ATPase-dependent auto-phosphorylation of the open condensin hinge diminishes DNA binding.

Yuko Akai,Ryuta Kanai,Chikashi Toyoshima,Mitsuhiro Yanagida,Norihiko Nakazawa,Masahiro Ebe

doi:10.1098/rsob.140193

Abstract

Condensin, which contains two structural maintenance of chromosome (SMC) subunits and three regulatory non-SMC subunits, is essential for many chromosomal functions, including mitotic chromosome condensation and segregation. The ATPase domain of the SMC subunit comprises two termini connected by a long helical domain that is interrupted by a central hinge. The role of the ATPase domain has remained elusive. Here we report that the condensin SMC subunit of the fission yeast Schizosaccharomyces pombe is phosphorylated in a manner that requires the presence of the intact SMC ATPase Walker motif. Principal phosphorylation sites reside in the conserved, glycine-rich stretch at the hinge interface surrounded by the highly basic DNA-binding patch. Phosphorylation reduces affinity for DNA. Consistently, phosphomimetic mutants produce severe mitotic phenotypes. Structural evidence suggests that prior opening (though slight) of the hinge is necessary for phosphorylation, which is implicated in condensin's dissociation from and its progression along DNA.

Highlights

The condensin complex contains five distinct subunits, two structural maintenance of chromosome (SMC) subunits, denominated SMC2 and SMC4, and three non-SMC subunits
We discovered that the phosphate groups of ATP bind to multiple sites on Cut3, an SMC4-like subunit, but this apparent ‘auto-phosphorylation’ is greatly diminished when the holocondensin complex, which has ample ATPase activity, is employed
We show that multiple phosphorylation sites are located in the hinge of Cut3/SMC4, and that phosphorylation is abolished in ATPase mutants

Summary

Introduction

The condensin complex contains five distinct subunits, two structural maintenance of chromosome (SMC) subunits, denominated SMC2 and SMC4 (reviewed in [1,2]), and three non-SMC subunits. A number of studies have established that the role of condensin is highly conserved among diverse organisms from bacteria to humans (reviewed in [3]). Segregation, gene dosage compensation, DNA damage repair and transcriptional control [4,5,6,7,8,9]. Kimura & Hirano [10] showed that ATP-dependent positive supercoiling of DNA is induced by condensin. Sutani & Yanagida [11] demonstrated that the condensin SMC complex promotes DNA supercoiling and implicated it in chromosome condensation

Methods

Results

Discussion

Conclusion