An asymmetric SMC-kleisin bridge in prokaryotic condensin

Prokaryotic condensins usually comprise an SMC homodimer, kleisin ScpA and ScpB. Structural and functional analyses of Bacillus subtilis condesin reveal an asymmetric bridge in which the termini of ScpA bind to distinct regions in each of the two SMC monomers. The findings suggest that the basic architecture for the tripartite condensin ring evolved before the emergence of eukaryotes.