Article thumbnail

Identification of an Amphipathic Helix Important for the Formation of Ectopic Septin Spirals and Axial Budding in Yeast Axial Landmark Protein Bud3p

By Jia Guo, Ting Gong and Xiang-Dong Gao


Correct positioning of polarity axis in response to internal or external cues is central to cellular morphogenesis and cell fate determination. In the budding yeast Saccharomyces cerevisiae, Bud3p plays a key role in the axial bud-site selection (axial budding) process in which cells assemble the new bud next to the preceding cell division site. Bud3p is thought to act as a component of a spatial landmark. However, it is not clear how Bud3p interacts with other components of the landmark, such as the septins, to control axial budding. Here, we report that overexpression of Bud3p causes the formation of small septin rings (∼1 µm in diameter) and arcs aside from previously reported spiral-like septin structures. Bud3p closely associates with the septins in vivo as Bud3p colocalizes with these aberrant septin structures and forms a complex with two septins, Cdc10p and Cdc11p. The interaction of Bud3p with the septins may involve multiple regions of Bud3p including 1–858, 850–1220, and 1221–1636 a.a. since they all target to the bud neck but exhibit different effects on septin organization when overexpressed. In addition, our study reveals that the axial budding function of Bud3p is mediated by the N-terminal region 1–858. This region shares an amphipathic helix (850–858) crucial for bud neck targeting with the middle portion 850–1103 involved in the formation of ectopic septin spirals and rings. Interestingly, the Dbl-homology domain located in 1–858 is dispensable for axial bud-site selection. Our findings suggest that multiple regions of Bud3p ensure efficient targeting of Bud3p to the bud neck in the assembly of the axial landmark and distinct domains of Bud3p are involved in axial bud-site selection and other cellular processes

Topics: Research Article
Publisher: Public Library of Science
OAI identifier:
Provided by: PubMed Central

To submit an update or takedown request for this paper, please submit an Update/Correction/Removal Request.

Suggested articles


  1. (2003). A Bni4-Glc7 phosphatase complex that recruits chitin synthase to the site of bud emergence.
  2. (2005). A membrane binding domain in the Ste5 scaffold synergizes with Gbc binding to control localization and signaling in pheromone response.
  3. (1997). A septin-based hierarchy of proteins required for localized deposition of chitin in the Saccharomyces cerevisiae cell wall.
  4. (1994). A yeast gene necessary for bud-site selection encodes a protein similar to insulin-degrading enzymes.
  5. (2003). Adaptation of core mechanisms to generate cell polarity.
  6. (1998). Additional modules for versatile and economical PCR-based gene deletion and modification in Saccharomyces cerevisiae.
  7. (2003). Analysis of the landmark protein Bud3 of Ashbya gossypii reveals a novel role in septum construction.
  8. (1996). Bud10p directs axial cell polarization in budding yeast and resembles a transmembrane receptor.
  9. (2001). Bud8p and Bud9p, proteins that may mark the sites for bipolar budding in yeast.
  10. (2001). Candida albicans Int1p interacts with the septin ring in yeast and hyphal cells.
  11. (2000). Cell cycle programs of gene expression control morphogenetic protein localization.
  12. (1993). Components required for cytokinesis are important for bud site selection in yeast.
  13. (2003). Differential cellular localization among mitotic cyclins from Saccharomyces cerevisiae: a new role for the axial budding protein
  14. (1995). Establishment of cell polarity in yeast.
  15. (1997). Extracting protein alignment models from the sequence database.
  16. (2004). Functional interdependence between septin and actin cytoskeleton.
  17. (1991). Guide to Yeast Genetics and Molecular Biology. San DiegoCA:
  18. (2007). Identification of novel membrane-binding domains in multiple yeast Cdc42 effectors.
  19. (2004). Interactions among Rax1p, Rax2p, Bud8p, and Bud9p in marking cortical sites for bipolar bud-site selection in yeast.
  20. (2005). Interplay between septin organization, cell cycle and cell shape in yeast.
  21. (2003). Membrane binding by MinD involves insertion of hydrophobic residues within the C-terminal amphipathic helix into the bilayer.
  22. (2002). Membrane localization of MinD is mediated by a C-terminal motif that is conserved across eubacteria, archaea, and chloroplasts.
  23. (2000). Multigenerational cortical inheritance of the Rax2 protein in orienting polarity and division in yeast.
  24. (1997). N-terminal hydrophobic residues of the G-protein ADP-ribosylation factor-1 insert into membrane phospholipids upon GDP to GTP exchange.
  25. (1996). Origins of cell polarity.
  26. (2004). Paoletti A
  27. (2004). Protein-protein interactions governing septin heteropentamer assembly and septin filament organization in Saccharomyces cerevisiae.
  28. (2004). Rax1, a protein required for the establishment of the bipolar budding pattern in yeast.
  29. (2000). Regulation of cytokinesis by the Elm1 protein kinase in Saccharomyces cerevisiae.
  30. (2009). Regulation of distinct septin rings in a single cell by Elm1p and Gin4p kinases.
  31. (2008). Regulation of Gic2 localization and function by phosphatidylinositol 4,5-bisphosphate during the establishment of cell polarity in budding yeast.
  32. (2010). Regulation of septum formation by the Bud3-Rho4 GTPase module in Aspergillus nidulans.
  33. (2000). RGS4 binds to membranes through an amphipathic alpha-helix.
  34. (1995). Role of Bud3p in producing the axial budding pattern of yeast.
  35. (1996). Selection of axial growth sites in yeast requires Axl2p, a novel plasma membrane glycoprotein.
  36. (2002). Selfand actin-templated assembly of mammalian septins.
  37. (2010). Septum formation is regulated by the RHO4-specific exchange factors BUD3 and RGF3 and by the landmark protein BUD4 in Neurospora crassa.
  38. (2007). Sequential and distinct roles of the cadherin domain-containing protein Axl2p in cell polarization in yeast cell cycle.
  39. (2002). Subcellular localization of Axl1, the cell type-specific regulator of polarity.
  40. (1996). The Bud4 protein of yeast, required for axial budding, is localized to the mother/bud neck in a cell cycle-dependent manner.
  41. (2003). The role of Cdc42p GTPaseactivating proteins in assembly of the septin ring in yeast.
  42. (2002). The roles of bud-site-selection proteins during haploid invasive growth in yeast.