The homeodomain transcription factor Pdx1 is essential for pancreatic
development, function, and maintenance. Mutations in pdx1 lead to impairments in beta
cell function, glucose tolerance, and insulin secretion that result in diabetic phenotypes.
Most clinically documented Pdx1 sequence variants map to disordered regions of the
protein whose function is not well-characterized. Our group has confirmed that the
disordered C-terminus of Pdx1 participates in essential regulatory interactions and that
mutations within this region disrupt binding.
The current work aims to elucidate mechanistic detail of the interaction of the Pdx1-
C terminal domain with the MATH domain of the E3 ubiquitin ligase adaptor SPOP. This
is achieved through the thermodynamic and structural characterization of the Pdx1-SPOP
complex, which reveals binding affinities and atomistic details describing the binding
event. The effects of multivalency have been assessed through calorimetric and
spectroscopic binding assays using minimal peptides encompassing individual Pdx1
binding sites. The results herein provide a molecular level understanding of this
interaction crucial to glucose homeostasis.
