title: No evidence for a forced-unfolding mechanism during ATP/GroES binding to substrate-bound GroEL: no observable protection of metastable Rubisco intermediate or GroEL-bound Rubisco from tritium exchange.
abstract: In tritium-hydrogen exchange experiments, the large GroEL substrate Rubisco was unfolded and exchanged in urea/acid/tritiated water, then diluted into either protic buffer or protic buffer containing GroEL. The respective Rubisco metastable folding intermediate or Rubisco-GroEL binary complex was then separated from residual tritium after varying times of exchange by centrifugation through P-10 or G-25 resin. No significant tritium was recovered in either case, in contrast to an earlier report. Thus, although the earlier-proposed forced unfolding mechanism for the action of GroEL on a bound polypeptide, occurring during ATP/GroES binding, remains an attractive hypothesis, the data here do not provide any indication that it is involved in the folding of Rubisco.
authors.affiliation: Howard Hughes Medical Institute, Yale School of Medicine, Boyer Center, 295 Congress Avenue, New Haven, CT 06510, USA.
authors.forename: Eun Sun
authors.initials: ES
authors.lastname: Park
authors.forename: Wayne A
authors.initials: WA
authors.lastname: Fenton
authors.forename: Arthur L
authors.initials: AL
authors.lastname: Horwich
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D018835:Chaperonin 10 / Q000378:metabolism*; D018834:Chaperonin 60 / Q000378:metabolism*; D011489:Protein Denaturation; D017510:Protein Folding; D012247:Rhodospirillum rubrum / Q000378:metabolism*; D012273:Ribulose-Bisphosphate Carboxylase / Q000378:metabolism*; D014316:Tritium / Q000378:metabolism*
chemical_list: D018835:Chaperonin 10; D018834:Chaperonin 60; D014316:Tritium; D000255:Adenosine Triphosphate; D012273:Ribulose-Bisphosphate Carboxylase