scholarly journals A role for the Smc3 hinge domain in the maintenance of sister chromatid cohesion

2017 ◽  
Author(s):  
Brett Robison ◽  
Vincent Guacci ◽  
Douglas Koshland

AbstractCohesin is a conserved protein complex required for sister chromatid cohesion, chromosome condensation, DNA damage repair, and regulation of transcription. Although cohesin functions to tether DNA duplexes, the contribution of its individual domains to this activity remains poorly understood. We interrogated the Smc3p subunit of cohesin by random insertion mutagenesis. Analysis of a mutant in the Smc3p hinge revealed an unexpected role for this domain in cohesion maintenance and condensation. Further investigation revealed that the Smc3p hinge functions at a step following cohesin’s stable binding to chromosomes and independently of Smc3p’s regulation by the Eco1p acetyltransferase. Hinge mutant phenotypes resemble loss of Pds5p, which binds opposite the hinge near Smc3p’s head domain. We propose that a specific conformation of the Smc3p hinge and Pds5p cooperate to promote cohesion maintenance and condensation.

2010 ◽  
Vol 188 (3) ◽  
pp. 335-349 ◽  
Author(s):  
Rihui Yan ◽  
Sharon E. Thomas ◽  
Jui-He Tsai ◽  
Yukihiro Yamada ◽  
Bruce D. McKee

Sister chromatid cohesion is essential to maintain stable connections between homologues and sister chromatids during meiosis and to establish correct centromere orientation patterns on the meiosis I and II spindles. However, the meiotic cohesion apparatus in Drosophila melanogaster remains largely uncharacterized. We describe a novel protein, sisters on the loose (SOLO), which is essential for meiotic cohesion in Drosophila. In solo mutants, sister centromeres separate before prometaphase I, disrupting meiosis I centromere orientation and causing nondisjunction of both homologous and sister chromatids. Centromeric foci of the cohesin protein SMC1 are absent in solo mutants at all meiotic stages. SOLO and SMC1 colocalize to meiotic centromeres from early prophase I until anaphase II in wild-type males, but both proteins disappear prematurely at anaphase I in mutants for mei-S332, which encodes the Drosophila homologue of the cohesin protector protein shugoshin. The solo mutant phenotypes and the localization patterns of SOLO and SMC1 indicate that they function together to maintain sister chromatid cohesion in Drosophila meiosis.


2017 ◽  
Author(s):  
Madhusudhan Srinivasan ◽  
Johanna C. Scheinost ◽  
Naomi J. Petela ◽  
Thomas G. Gligoris ◽  
Maria Wissler ◽  
...  

SummaryAs predicted by the notion that sister chromatid cohesion is mediated by entrapment of sister DNAs inside cohesin rings, there is a perfect correlation between co-entrapment of circular minichromosomes and sister chromatid cohesion in a large variety of mutants. In most cells where cohesin loads onto chromosomes but fails to form cohesion, loading is accompanied by entrapment of individual DNAs. However, cohesin with a hinge domain whose positively charged lumen has been neutralized not only loads onto and translocates along chromatin but also organizes it into chromatid-like threads, despite largely failing to entrap DNAs inside its ring. Thus, cohesin engages chromatin in a non-topological as well as a topological manner. Our finding that hinge mutations, but not fusions between Smc and kleisin subunits, abolish entrapment suggests that DNAs may enter cohesin rings through hinge opening. Lastly, mutation of three highly conserved lysine residues inside the Smc1 moiety of Smc1/3 hinges abolishes all loading without affecting cohesin’s initial recruitment to CEN loading sites or its ability to hydrolyze ATP. We suggest that loading and translocation are mediated by conformational changes in cohesin’s hinge driven by cycles of ATP hydrolysis.


2018 ◽  
Vol 29 (3) ◽  
pp. 339-355 ◽  
Author(s):  
Brett Robison ◽  
Vincent Guacci ◽  
Douglas Koshland

A screen of cohesin subunit Smc3 reveals that its hinge is a nexus controlling the maintenance of sister chromatid cohesion and condensation.


Genetics ◽  
2002 ◽  
Vol 160 (2) ◽  
pp. 805-813 ◽  
Author(s):  
Edward S Davis ◽  
Lucia Wille ◽  
Barry A Chestnut ◽  
Penny L Sadler ◽  
Diane C Shakes ◽  
...  

Abstract Two genes, originally identified in genetic screens for Caenorhabditis elegans mutants that arrest in metaphase of meiosis I, prove to encode subunits of the anaphase-promoting complex or cyclosome (APC/C). RNA interference studies reveal that these and other APC/C subunits are essential for the segregation of chromosomal homologs during meiosis I. Further, chromosome segregation during meiosis I requires APC/C functions in addition to the release of sister chromatid cohesion.


Genetics ◽  
1994 ◽  
Vol 136 (3) ◽  
pp. 953-964 ◽  
Author(s):  
D P Moore ◽  
W Y Miyazaki ◽  
J E Tomkiel ◽  
T L Orr-Weaver

Abstract We describe a Drosophila mutation, Double or nothing (Dub), that causes meiotic nondisjunction in a conditional, dominant manner. Previously isolated mutations in Drosophila specifically affect meiosis either in females or males, with the exception of the mei-S332 and ord genes which are required for proper sister-chromatid cohesion. Dub is unusual in that it causes aberrant chromosome segregation almost exclusively in meiosis I in both sexes. In Dub mutant females both nonexchange and exchange chromosomes undergo nondisjunction, but the effect of Dub on nonexchange chromosomes is more pronounced. Dub reduces recombination levels slightly. Multiple nondisjoined chromosomes frequently cosegregate to the same pole. Dub results in nondisjunction of all chromosomes in meiosis I of males, although the levels are lower than in females. When homozygous, Dub is a conditional lethal allele and exhibits phenotypes consistent with cell death.


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