Yeast Mn²⁺ Transporter, Smf1p, Is Regulated by Ubiquitin-Dependent Vacuolar Protein Sorting

Corresponding author: Stephen Garrett, UMDNJ-New Jersey Medical School, ICPH Bldg., 225 Warren St., P.O. Box 1709, Newark, NJ 07101-1709., garretst{at}umdnj.edu (E-mail)

Communicating editor: B. J. ANDREWS

Conditional cdc1(Ts) mutants of S. cerevisiae arrest with a phenotype similar to that exhibited by Mn²⁺-depleted cells. Sequence similarity between Cdc1p and a class of Mn²⁺-dependent phosphoesterases, as well as the observation that conditional cdc1(Ts) growth can be ameliorated by Mn²⁺ supplement, suggests that Cdc1p activity is sensitive to intracellular Mn²⁺ levels. This article identifies several previously uncharacterized cdc1(Ts) suppressors as class E vps (vacuolar protein sorting) mutants and shows that these, as well as other vps mutants, accumulate high levels of intracellular Mn²⁺. Yeast VPS genes play a role in delivery of membrane transporters to the vacuole for degradation, and we show that the vps mutants accumulate elevated levels of the high-affinity Mn²⁺ transporter Smf1p. cdc1(Ts) conditional growth is also alleviated by mutations, including doa4 and ubc4, that compromise protein ubiquitination, and these ubiquitination defects are associated with Smf1p accumulation. Epistasis studies show that these suppressors require functional Smf1p to alleviate the cdc1(Ts) growth defect, whereas Smf1p is dispensable for cdc1(Ts) suppression by a mutation (cos16/per1) that does not influence intracellular Mn²⁺ levels. Because Smf1p is ubiquitinated in vivo, we propose that Smf1p is targeted to the vacuole for degradation by ubiquitination-dependent protein sorting.

This article has been cited by other articles:

				E. Losev, E. Papanikou, O. W. Rossanese, and B. S. Glick Cdc1p Is an Endoplasmic Reticulum-Localized Putative Lipid Phosphatase That Affects Golgi Inheritance and Actin Polarization by Activating Ca2+ Signaling Mol. Cell. Biol., May 15, 2008; 28(10): 3336 - 3343. [Abstract] [Full Text] [PDF]

				S. P. Bai, L. Lu, X. G. Luo, and B. Liu Cloning, Sequencing, Characterization, and Expressions of Divalent Metal Transporter One in the Small Intestine of Broilers Poult. Sci., April 1, 2008; 87(4): 768 - 776. [Abstract] [Full Text] [PDF]

				J. A. Sullivan, M. J. Lewis, E. Nikko, and H. R.B. Pelham Multiple Interactions Drive Adaptor-Mediated Recruitment of the Ubiquitin Ligase Rsp5 to Membrane Proteins In Vivo and In Vitro Mol. Biol. Cell, July 1, 2007; 18(7): 2429 - 2440. [Abstract] [Full Text] [PDF]

				Y. Kim, Y. Deng, and C. C. Philpott GGA2- and Ubiquitin-dependent Trafficking of Arn1, the Ferrichrome Transporter of Saccharomyces cerevisiae Mol. Biol. Cell, May 1, 2007; 18(5): 1790 - 1802. [Abstract] [Full Text] [PDF]

				J. Kota, M. Melin-Larsson, P. O. Ljungdahl, and H. Forsberg Ssh4, Rcr2 and Rcr1 Affect Plasma Membrane Transporter Activity in Saccharomyces cerevisiae Genetics, April 1, 2007; 175(4): 1681 - 1694. [Abstract] [Full Text] [PDF]

				M. Hayashi, T. Fukuzawa, H. Sorimachi, and T. Maeda Constitutive Activation of the pH-Responsive Rim101 Pathway in Yeast Mutants Defective in Late Steps of the MVB/ESCRT Pathway Mol. Cell. Biol., November 1, 2005; 25(21): 9478 - 9490. [Abstract] [Full Text] [PDF]

				K. Rothfels, J. C. Tanny, E. Molnar, H. Friesen, C. Commisso, and J. Segall Components of the ESCRT Pathway, DFG16, and YGR122w Are Required for Rim101 To Act as a Corepressor with Nrg1 at the Negative Regulatory Element of the DIT1 Gene of Saccharomyces cerevisiae Mol. Cell. Biol., August 1, 2005; 25(15): 6772 - 6788. [Abstract] [Full Text] [PDF]

				V. C. Culotta, M. Yang, and M. D. Hall Manganese Transport and Trafficking: Lessons Learned from Saccharomyces cerevisiae Eukaryot. Cell, July 1, 2005; 4(7): 1159 - 1165. [Full Text] [PDF]

				C. A. Reinke, P. Kozik, and B. S. Glick Golgi inheritance in small buds of Saccharomyces cerevisiae is linked to endoplasmic reticulum inheritance PNAS, December 28, 2004; 101(52): 18018 - 18023. [Abstract] [Full Text] [PDF]