coli. This protein has been suggested as a memeber of a new family of cadmium-response proteins in bacteria (1). While there is no sequence similarity to proteins with known folds, the three-dimensional structure shows that YodA is a memeber of the lipocalin/calycin family. At the same time, we show that YodA is a metalloprotein, with a high-affinity site for divalent cations such as zinc, nickel and cadmium.

We shall describe the structure of the protein and propose hypotheses for its function in bacteria.

(1) Puskarova A., Ferianc P., Kormanec J., Homerova D., Farewell A. & Nydström T. (2002). Microbiology 148, 3801-3811.