Determinants of Rbp1p localization in specific cytoplasmic mRNA-processing foci, P-bodies.
Rbp1p, a yeast RNA-binding protein, decreases the level of mitochondrial porin mRNA by enhancing its degradation, but the intracellular location of the Rbp1p-mediated degradation complex remains unknown. We show here that Rbp1p in xrn1Delta mutant yeast localizes in specific cytoplasmic foci that are known as P-bodies. The N-terminal and RNA recognition motif (RRM) 1 domains of Rbp1p are necessary but not sufficient for its localization in P bodies. Rbp1p forms oligomers through its C-terminal domain in vivo; N-terminal-delete, or RRM1-mutated Rbp1p can be more efficiently recruited to P-bodies in an xrn1Delta strain, expressing a full-length Rbp1p. Although POR1 mRNA is localized to P bodies in an xrn1Delta strain, this localization does not depend on Rbp1p. Decapping activator Dhh1p directly interacts with Rbp1p. However, the recruitment of Rbp1p to P-bodies does not require Dhh1p or Ccr4p. In wild-type cells, Rbp1p can localize to P-bodies under glucose deprivation or treatment with KCl. In addition, Rbp1p-mediated porin mRNA decay is elicited by Xrn1p, a 5 ' to 3 ' exonuclease. These results provide new insight into the mechanism of Rbp1p function.
Jang
Li-Ting
LT
Institute of Molecular Medicine, School of Medicine, National Taiwan University and Department of Medical Research, National Taiwan University Hospital, Taipei, Taiwan.
Buu
Leh-Miauh
LM
Lee
Fang-Jen S
FJ
D003593:Cytoplasm / Q000378:metabolism*; D053487:DEAD-box RNA Helicases / Q000378:metabolism; D017353:Gene Deletion; D005838:Genotype; D008957:Models, Genetic; D009154:Mutation; D010957:Plasmids / Q000378:metabolism; D018272:Porins / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012313:RNA / Q000737:chemistry; D012333:RNA, Messenger / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000737:chemistry* / Q000502:physiology; D054398:Receptors, CCR4; D019707:Receptors, Chemokine / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000378:metabolism / Q000502:physiology
C082119:NGR1 protein, S cerevisiae; D018272:Porins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D054398:Receptors, CCR4; D019707:Receptors, Chemokine; D029701:Saccharomyces cerevisiae Proteins; D012313:RNA; C445083:DHH1 protein, S cerevisiae; D053487:DEAD-box RNA Helicases