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PLoS Genet. 2017 Mar 16;13(3):e1006614. doi: 10.1371/journal.pgen.1006614. eCollection 2017 Mar.

An SMC-like protein binds and regulates Caenorhabditis elegans condensins.

Author information

1
Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA, United States of America.
2
Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA, United States of America.
3
Department of Biology, College of the Holy Cross, Worcester, MA, United States of America.

Abstract

Structural Maintenance of Chromosomes (SMC) family proteins participate in multisubunit complexes that govern chromosome structure and dynamics. SMC-containing condensin complexes create chromosome topologies essential for mitosis/meiosis, gene expression, recombination, and repair. Many eukaryotes have two condensin complexes (I and II); C. elegans has three (I, II, and the X-chromosome specialized condensin IDC) and their regulation is poorly understood. Here we identify a novel SMC-like protein, SMCL-1, that binds to C. elegans condensin SMC subunits, and modulates condensin functions. Consistent with a possible role as a negative regulator, loss of SMCL-1 partially rescued the lethal and sterile phenotypes of a hypomorphic condensin mutant, while over-expression of SMCL-1 caused lethality, chromosome mis-segregation, and disruption of condensin IDC localization on X chromosomes. Unlike canonical SMC proteins, SMCL-1 lacks hinge and coil domains, and its ATPase domain lacks conserved amino acids required for ATP hydrolysis, leading to the speculation that it may inhibit condensin ATPase activity. SMCL-1 homologs are apparent only in the subset of Caenorhabditis species in which the condensin I and II subunit SMC-4 duplicated to create the condensin IDC- specific subunit DPY-27, suggesting that SMCL-1 helps this lineage cope with the regulatory challenges imposed by evolution of a third condensin complex. Our findings uncover a new regulator of condensins and highlight how the duplication and divergence of SMC complex components in various lineages has created new proteins with diverse functions in chromosome dynamics.

PMID:
28301465
PMCID:
PMC5373644
DOI:
10.1371/journal.pgen.1006614
[Indexed for MEDLINE]
Free PMC Article

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