The third pdz domain from the synaptic protein psd-95 (h372a mutant) in complex with a mutant c-terminal peptide derived from cript (t-2f)
Structure:
Disks large homolog 4. Chain: a. Fragment: pdz-3 domain (unp residues 302-402). Synonym: postsynaptic density protein 95,psd-95,synapse-associated protein 90,sap90. Engineered: yes. Mutation: yes. Cysteine-rich pdz-binding protein. Chain: b.
A.S.Raman
et al.
(2016).
Origins of Allostery and Evolvability in Proteins: A Case Study.
Cell,
166,
468-480.
PubMed id: 27321669
DOI: 10.1016/j.cell.2016.05.047
Origins of Allostery and Evolvability in Proteins: A Case Study.
A.S.Raman,
K.I.White,
R.Ranganathan.
ABSTRACT
Proteins display the capacity for adaptation to new functions, a property
critical for evolvability. But what structural principles underlie the capacity
for adaptation? Here, we show that adaptation to a physiologically distinct
class of ligand specificity in a PSD95, DLG1, ZO-1 (PDZ) domain preferentially
occurs through class-bridging intermediate mutations located distant from the
ligand-binding site. These mutations provide a functional link between ligand
classes and demonstrate the principle of "conditional neutrality" in
mediating evolutionary adaptation. Structures show that class-bridging mutations
work allosterically to open up conformational plasticity at the active site,
permitting novel functions while retaining existing function. More generally,
the class-bridging phenotype arises from mutations in an evolutionarily
conserved network of coevolving amino acids in the PDZ family (the sector) that
connects the active site to distant surface sites. These findings introduce the
concept that allostery in proteins could have its origins not in protein
function but in the capacity to adapt.