QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

Vol. 16, Issue 10, 4941-4953, October 2005

This Article Full Text Full Text (PDF) All Versions of this Article: E05-02-0143v1 16/10/4941    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Chang, T. Articles by Dunn, W. A. Search for Related Content PubMed PubMed Citation Articles by Chang, T. Articles by Dunn, W. A., Jr.

PpATG9 Encodes a Novel Membrane Protein That Traffics to Vacuolar Membranes, Which Sequester Peroxisomes during Pexophagy in Pichia pastoris

Tina Chang ^*, Laura A. Schroder ^*, J. Michael Thomson ^*, Amy S. Klocman ^*, Amber J. Tomasini ^*, Per E. Strømhaug , and William A. Dunn, Jr. ^*

^* Department of Anatomy and Cell Biology, University of Florida College of Medicine, Gainesville, FL 32610-0235; Division of Biological Sciences, University of Missouri, Columbia, MO 65201

Submitted February 22, 2005; Revised July 21, 2005; Accepted July 22, 2005
Monitoring Editor: Suresh Subramani

When Pichia pastoris adapts from methanol to glucose growth, peroxisomes are rapidly sequestered and degraded within the vacuole by micropexophagy. During micropexophagy, sequestering membranes arise from the vacuole to engulf the peroxisomes. Fusion of the sequestering membranes and incorporation of the peroxisomes into the vacuole is mediated by the micropexophagy-specific membrane apparatus (MIPA). In this study, we show the P. pastoris ortholog of Atg9, a novel membrane protein is essential for the formation of the sequestering membranes and assembly of MIPA. During methanol growth, GFP-PpAtg9 localizes to multiple structures situated near the plasma membrane referred as the peripheral compartment (Atg9-PC). On glucose-induced micropexophagy, PpAtg9 traffics from the Atg9-PC to unique perivacuolar structures (PVS) that contain PpAtg11, but lack PpAtg2 and PpAtg8. Afterward, PpAtg9 distributes to the vacuole surface and sequestering membranes. Movement of the PpAtg9 from the Atg9-PC to the PVS requires PpAtg11 and PpVps15. PpAtg2 and PpAtg7 are essential for PpAtg9 trafficking from the PVS to the vacuole and sequestering membranes, whereas trafficking of PpAtg9 proceeds independent of PpAtg1, PpAtg18, and PpVac8. In summary, our data suggest that PpAtg9 transits from the Atg9-PC to the PVS and then to the sequestering membranes that engulf the peroxisomes for degradation.

Abbreviations used: AOX, alcohol oxidase; FM 4-64, N-(triethylammoniumpropyl)-4-(p-diethylaminophenylhexatrienyl) pyridinium dibromide; TCA, trichloroacetic acid; GFP, green fluorescent protein; BFP, blue fluorescent protein; mRFP, monomeric red fluorescent protein; GSA, glucose-induced selective autophagy; REMI, restriction enzyme-mediated integration; CVT, cytoplasm-to-vacuole targeting; Atg9-PC, Atg9 peripheral compartment; PVS, perivacuolar structure; MIPA, micropexophagy-specific membrane apparatus; PAS, pre-autophagosome structure.

Address correspondence to: William A. Dunn Jr. (dunn{at}ufl.edu).

This article has been cited by other articles:

				L. A. Schroder, M. V. Ortiz, and W. A. Dunn Jr. The Membrane Dynamics of Pexophagy Are Influenced by Sar1p in Pichia pastoris Mol. Biol. Cell, November 1, 2008; 19(11): 4888 - 4899. [Abstract] [Full Text] [PDF]

				R. Krick, Y. Muehe, T. Prick, S. Bremer, P. Schlotterhose, E.-L. Eskelinen, J. Millen, D. S. Goldfarb, and M. Thumm Piecemeal Microautophagy of the Nucleus Requires the Core Macroautophagy Genes Mol. Biol. Cell, October 1, 2008; 19(10): 4492 - 4505. [Abstract] [Full Text] [PDF]

				T. Y. Nazarko, A. S. Polupanov, R. R. Manjithaya, S. Subramani, and A. A. Sibirny The Requirement of Sterol Glucoside for Pexophagy in Yeast Is Dependent on the Species and Nature of Peroxisome Inducers Mol. Biol. Cell, January 1, 2007; 18(1): 106 - 118. [Abstract] [Full Text] [PDF]

				A. R. J. Young, E. Y. W. Chan, X. W. Hu, R. Kochl, S. G. Crawshaw, S. High, D. W. Hailey, J. Lippincott-Schwartz, and S. A. Tooze Starvation and ULK1-dependent cycling of mammalian Atg9 between the TGN and endosomes J. Cell Sci., September 15, 2006; 119(18): 3888 - 3900. [Abstract] [Full Text] [PDF]

				F. Reggiori and D. J. Klionsky Atg9 sorting from mitochondria is impaired in early secretion and VFT-complex mutants in Saccharomyces cerevisiae J. Cell Sci., July 15, 2006; 119(14): 2903 - 2911. [Abstract] [Full Text] [PDF]