Orateur
M.
Hafez EL Sayyed
(Chromosome Dynamics Lab,CIRB - Collège de France)
Description
Catenation links between sister chromatids are formed progressively during DNA
replication and are involved in the establishment of sister chromatid cohesion. Topo IV
is a bacterial type II topoisomerase involved in the removal of catenation links both
behind replication forks and after replication during the final separation of sister circular
chromosomes. We have investigated the global DNA-binding and catalytic activity of
Topo IV in E. coli using genomic and molecular biology approaches. ChIP-seq
revealed that Topo IV interaction with the E. coli chromosome is controlled by DNA
replication. During replication, Topo IV has access to most of the genome but only
selects a few hundred specific sites determined by chromatin context for its activity.
Strong DNA-binding and catalytic activities are found at the chromosome dimer
resolution site, dif, located opposite of the replication origin. We reveal a physical and
functional interaction between Topo IV and the XerCD recombinases acting at the dif
site, modulated by the MatP protein involved in the organization of the Ter
Macrodomain. These results show that Topo IV, XerCD/dif and MatP are parts of a
network dedicated to the last step of chromosome management during the cell cycle.
Auteur principal
M.
Hafez EL Sayyed
(Chromosome Dynamics Lab,CIRB - Collège de France)
