0:04
I'm going to review how folding
occurs in an
encapsulated chamber
and I'll discuss how the nucleotide cycle is
used to drive the GroEL and GroES chaperonin and
machine forward through
its reaction cycle.
Finally, I'll present a
summarizing movie that
essentially connects
all the dots of
X-ray structures and EM
structural information
to give us a working, coherent picture
of how the reaction cycle works.
0:35
Now, I want to talk about
the folding reaction
mediated by the
GroEL/GroES system, and
here, ongoing collaborations
with Helen Saibil have
been critical to our
understanding of this system.
0:51
When we initially looked
at one of our
favorite substrates,
rhodanese taking the model
for its native state
and imposing on the
apical domains of GroEL,
while associated with GroEL.
We noticed that there's
a terrible steric clash
between rhodanese and
the apical domains.
This suggested that
there was no way
that rhodanese
could productively
reach the native state
inside of unliganded GroEL.
But, Helen changed our thinking
about how folding could occur.
1:21
What she observed was that
when GroES binds to GroEL,
the side of GroEL to which
GroES associates opens up,
that is the apical domains
open up and a chamber is
produced in which
one could envision
that potentially a
polypeptide could fold.
By contrast, if you look
at the opposite ring,
which is not bound by GroES,
it occupies a relatively
closed state,
which is consistent with
the 45 Angstrom
diameter open ring.
Here on the GroES-bound side,
things have opened
up considerably.
