Programas Científicos
Programa de Biología Estructural y Biocomputación
Grupo de Cristalografía de Macromoléculas
Presentación Última actualización 26/03/2009
S-phase and replication
DNA replication is an essential process during cell division. The identification of the DNA helicase(s) involved in eukaryotic DNA replication is still a matter of much debate. Recently, the helicase activity of the hexameric MCM complex has been revealed as being responsible for the unwinding of DNA during S-phase in association with two partners: initiation factor Cdc45 and a four-subunit complex called GINS. In conjunction they form the CMG complex which contains ATP dependent helicase activity. We are striving to unravel the molecular mechanisms of this cellular machinery essential for eukaryotic DNA replication and are therefore combining X-ray crystallography and EM studies to decipher the structure of this complex and its components.
Mitotic kinases
Cellular growth and division are regulated by an integrated protein network which ensures the genomic integrity of all eukaryotic cells during mitosis. This cell cycle stage witnesses a massive reorganisation of cellular architecture. A trio of protein kinase families have also been involved in centrosome and mitotic regulation: the Aurora, Polo and NIMArelated kinases. There are other proteins such as kinesins which play an important role in spindle organisation. Many of these proteins are deregulated in tumoural processes. Our objective is to obtain information regarding the atomic structure and regulation of these molecules.
Structural design of homing endonucleases for gene targeting
Homing endonculeases or meganuacleases are sequence-specific enzymes which recognise large (12–45 bp) DNA target sites. These enzymes are often encoded by introns or inteins behaving as mobile genetic elements. They recognise sites that usually correspond to intron-free or intein-free genes, where they produce a DNA double-strand break (DSB). Eventually, DSB repair by homologous recombination with an intron- or inteincontaining gene, results in the insertion of the intron or intein where DSB occurred in specific loci in living cells. These results present new perspectives in a wide range of applications such as the correction of mutations linked with monogenic inherited diseases.
Our group has recently participated in the development of a chimaeric enzyme that could target mutations in the xeroderma pigmentosum gene promoting its repair. In addition we have solved the crystal structure of I-DmoI, a monomeric meganuclease, in complex with its target DNA. This structure revealed the molecular basis of I-DmoI DNA recognition, opening avenues towards engineering new specificties in this scaffold.
