PhD Student Geoffroy Gaschignard ( Advisors : Isabelle Callebaut, Manuela Dezi et Fériel Skouri-Panet. Grant ANR Harley)

Biomineralization is all the processus that leads to the formation of rock by living beings. It has a crucial role in carbon and mineral cycle. In 2012, in the lab, the Biomin team observed a new biomineralizing phenotype : intracellular biomineralization in cyanobacteria. It is caracterized by the presence of alkaline-earth carbonate inside the cells. A comparative genomic study revealed that this phenotype is linked to the presence of a specific gene in the cyanobacteria. This gene, called ccya, code for one novel and unknown protein called calcyanin. The goal of this phd is to uncover the role of this protein in the biomineralization phenotype. To achieve this we are aiming at solving the 3D structure of the protein, by combining two approaches. First, an experimental approach in which we express the protein in E.coli, to purify it and to crystallize it to solve the 3D structure through X-ray diffraction. Then a bioinformatic approach, in which we look for sequence similarities between our protein and other already caracterized protein, and we modelize the protein. Thanks to that, we will formulate hypothesis on the function(s) of this protein and on the mecanism of rock formation in the cells.

Figure : Model of the 3D structure of one of the domains of calcyanin

@ Geoffroy Gaschignard