title: Intracellular trafficking of guanylate-binding proteins is regulated by heterodimerization in a hierarchical manner.
abstract: Guanylate-binding proteins (GBPs) belong to the dynamin family of large GTPases and represent the major IFN-γ-induced proteins. Here we systematically investigated the mechanisms regulating the subcellular localization of GBPs. Three GBPs (GBP-1, GBP-2 and GBP-5) carry a C-terminal CaaX-prenylation signal, which is typical for small GTPases of the Ras family, and increases the membrane affinity of proteins. In this study, we demonstrated that GBP-1, GBP-2 and GBP-5 are prenylated in vivo and that prenylation is required for the membrane association of GBP-1, GBP-2 and GBP-5. Using co-immunoprecipitation, yeast-two-hybrid analysis and fluorescence complementation assays, we showed for the first time that GBPs are able to homodimerize in vivo and that the membrane association of GBPs is regulated by dimerization similarly to dynamin. Interestingly, GBPs could also heterodimerize. This resulted in hierarchical positioning effects on the intracellular localization of the proteins. Specifically, GBP-1 recruited GBP-5 and GBP-2 into its own cellular compartment and GBP-5 repositioned GBP-2. In addition, GBP-1, GBP-2 and GBP-5 were able to redirect non-prenylated GBPs to their compartment in a prenylation-dependent manner. Overall, these findings prove in vivo the ability of GBPs to dimerize, indicate that heterodimerization regulates sub-cellular localization of GBPs and underscore putative membrane-associated functions of this family of proteins.
authors.affiliation: Division of Molecular and Experimental Surgery, University Medical Center Erlangen, Friedrich-Alexander University of Erlangen-Nuremberg, Erlangen, Germany.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Britzen-Laurent
authors.forename: Michael
authors.initials: M
authors.lastname: Bauer
authors.forename: Valeria
authors.initials: V
authors.lastname: Berton
authors.forename: Nicole
authors.initials: N
authors.lastname: Fischer
authors.forename: Adrian
authors.initials: A
authors.lastname: Syguda
authors.forename: Simone
authors.initials: S
authors.lastname: Reipschläger
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Naschberger
authors.forename: Christian
authors.initials: C
authors.lastname: Herrmann
authors.forename: Michael
authors.initials: M
authors.lastname: Stürzl
mesh_terms: D020816:Amino Acid Motifs; D049109:Cell Proliferation; D019281:Dimerization; D005434:Flow Cytometry; D020558:GTP Phosphohydrolases / Q000737:chemistry; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006056:Golgi Apparatus / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D009154:Mutation; D021381:Protein Transport; D013347:Subcellular Fractions; D020798:Two-Hybrid System Techniques
chemical_list: D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins