1. Chemistry and Chemical Biology Graduate Program, University of California, San Francisco, San Francisco, California 94158-2517, USA
2. Department of Cellular and Molecular Pharmacology and the Cell Propulsion Lab, UCSF/UCB NIH Nanomedicine Development Center, University of California, San Francisco, San Francisco, California 94158-2517, USA
3. Department of Molecular Genetics and Microbiology, School of Medicine, State University of New York at Stony Brook, Stony Brook, New York 11794, USA
4. Department of Biochemistry, New York University School of Medicine, New York, New York 10016, USA
5. These authors contributed equally to this work.

Correspondence to: Dafna Bar-Sagi^3,4Wendell A. Lim² Correspondence and requests for materials should be addressed to W.A.L. (Email: lim@cmp.ucsf.edu) or D.B.-S. (Email: dafna.bar-sagi@med.nyu.edu).

Eukaryotic cells mobilize the actin cytoskeleton to generate a remarkable diversity of morphological behaviours, including motility, phagocytosis and cytokinesis. Much of this diversity is mediated by guanine nucleotide exchange factors (GEFs) that activate Rho family GTPases—the master regulators of the actin cytoskeleton^{1, 2, 3}. There are over 80 Rho GEFs in the human genome (compared to only 22 genes for the Rho GTPases themselves), and the evolution of new and diverse GEFs is thought to provide a mechanism for linking the core cytoskeletal machinery to a wide range of new control inputs. Here we test this hypothesis and ask if we can systematically reprogramme cellular morphology by engineering synthetic GEF proteins. We focused on Dbl family Rho GEFs, which have a highly modular structure common to many signalling proteins^{4, 5}: they contain a catalytic Dbl homology (DH) domain linked to diverse regulatory domains, many of which autoinhibit GEF activity^{2, 3}. Here we show that by recombining catalytic GEF domains with new regulatory modules, we can generate synthetic GEFs that are activated by non-native inputs. We have used these synthetic GEFs to reprogramme cellular behaviour in diverse ways. The GEFs can be used to link specific cytoskeletal responses to normally unrelated upstream signalling pathways. In addition, multiple synthetic GEFs can be linked as components in series to form an artificial cascade with improved signal processing behaviour. These results show the high degree of evolutionary plasticity of this important family of modular signalling proteins, and indicate that it may be possible to use synthetic biology approaches to manipulate the complex spatio-temporal control of cell morphology.

MORE ARTICLES LIKE THIS

These links to content published by NPG are automatically generated.