Chao, Lucy Fang-ISingh, MehaThompson, JamesYates, John R. 3rdHagstrom, Kirsten A.2022-08-232022-08-232017-03-162017-09-12PLoS Genet. 2017 Mar 16;13(3):e1006614. doi: 10.1371/journal.pgen.1006614. eCollection 2017 Mar. <a href="https://doi.org/10.1371/journal.pgen.1006614">Link to article on publisher's site</a>1553-7390 (Linking)10.1371/journal.pgen.100661428301465https://hdl.handle.net/20.500.14038/40314Structural 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.en-USCopyright: © 2017 Chao et al.http://creativecommons.org/licenses/by/4.0/BiochemistryGeneticsStructural BiologyJournal Articlehttps://escholarship.umassmed.edu/cgi/viewcontent.cgi?article=4121&amp;context=oapubs&amp;unstamped=1https://escholarship.umassmed.edu/oapubs/311510737546oapubs/3115