Saccharomyces cerevisiae Rbg1 Protein and Its Binding Partner Gir2 Interact on Polyribosomes with Gcn1

Abstract

Rbg1 is a previously uncharacterized protein of Saccharomyces cerevisiae belonging to the Obg/CgtA subfamily of GTP-binding proteins whose members are involved in ribosome function in both prokaryotes and eukaryotes. We show here that Rbg1 specifically associates with translating ribosomes. In addition, in this study proteins were identified that interact with Rbg1 by yeast two-hybrid screening and include Tma46, Ygr250c, Yap1, and Gir2. Gir2 contains a GI (Gcn2 and Impact) domain similar to that of Gcn2, an essential factor of the general amino acid control pathway required for overcoming amino acid shortage. Interestingly, we found that Gir2, like Gcn2, interacts with Gcn1 through its GI domain, and overexpression of Gir2, under conditions mimicking amino acid starvation, resulted in inhibition of growth that could be reversed by Gcn2 co-overexpression. Moreover, we found that Gir2 also cofractionated with polyribosomes, and this fractionation pattern was partially dependent on the presence of Gcn1. Based on these findings, we conclude that Rbg1 and its interacting partner Gir2 associate with ribosomes, and their possible biological roles are discussed.

Ubiquitin Ligase Trapping Identifies an SCFSaf1 Pathway Targeting Unprocessed Vacuolar/Lysosomal Proteins

“…Despite this, we were able to discern several strongly enriched candidates, many of which had roles in translation. The strongest of these, the polysome-associated Rbg1 protein, is a member of the Obg/CgtA GTP-binding proteins conserved from bacteria to humans (Wout et al, 2009). Although Rbg1 levels were not affected in ufo1 Δ strains (Figure 5C), ubiquitinated Rbg1 purified with two forms of the Ufo1 Trap, but not the Grr1-Fl-Rad23 control (Figure 5D).…”

“…Rps2 is a component of the small ribosomal subunit. Rbg1 and the elongation factor Yef3 are both components of polysomes (Fleischer et al, 2006; Hutchison et al, 1984; Wout et al, 2009). Rbg1 is conserved from E. coli to humans and, in bacteria, has been shown to be involved in the regulation of translation in response to nutrient deprivation (Wout et al, 2009).…”

“…Rbg1 and the elongation factor Yef3 are both components of polysomes (Fleischer et al, 2006; Hutchison et al, 1984; Wout et al, 2009). Rbg1 is conserved from E. coli to humans and, in bacteria, has been shown to be involved in the regulation of translation in response to nutrient deprivation (Wout et al, 2009). Moreover, a human homolog of Rbg1 (Drg2) undergoes SCF-mediated turnover (Chen et al, 2012), suggesting that this regulation is conserved.…”

Elevated ZC3H15 increases HCC growth and predicts poor survival after surgical resection

“…ZC3H15 also contains a characteristic tandem repeat CCCH zinc finger domain (TZF) with significant similarity to RNA-binding proteins [14], suggesting ZC3H15 function is linked to RNA metabolism. Moreover, recent observations suggest the yeast orthologs of DRG1, ZC3H15, and DFRP2 physically associate with active translation machinery [15, 16]. …”

Rbg1–Tma46 dimer structure reveals new functional domains and their role in polysome recruitment

“…The yeast Drg1 homolog is named Ribosome-binding GTPase 1 (Rbg1) as it was found associated to ribosome (18,19). It associates with yeast Dfrp1, namely Tma46, which is also a ribosome-associated protein (15,18).…”