GROEL/ES Buffers Entropic Traps in Folding Pathway during Evolution of a Model Substrate

• Published in: Journal of molecular biology 2020-09, Vol.432 (20), p.5649-5664
• Main Authors: Sadat, Anwar, Tiwari, Satyam, Verma, Kanika, Ray, Arjun, Ali, Mudassar, Upadhyay, Vaibhav, Singh, Anupam, Chaphalkar, Aseem, Ghosh, Asmita, Chakraborty, Rahul, Chakraborty, Kausik, Mapa, Koyeli
• Format: Article
• Language: English
• Subjects: Binding Sites; Chaperone; Chaperonin; Chaperonin 60 - chemistry; Chaperonin 60 - genetics; Chaperonin 60 - metabolism; Chaperonins; Escherichia coli - metabolism; Escherichia coli Proteins - chemistry; Escherichia coli Proteins - metabolism; Heat-Shock Proteins; Kinetic barriers; Kinetics; Molecular Chaperones - chemistry; Molecular Chaperones - genetics; Molecular Chaperones - metabolism; Mutation; Mutational buffering; Protein Folding
• ISSN: 0022-2836; 1089-8638
• DOI: 10.1016/j.jmb.2020.08.015

The folding landscape of proteins can change during evolution with the accumulation of mutations that may introduce entropic or enthalpic barriers in the protein folding pathway, making it a possible substrate of molecular chaperones in vivo. Can the nature of such physical barriers of folding dictate the feasibility of chaperone-assistance? To address this, we have simulated the evolutionary step to chaperone-dependence keeping GroEL/ES as the target chaperone and GFP as a model protein in an unbiased screen. We find that the mutation conferring GroEL/ES dependence in vivo and in vitro encode an entropic trap in the folding pathway rescued by the chaperonin. Additionally, GroEL/ES can edit the formation of non-native contacts similar to DnaK/J/E machinery. However, this capability is not utilized by the substrates in vivo. As a consequence, GroEL/ES caters to buffer mutations that predominantly cause entropic traps, despite possessing the capacity to edit both enthalpic and entropic traps in the folding pathway of the substrate protein. [Display omitted] •Made an expression-controlled GFP library to study chaperone-dependence in vivo.•Simulated a single step of molecular evolution toward GroEL/ES dependence in vivo.•GroEL/ES can prevent non-native contacts and take protein out of entropic traps.•The model substrate in vivo use GroEL/ES’ capacity to remove entropic traps.