New insights into the architecture of the human SMC5/6 complex

ABSTRACT: A family of Structural Maintenance of Chromosome (SMC) complexes is essential for key cellular processes ensuring proper cohesion, condensation and replication. They share common SMC-kleisin architecture allowing them to embrace DNA. The prokaryotic and eukaryotic SMC5/6 complexes contain additional kleisin-interacting KITE subunits which regulate SMC-kleisin dynamics. In SMC5/6, the Nse1 and Nse3 KITE proteins and Nse4 kleisin subunits form stable subcomplex which binds DNA and regulates essential processes. In addition, non-essential Nse5 and Nse6 subunits associate with the core SMC5/6 complex and recruit it to DNA repair sites. The architecture of the SMC5/6 complex is crucial for its proper functioning and mutations within the human SMC5/6 subunits result in severe syndromes. Therefore, we aimed to analyse interactions within the human SMC5/6 complex and determine its architecture at detail levels. First, we analysed the human hNSE1-hNSE3 dimer and the hNSE1-hNSE3-hNSE4 trimer by crosslinking and MS/MS analysis. Our data suggested domain arrangements of hNSE1-hNSE3 and orientation of hNSE4 within the trimer. The crosslinking and electron microscopy analysis of the SMC5/6 core complex showed its rod-like shaped architecture with juxtaposed hSMC5-hSMC6 arms. In addition, we observed fully or partially opened hSMC5-hSMC6 shapes with the hNSE1-hNSE3-hNSE4 trimer localized at the SMC head domains. To complete mapping of the human SMC5/6 complex architecture, we analysed positions of hNSE5-hNSE6 at the hSMC5-hSMC6 arms. Interestingly, hNSE6 bound both hSMC5-hSMC6 arms, suggesting that hNSE6 may lock the arms and regulate their dynamics. All together, we gained new insights into the architecture and dynamics of the human SMC5/6 complex.

INSTRUMENT(S): LTQ Orbitrap Elite

ORGANISM(S): Homo Sapiens (human)

SUBMITTER: David Potesil  

LAB HEAD: Zbynek Zdrahal

PROVIDER: PXD017379 | Pride | 2023-08-18

REPOSITORIES: Pride