This Article Full Text Full Text (PDF) All Versions of this Article: 17/10/2723    most recent tpc.105.034975v1 Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science 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 CrossRef Citing Articles via ISI Web of Science (9) Citing Articles via Google Scholar Google Scholar Articles by Brukhin, V. Articles by Grossniklaus, U. Search for Related Content PubMed PubMed Citation Articles by Brukhin, V. Articles by Grossniklaus, U. Agricola Articles by Brukhin, V. Articles by Grossniklaus, U.

The RPN1 Subunit of the 26S Proteasome in Arabidopsis Is Essential for Embryogenesis

^a Institute of Plant Biology and Zürich-Basel Plant Science Center, University of Zürich, CH-8008 Zürich, Switzerland
^b Institut de Biologie Moléculaire des Plantes, Centre National de la Recherche Scientifique, F-67084 Strasbourg, France

¹ To whom correspondence should be addressed. E-mail grossnik{at}botinst.unizh.ch; fax 41-1-634-82-04.

The 26S proteasome plays a central role in the degradation of regulatory proteins involved in a variety of developmental processes. It consists of two multisubunit protein complexes: the proteolytic core protease and the regulatory particle (RP). The function of most RP subunits is poorly understood. Here, we describe mutants in the Arabidopsis thaliana RPN1 subunit, which is encoded by two paralogous genes, RPN1a and RPN1b. Disruption of RPN1a caused embryo lethality, while RPN1b mutants showed no obvious abnormal phenotype. Embryos homozygous for rpn1a arrested at the globular stage with defects in the formation of the embryonic root, the protoderm, and procambium. Cyclin B1 protein was not degraded in these embryos, consistent with cell division defects. Double mutant plants (rpn1a/RPN1a rpn1b/rpn1b) produced embryos with a phenotype indistinguishable from that of the rpn1a single mutant. Thus, despite their largely overlapping expression patterns in flowers and developing seeds, the two isoforms do not share redundant functions during gametogenesis and embryogenesis. However, complementation of the rpn1a mutation with the coding region of RPN1b expressed under the control of the RPN1a promoter indicates that the two RPN1 isoforms are functionally equivalent. Overall, our data indicate that RPN1 activity is essential during embryogenesis, where it might participate in the destruction of a specific set of protein substrates.

This article has been cited by other articles:

				J. Puyaubert, L. Denis, and C. Alban Dual Targeting of Arabidopsis HOLOCARBOXYLASE SYNTHETASE1: A Small Upstream Open Reading Frame Regulates Translation Initiation and Protein Targeting Plant Physiology, February 1, 2008; 146(2): 478 - 491. [Abstract] [Full Text] [PDF]

				M. E. Griffith, U. Mayer, A. Capron, Q. A. Ngo, A. Surendrarao, R. McClinton, G. Jurgens, and V. Sundaresan The TORMOZ Gene Encodes a Nucleolar Protein Required for Regulated Division Planes and Embryo Development in Arabidopsis PLANT CELL, July 1, 2007; 19(7): 2246 - 2263. [Abstract] [Full Text] [PDF]

				H. Jin, S. Li, and A. Villegas Jr. Down-Regulation of the 26S Proteasome Subunit RPN9 Inhibits Viral Systemic Transport and Alters Plant Vascular Development Plant Physiology, October 1, 2006; 142(2): 651 - 661. [Abstract] [Full Text] [PDF]

				Y.-H. Ding, N.-Y. Liu, Z.-S. Tang, J. Liu, and W.-C. Yang Arabidopsis GLUTAMINE-RICH PROTEIN23 Is Essential for Early Embryogenesis and Encodes a Novel Nuclear PPR Motif Protein That Interacts with RNA Polymerase II Subunit III PLANT CELL, April 1, 2006; 18(4): 815 - 830. [Abstract] [Full Text] [PDF]