Background: Protein folding mediated by a symmetric GroEL-(GroES) 2 complex is poorly understood. Results: Single-molecule imaging revealed that GFP folding proceeded in both rings of the symmetric GroEL-(GroES) 2 complex. Conclusion:The same reaction occurs independently in both rings of the symmetric GroEL-(GroES) 2 complex. Significance: The study provides insight into the mechanism of protein folding mediated by the symmetric GroEL-(GroES) 2 complex.

spatial distribution by binning mass speetrum, This bundle of mass spectrum corresponds to maximum likelihood estirnation and entropy image caleulated from bund]ed spectrum shows more distinct pattenn than norma] entropy image, 3PS029 Yodai Takei, Sci,, The Univ, The chaperonm protein fold commonly believed that GroES binds alternatively to each ring of GroEL, which is composed of two identjca] rings stacked back to back, during ihe functional cyc]e, ln other words, an asymmettic GroEL-GroES comp]ex (the bu]let-shaped complex) is formed throughout the cycle, whereas a symmetric GroEL-(GreES)2 complex (the football-shaped complex) is not formed. We have Tecent]y shown that the football-shaped complex coexists with the bulletshaped complex during the functional cyele. Hewever, how pTotein folding proceeds in the football-shaped comp]ex remains poorly understood, Here, we used green fluorescent protein (GFP) as a substrate to visua]ize the folding in the football-shaped cDmplex by single-motecule fiuorescence techniques. First, we directly counted the number of refolded GFP molecules in the football-shaped complex, and showed that GFP can fold in both rings ofthe complex. Next, we