RRC ID 25696
Author Yu Y, Li C, Kita A, Katayama Y, Kubouchi K, Udo M, Imanaka Y, Ueda S, Masuko T, Sugiura R.
Title Sip1, an AP-1 accessory protein in fission yeast, is required for localization of Rho3 GTPase.
Journal PLoS ONE
Abstract Rho family GTPases act as molecular switches to regulate a range of physiological functions, including the regulation of the actin-based cytoskeleton, membrane trafficking, cell morphology, nuclear gene expression, and cell growth. Rho function is regulated by its ability to bind GTP and by its localization. We previously demonstrated functional and physical interactions between Rho3 and the clathrin-associated adaptor protein-1 (AP-1) complex, which revealed a role of Rho3 in regulating Golgi/endosomal trafficking in fission yeast. Sip1, a conserved AP-1 accessory protein, recruits the AP-1 complex to the Golgi/endosomes through physical interaction. In this study, we showed that Sip1 is required for Rho3 localization. First, overexpression of rho3⁺ suppressed defective membrane trafficking associated with sip1-i4 mutant cells, including defects in vacuolar fusion, Golgi/endosomal trafficking and secretion. Notably, Sip1 interacted with Rho3, and GFP-Rho3, similar to Apm1-GFP, did not properly localize to the Golgi/endosomes in sip1-i4 mutant cells at 27°C. Interestingly, the C-terminal region of Sip1 is required for its localization to the Golgi/endosomes, because Sip1-i4-GFP protein failed to properly localize to Golgi/endosomes, whereas the fluorescence of Sip1ΔN mutant protein co-localized with that of FM4-64. Consistently, in the sip1-i4 mutant cells, which lack the C-terminal region of Sip1, binding between Apm1 and Rho3 was greatly impaired, presumably due to mislocalization of these proteins in the sip1-i4 mutant cells. Furthermore, the interaction between Apm1 and Rho3 as well as Rho3 localization to the Golgi/endosomes were significantly rescued in sip1-i4 mutant cells by the expression of Sip1ΔN. Taken together, these results suggest that Sip1 recruits Rho3 to the Golgi/endosomes through physical interaction and enhances the formation of the Golgi/endosome AP-1/Rho3 complex, thereby promoting crosstalk between AP-1 and Rho3 in the regulation of Golgi/endosomal trafficking in fission yeast.
Volume 8(7)
Pages e68488
Published 2013
DOI 10.1371/journal.pone.0068488
PII PONE-D-13-02957
PMID 23840894
PMC PMC3698097
MeSH Adaptor Protein Complex 1 / analysis Adaptor Protein Complex 1 / metabolism* Adaptor Proteins, Signal Transducing / analysis Adaptor Proteins, Signal Transducing / genetics Adaptor Proteins, Signal Transducing / metabolism* Endosomes / metabolism Golgi Apparatus / metabolism Mutation Protein Interaction Maps Protein Transport Schizosaccharomyces / cytology Schizosaccharomyces / genetics Schizosaccharomyces / metabolism* Schizosaccharomyces pombe Proteins / analysis Schizosaccharomyces pombe Proteins / genetics Schizosaccharomyces pombe Proteins / metabolism* Signal Transduction rho GTP-Binding Proteins / metabolism*
IF 2.776
Times Cited 2
Yeast SpENT18D04(SPAC23C4.08)