Rewiring MAP Kinase Pathways Using Alternative Scaffold Assembly Mechanisms

Abstract

How scaffold proteins control information flow in signaling pathways is poorly understood: Do they simply tether components, or do they precisely orient and activate them? We found that the yeast mitogen-activated protein (MAP) kinase scaffold Ste5 is tolerant to major stereochemical perturbations; heterologous protein interactions could functionally replace native kinase recruitment interactions, indicating that simple tethering is largely sufficient for scaffold-mediated signaling. Moreover, by engineering a scaffold that tethers a unique kinase set, we could create a synthetic MAP kinase pathway with non-natural input-output properties. These findings demonstrate that scaffolds are highly flexible organizing factors that can facilitate pathway evolution and engineering.

Synthetic Multivalent Ligands as Probes of Signal Transduction

“…In the few examples studied to date, the localization of receptors to a signaling complex is often more important than their specific orientation within the complex. [233,236] Consistent with this view, the ability of dimeric ligands to activate signaling via ZAP-70 highlights that different RE orientations often give rise to only subtle effects. [107] ZAP-70 is a kinase whose function is required for the varied signaling functions of the T cell.…”

“…Interestingly, these findings are consistent with studies in which fusion proteins have been used to test whether different assemblies of signaling domains influence output. [233,236] As with the ZAP-70 investigations, the orientation of different signaling domains was much less important than their recruitment to a signaling complex. It will be interesting to explore further the generality of these findings.…”

Synthetic circuits, devices and modules

“…In S. cerevisiae, Ste5p is a well-characterized scaffold protein that tethers multiple protein kinases in the mitogen-activated protein (MAP) kinase cascade required for mating and Pbs2 is involved in osmo-regulatory pathway. By creating a chimera scaffold with Ste5 and Pbs2, Park et al have redesigned yeast mitogen-activated protein kinase (MAPK) pathways that were able to generate mating responses when stimulated with high salt (Park et al, 2003).…”

Compact integration factor methods in high spatial dimensions

“…To illustrate this approach, we first approximate the integrand (27) using a r − 1th order Lagrange polynomial at a set of interpolation points t n+1 , t n ,…, t n+2−r : (28) Then (12) becomes (29) A first order implicit approximation to (τ) of the form (30) leads to a first order implicit scheme (31) A second order implicit approximation to (τ), (32) leads to a second order implicit scheme (33) Like the implicit ETD methods based on the non-compact representation, the nonlinear function of U n+1 in the compact implicit ETD (33) is also multiplied by terms involving the approximated differential operators and their exponentials. This non-local coupling makes the implicit ETD method inefficient.…”

“…Scaffold usually binds dynamically to two or more consecutively-acting components of a signaling cascade. Experimental work suggests that scaffolds may promote signal transmission by tethering consecutively acting kinases near each other [31,32]. However, it has also been experimentally observed that some scaffold inhibit signaling when over-expressed [33][34][35].…”