The combination of these results suggest that Ctf7p plays a role in cohesion distinct from Mcd1p.
Drosophila ORC localizes to open chromatin and marks sites of cohesin complex loading. Previous Section Next Section.
To investigate the function of Ctf7p in vivo, three temperature-sensitive alleles of CTF7 were obtained by a PCR-based mutagenesis strategy and integrated into the genome see Materials and Methods.
Chromosomal proteins that prevent premature separation of sister chromatids. Sister chromatid cohesion is apparently established during S phase and maintained until anaphase onset.
Cell 114: Of note, HEAT repeats are also present within Pds5, a cohesin-binding partner with complex and paradoxical roles in cohesion establishment and maintenance, as discussed below.
Rieder C. Therefore, although there is evidence from vertebrate cell chromosomes that cohesion is differentially regulated along the length of the chromosome Sumner 1991 , Ctf7p and Mcd1p appear to function in aspects of cohesion that are common to all regions of the chromosome.
Attempts to detect such reloading via timed inactivation of the Scc2—Scc4 complex have thus far proven unsuccessful Lengronne et al. These genetic interactions link Ctf7p with proteins that are required during S phase, consistent with our mapping experiments, and together suggest that the establishment of sister chromatid cohesion is facilitated by components of the DNA replication machinery.
Annu Rev Genet 43: In metaphase-arrested cells, however, the chromosome arms are no longer paired, whereas the centromeres can remain paired for an extended period of time Sumner 1991. However generated, entrapment of the nascent sister DNAs is likely to enhance fork stability by enabling homology-dependent pathways of fork repair and restart.
In contrast, the yeast Scc2—Scc4 complex associates with chromatin and loads cohesin even when pre-RC assembly is prevented. Previous Section.
Based on concepts derived from prokaryotic DNA replication—such as the formation of large DNA loops that enable coordinated leading and lagging strand synthesis Alberts et al. Genome Res 20: Cdc7—Drf1 kinase links chromosome cohesion to the initiation of DNA replication in Xenopus egg extracts.
Paulovich A. Mol Cell 33: Previous Section Next Section.
Connelly C. One possibility was that defects in sister chromosome cohesion allowed sister chromatids to separate prematurely, resulting in the movement of disjoined sisters toward the spindle poles.
Considerable progress has been made toward understanding how sister chromatids become connected to one another during S phase. POL30 was the only gene found in a genome-wide screen that, at high copy, suppressed ctf7 temperature sensitivity and chromosome loss.