Journal: PLoS ONE

Article Title: Plasmodium falciparum Hop (PfHop) Interacts with the Hsp70 Chaperone in a Nucleotide-Dependent Fashion and Exhibits Ligand Selectivity

doi: 10.1371/journal.pone.0135326

Figure Lengend Snippet: To further validate the interaction between PfHop and PfHsp70-1, SPR analysis was conducted with PfHop and PfHsp70-1 alternated as ligand and analyte, respectively. Full length PfHsp70-1 (1 μg/mL) was immobilised on the GLC sensor chip and variable concentrations of PfHop (2 μM, 1 μM, 0.5 μM, 0.25 μM, 0.125 μM) were passed over the immobilised chaperone. The assay was repeated using the ATPase subdomain of PfHsp70-1 (PfHsp70-1 NBD ) as a negative control. The sensograms represent data from at least three independent assays conducted in the presence of 5 mM ATP (panel A), 5mM ADP (panel B) and absence of nucleotides (panel C). The rate constants k a , k d and K D values of PfHop towards PfHsp70-1, and PfHop self-association were determined . The relative affinities of PfHop towards PfHsp70-1 and PfHop self-association were determined and presented as bar graphs (panel D). The relative affinities were normalized to PfHop interaction with PfHsp70-1in the absence of nucleotides (NN). Error bars obtained from the t-tests are indicated. We observed no significant difference in the association of PfHop with PfHsp70-1 in the presence of ADP and absence of nucleotide (*), ( p<0 . 005 ). However, affinity for the interaction between PfHop and PfHsp70-1 in the presence of ATP was significantly lower than observed in the absence of nucleotide/presence of ADP (**), ( p<0 . 005 ).

Article Snippet: Surface plasmon resonance (SPR) analysis was performed using a ProteOn XPR36 Interaction Array System with a GLC sensor chip (Biorad, USA).

Techniques: Negative Control