Structure of -lytic protease complexed with its pro region
Nicholas K. Sauter1, Ted Mau1, 2, Stephen D. Rader2
& David A. Agard2
1
These authors contributed equally to this work. Howard
Hughes Medical Institute, San Francisco, San Francisco
, California 94143-0448, USA.
2
the Graduate Group in Biophysics and the Department
of Biochemistry and Biophysics, University of California, San Francisco
, San Francisco, California 94143-0448,
USA.
While the majority of proteins fold rapidly and spontaneously to their
native states, the extracellular bacterial protease -lytic protease
(LP) has a t1/2 for folding of ~2,000 years, corresponding
to a folding barrier of 30 kcal mol−1. LP is synthesized
as a pro-enzyme where its pro region (Pro) acts as a foldase to stabilize
the transition state for the folding reaction. Pro also functions as a potent
folding catalyst when supplied as a separate polypeptide chain, accelerating
the rate of LP folding by a factor of 3 109.
In the absence of Pro, LP folds only partially to a stable molten globule-like
intermediate state. Addition of Pro to this intermediate leads to rapid formation
of native LP. Here we report the crystal structures of Pro and of the
non-covalent inhibitory complex between Pro and native LP. The C-shaped
Pro surrounds the C-terminal -barrel domain of the folded protease,
forming a large complementary interface. Regions of extensive hydration in
the interface explain how Pro binds tightly to the native state, yet even
more tightly to the folding transition state. Based on structural and functional
data we propose that a specific structural element in LP is largely
responsible for the folding barrier and suggest how Pro can overcome this
barrier.
-lytic protease complexed with its pro region
-lytic protease
(
109.
In the absence of Pro, 
-barrel domain of the folded protease,
forming a large complementary interface. Regions of extensive hydration in
the interface explain how Pro binds tightly to the native state, yet even
more tightly to the folding transition state. Based on structural and functional
data we propose that a specific structural element in 
