Identification of a region in the coiled-coil domain of Smc3 that is essential for cohesin activity.
The cohesin complex plays an important role in sister chromatin cohesion. Cohesin's core is composed of two structural maintenance of chromosome (SMC) proteins, called Smc1 and Smc3. SMC proteins are built from a globular hinge domain, a rod-shaped domain composed of long anti-parallel coiled-coil (CC), and a second globular adenosine triphosphatase domain called the head. The functions of both head and hinge domains have been studied extensively, yet the function of the CC region remains elusive. We identified a mutation in the CC of smc3 (L217P) that disrupts the function of the protein. Cells carrying the smc3-L217P allele have a strong cohesion defect and complexes containing smc3-L217P are not loaded onto the chromosomes. However, the mutation does not affect inter-protein interactions in either the core complex or with the Scc2 loader. We show by molecular dynamics and biochemistry that wild-type Smc3 can adopt distinct conformations, and that adenosine triphosphate (ATP) induces the conformational change. The L217P mutation restricts the ability of the mutated protein to switch between the conformations. We suggest that the function of the CC is to transfer ATP binding/hydrolysis signals between the head and the hinge domains. The results provide a new insight into the mechanism of cohesin activity.
Faculty of Medicine in The Galilee, Bar-Ilan University, 8 Henrietta Szold Street, P.O. Box 1589, Safed 1311502, Israel.
Ola
O
Orgil
Faculty of Medicine in The Galilee, Bar-Ilan University, 8 Henrietta Szold Street, P.O. Box 1589, Safed 1311502, Israel.
Hadar
H
Mor
Faculty of Medicine in The Galilee, Bar-Ilan University, 8 Henrietta Szold Street, P.O. Box 1589, Safed 1311502, Israel.
Avi
A
Matityahu
Faculty of Medicine in The Galilee, Bar-Ilan University, 8 Henrietta Szold Street, P.O. Box 1589, Safed 1311502, Israel Itay.Onn@biu.ac.il.
Itay
I
Onn
D000255:Adenosine Triphosphate / Q000235:genetics / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000737:chemistry / Q000235:genetics*; D011508:Chondroitin Sulfate Proteoglycans / Q000737:chemistry / Q000235:genetics*; D002843:Chromatin; D002868:Chromosomal Proteins, Non-Histone / Q000737:chemistry / Q000235:genetics*; D006801:Humans; D009154:Mutation; D009369:Neoplasms / Q000737:chemistry / Q000235:genetics*; D011487:Protein Conformation; D000072417:Protein Domains / Q000235:genetics; D017434:Protein Structure, Tertiary; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics*; D012854:Sister Chromatid Exchange / Q000235:genetics; D000097722:Cohesins; D000098550:Structural Maintenance of Chromosome Protein 1
D000255:Adenosine Triphosphate; D018797:Cell Cycle Proteins; D011508:Chondroitin Sulfate Proteoglycans; D002843:Chromatin; D002868:Chromosomal Proteins, Non-Histone; D029701:Saccharomyces cerevisiae Proteins; D000097722:Cohesins; D000098550:Structural Maintenance of Chromosome Protein 1; C120372:SMC3 protein, S cerevisiae; C492318:SMC3 protein, human