There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.
Abstract
Small-angle neutron scattering and contrast variation were used to study the solution
structure of GroEL and GroEL/GroES chaperonins complexed with a nonnative variant
of the polypeptide substrate, subtilisin (PJ9). The subtilisin was 86% deuterated
(dPJ9) so that it contrasted sufficiently with the chaperonin, allowing the contrast
variation technique to be used to separate the scattering from the two components
bound in the complex. Both the native double-ring GroEL and a single-ring mutant were
used with dPJ9 bound in a 1:1 stoichiometry per GroEL toroid. This allowed both the
position and the shape of dPJ9 in the GroEL/dPJ9 complexes to be determined. A single-ring
GroEL/GroES variant complexed with one dPJ9 molecule was used to study the structural
changes of dPJ9 in GroEL/GroES/dPJ9 complexes formed with ADP and with ATP. It was
found that both the shape and the position of the bound dPJ9 in the GroEL/GroES/dPJ9
complex with ADP were the same as those in the GroEL/dPJ9 complex. However, dPJ9 assumed
a more symmetric shape when bound in the GroEL/GroES/dPJ9 complex with ATP. This important
observation reflects the relative ability of ATP to promote refolding of protein substrates
relative to that of ADP.