Structural And Functional Characterization Of The Chaperone Hsp70 From Sugarcane. Insights Into Conformational Changes During Cycling From Cross-linking/mass Spectrometry Assays

Hsp70 cycles from an ATP-bound state, in which the affinity for unfolded polypeptides is low, to an ADP-bound state, in which the affinity for unfolded polypeptides is high, to assist with cell proteostasis. Such cycling also depends on co-chaperones because these proteins control both the Hsp70 ATPase activity and the delivery of unfolded polypeptide chains. Although it is very important, structural information on the entire protein is still scarce. This work describes the first cloning of a cDNA predicted to code for a cytosolic Saccharum spp. (sugarcane) Hsp70, named SsHsp70 here, the purification of the recombinant protein and the characterization of its structural conformation in solution by chemical cross-linking coupled to mass spectrometry. The in vivo expression of SsHsp70 in sugarcane extracts was confirmed by Western blot. 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