title: Characterization of the heterotrimeric G-protein complex and its regulator from the green alga Chara braunii expands the evolutionary breadth of plant G-protein signaling.
abstract: The lack of heterotrimeric G-protein homologs in the sequenced genomes of green algae has led to the hypothesis that, in plants, this signaling mechanism coevolved with the embryophytic life cycle and the acquisition of terrestrial habitat. Given the large evolutionary gap that exists between the chlorophyte green algae and most basal land plants, the bryophytes, we evaluated the presence of this signaling complex in a charophyte green alga, Chara braunii, proposed to be the closest living relative of land plants. The C. braunii genome encodes for the entire G-protein complex, the Gα, Gβ, and Gγ subunits, and the REGULATOR OF G-PROTEIN SIGNALING (RGS) protein. The biochemical properties of these proteins and their cross-species functionality show that they are functional homologs of canonical G-proteins. The subunit-specific interactions between CbGα and CbGβ, CbGβ and CbGγ, and CbGα and CbRGS are also conserved, establishing the existence of functional G-protein complex-based signaling mechanisms in green algae.
authors.affiliation: Donald Danforth Plant Science Center, St. Louis, Missouri 63132.
authors.forename: Dieter
authors.initials: D
authors.lastname: Hackenberg
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Sakayama
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Nishiyama
authors.forename: Sona
authors.initials: S
authors.lastname: Pandey
mesh_terms: D000595:Amino Acid Sequence; D001681:Biological Assay; D005075:Biological Evolution; D044784:Chara / Q000235:genetics / Q000378:metabolism*; D017124:Conserved Sequence; D018506:Gene Expression Regulation, Plant; D018745:Genome, Plant / Q000235:genetics; D006160:Guanosine Triphosphate / Q000378:metabolism; D020962:Heterotrimeric GTP-Binding Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D021122:Protein Subunits / Q000378:metabolism; D020710:RGS Proteins / Q000378:metabolism; D015398:Signal Transduction; D014158:Transcription, Genetic
chemical_list: D010940:Plant Proteins; D021122:Protein Subunits; D020710:RGS Proteins; D006160:Guanosine Triphosphate; D020962:Heterotrimeric GTP-Binding Proteins