Structural and functional aspects of the interaction partners of the small heat-shock protein in Synechocystis

Erik G Marklund,Yichen Zhang,Elizabeth Vierling,Eman Basha,Justin L.P Benesch

doi:10.1007/s12192-018-0884-3

Abstract

The canonical function of small heat-shock proteins (sHSPs) is to interact with proteins destabilized under conditions of cellular stress. While the breadth of interactions made by many sHSPs is well-known, there is currently little knowledge about what structural features of the interactors form the basis for their recognition. Here, we have identified 83 in vivo interactors of the sole sHSP in the cyanobacterium Synechocystis sp. PCC 6803, HSP16.6, reflective of stable associations with soluble proteins made under heat-shock conditions. By performing bioinformatic analyses on these interactors, we identify primary and secondary structural elements that are enriched relative to expectations from the cyanobacterial genome. In addition, by examining the Synechocystis interactors and comparing them with those identified to bind sHSPs in other prokaryotes, we show that sHSPs associate with specific proteins and biological processes. Our data are therefore consistent with a picture of sHSPs being broadly specific molecular chaperones that act to protect multiple cellular pathways.

Highlights

IntroductionThe original version of this article was revised: Table 1 needed corrections
In order to investigate the properties of proteins that are sHSP interactors, we identified HSP16.6 from the singlecelled cyanobacterium Synechocystis sp
To identify a larger number of HSP16.6-associated proteins than we did previously (Basha et al 2004), we developed a Synechocystis strain in which the wild-type HSP16.6 gene was replaced with an HSP16.6 gene modified to encode a Strep-tag II at the C-terminus

Summary

Introduction

The original version of this article was revised: Table 1 needed corrections. SHSPs are relatively small as monomers (12 to 42 kDa), the majority assemble into large oligomers. These range in size from 12 to > 40 subunits, with some family members being monodisperse and others forming polydisperse ensembles (Basha et al 2012; Hilton et al 2013; McHaourab et al 2009). A major gap in our understanding of sHSP mechanism is the considerable lack of information about which substrates they protect in the cell

Methods

Results

Conclusion