title: Probing the transient interaction between the small heat-shock protein Hsp21 and a model substrate protein using crosslinking mass spectrometry.
abstract: Small heat-shock protein chaperones are important players in the protein quality control system of the cell, because they can immediately respond to partially unfolded proteins, thereby protecting the cell from harmful aggregates. The small heat-shock proteins can form large polydisperse oligomers that are exceptionally dynamic, which is implicated in their function of protecting substrate proteins from aggregation. Yet the mechanism of substrate recognition remains poorly understood, and little is known about what parts of the small heat-shock proteins interact with substrates and what parts of a partially unfolded substrate protein interact with the small heat-shock proteins. The transient nature of the interactions that prevent substrate aggregation rationalize probing this interaction by crosslinking mass spectrometry. Here, we used a workflow with lysine-specific crosslinking and offline nano-liquid chromatography matrix-assisted laser desorption/ionization tandem time-of-flight mass spectrometry to explore the interaction between the plant small heat-shock protein Hsp21 and a thermosensitive model substrate protein, malate dehydrogenase. The identified crosslinks point at an interaction between the disordered N-terminal region of Hsp21 and the C-terminal presumably unfolding part of the substrate protein.
authors.affiliation: Department of Biochemistry and Structural Biology, Center for Molecular Protein Science, Institute for Chemistry and Chemical Engineering, Lund University, P.O. Box 124, SE-221 00, Lund, Sweden.
authors.forename: Wietske
authors.initials: W
authors.lastname: Lambert
authors.forename: Gudrun
authors.initials: G
authors.lastname: Rutsdottir
authors.forename: Rasha
authors.initials: R
authors.lastname: Hussein
authors.forename: Katja
authors.initials: K
authors.lastname: Bernfur
authors.forename: Sven
authors.initials: S
authors.lastname: Kjellström
authors.forename: Cecilia
authors.initials: C
authors.lastname: Emanuelsson
mesh_terms: D017360:Arabidopsis / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D003432:Cross-Linking Reagents / Q000737:chemistry*; D006360:Heat-Shock Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008291:Malate Dehydrogenase / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D029681:Arabidopsis Proteins; D003432:Cross-Linking Reagents; C400143:HSP21 protein, Arabidopsis; D006360:Heat-Shock Proteins; D010940:Plant Proteins; D011994:Recombinant Proteins; D008291:Malate Dehydrogenase