Seminars Archive
Laura Spagnolo
Abstract
Tuesday, September 11, 2001, 14:00
Seminar Room, ground floor, Building "T"
Sincrotrone Trieste, Basovizza
Stabilizing SH3 hydrophobic core mutants
Laura Spagnolo
(Structural Biology and Biocomputing Programme, EMBL-Heidelberg,
Germany)
ABSTRACT
To understand protein evolution we need to know what are the structural
constraints, if any, that could prevent a particular sequence to explore
all the available sequence space compatible with a particular fold and
function. To find if this is the case, we used an automatic protein design
algorithm, Perla, to jump over barriers and explore core sequences not
found in nature. We have found that divergent core sequences not explored
by nature are compatible with the integrity and functionality of the _-spectrin
SH3 domain.
Since several of the designed core mutants were partly folded, a stabilizing
point mutation was made on them to increase their stability, in order to
study their structure, their folding properties and the tendency that these
mutants have towards amyloid fiber formation. We mutated D48G in the type
IIÃ _-turn of the SH3 distal loop. This mutation stabilizes significantly
the protein through a local conformational change of the turn.
The stabilized core mutants show very peculiar features. All of them
fold much faster than the core mutants without this stabilizing mutation.
For some of them, it was possible to determine the presence of a folding
intermediate; in several cases, fiber formation occurred; a group of mutants
shows properties which are typical of molten globules.
