The NUG1 GTPase reveals and N-terminal RNA-binding domain that is essential for association with 60 S pre-ribosomal particles.
The putative yeast GTPase Nug1, which is associated with several pre-60 S particles in the nucleolus and nucleoplasm, consists of an N-terminal domain, which is found only in eukaryotic orthologues, and middle and C-terminal domains that are conserved throughout eukaryotes, bacteria, and archaea. Here, we analyzed the role of the eukaryote-specific Nug1 N-domain (Nug1-N). We show that the essential Nug1-N is sufficient and necessary for nucle(ol)ar targeting and association with pre-60 S particles. Nug1-N exhibits RNA binding activity and is genetically linked in an allele-specific way to the pre-60 S factors Noc2, Noc3, and Dbp10. In contrast, the middle domain, which exhibits a circularly permuted GTPase fold and an intrinsic GTP hydrolysis activity in vitro, is not essential for cell growth. The conserved Nug1 C-domain, which has a yet uncharacterized fold, is also essential for ribosome biogenesis. Our findings suggest that Nug1 associates with pre-60 S subunits via its essential N-terminal RNA-binding domain and exerts a non-essential regulative role in pre-60 S subunit biogenesis via its central GTPase domain.
Bassler
Jochen
J
Biochemie-Zentrum der Universität Heidelberg, 69120 Heidelberg, Germany.
Kallas
Martina
M
Hurt
Ed
E
D001665:Binding Sites; D002352:Carrier Proteins / Q000378:metabolism*; D053487:DEAD-box RNA Helicases; D004926:Escherichia coli; D020558:GTP Phosphohydrolases / Q000737:chemistry* / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism*; D029543:Nucleocytoplasmic Transport Proteins / Q000378:metabolism*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012313:RNA / Q000378:metabolism; D020365:RNA Helicases / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism; D012269:Ribosomal Proteins / Q000737:chemistry / Q000378:metabolism; D012270:Ribosomes / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000378:metabolism*
D002352:Carrier Proteins; C429647:NOC2 protein, S cerevisiae; C429648:NOC3 protein, S cerevisiae; D009687:Nuclear Proteins; D029543:Nucleocytoplasmic Transport Proteins; D016601:RNA-Binding Proteins; D012269:Ribosomal Proteins; D029701:Saccharomyces cerevisiae Proteins; D012313:RNA; C411109:DBP10 protein, S cerevisiae; D020558:GTP Phosphohydrolases; C437988:Nug1 protein, S cerevisiae; D053487:DEAD-box RNA Helicases; D020365:RNA Helicases