Localization of the Tomato Bushy Stunt Virus Replication Protein p33 Reveals a Peroxisome-to-Endoplasmic Reticulum Sorting Pathway[W]

Abstract

Tomato bushy stunt virus (TBSV), a positive-strand RNA virus, causes extensive inward vesiculations of the peroxisomal boundary membrane and formation of peroxisomal multivesicular bodies (pMVBs). Although pMVBs are known to contain protein components of the viral membrane-bound RNA replication complex, the mechanisms of protein targeting to peroxisomal membranes and participation in pMVB biogenesis are not well understood. We show that the TBSV 33-kD replication protein (p33), expressed on its own, targets initially from the cytosol to peroxisomes, causing their progressive aggregation and eventually the formation of peroxisomal ghosts. These altered peroxisomes are distinct from pMVBs; they lack internal vesicles and are surrounded by novel cytosolic vesicles that contain p33 and appear to be derived from evaginations of the peroxisomal boundary membrane. Concomitant with these changes in peroxisomes, p33 and resident peroxisomal membrane proteins are relocalized to the peroxisomal endoplasmic reticulum (pER) subdomain. This sorting of p33 is disrupted by the coexpression of a dominant-negative mutant of ADP-ribosylation factor1, implicating coatomer in vesicle formation at peroxisomes. Mutational analysis of p33 revealed that its intracellular sorting is also mediated by several targeting signals, including three peroxisomal targeting elements that function cooperatively, plus a pER targeting signal resembling an Arg-based motif responsible for vesicle-mediated retrieval of escaped ER membrane proteins from the Golgi. These results provide insight into virus-induced intracellular rearrangements and reveal a peroxisome-to-pER sorting pathway, raising new mechanistic questions regarding the biogenesis of peroxisomes in plants.

The participation of plant cell organelles in compatible and incompatible potato virus Y-tobacco and -potato plant interaction

“…The process of RNA replication could be confined to a specific ''safeguarded'' cytoplasm compartment, preventing the activation of certain host defence mechanisms, as was first proposed on the example of TMV (Riedel et al 1998). If cellular organelles such as lysosomes, chloroplast, peroxisomes, endosomes are suggested to be the replication site for the tymovirus and tombusvirus, it is possible that potyviruses do not only exploit the endoplasmatic reticulum (McCartney et al 2005;Prod'homme et al 2001). Most of the data used to understand host responses to potyviruses have been obtained from biochemical and physiological aspects of investigations, rather than from single cells and organelles.…”

Light Induces Peroxisome Proliferation in Arabidopsis Seedlings through the Photoreceptor Phytochrome A, the Transcription Factor HY5 HOMOLOG, and the Peroxisomal Protein PEROXIN11b

“…Plant peroxisomes can be categorized into several variants that are structurally similar but metabolically distinct, such as glyoxysomes in seeds and germinating seedlings, leaf peroxisomes, glyoxysome-related gerontosomes in senescent tissue, nodule-specific peroxisomes, and unspecialized peroxisomes. Functions attributed to plant peroxisomes include metabolism of lipids, reactive oxygen species, and nitrogen, photorespiration, plant hormone biosynthesis and metabolism, and plant pathogen interaction (Beevers, 1979;Olsen and Harada, 1995;Zolman et al, 2000;Hayashi and Nishimura, 2003;Lipka et al, 2005;McCartney et al, 2005;Nyathi and Baker, 2006;Reumann and Weber, 2006).…”

The life of the peroxisome: from birth to death

“…Relocation of peroxisome membrane proteins to the ER was observed in response to TBSV infection in tobacco cells, and was inhibited by co-expression of a dominant negative ADP-ribosylation factor 1 (ARF1) mutant [15]. In Chlamydomonas reinhardtii, treatment with Brefeldin A (BFA), an inhibitor of the GTP exchange factor for ARF1, also inhibits fatty acid breakdown, a process which relies on peroxisomal -oxidation [19].…”

“…Viruses are extremely powerful tools to study cell biology and are providing insight into possible de novo routes of peroxisome formation in plants. Tombus viruses such as Cucmber Necrosis Virus (CNV) and Tomato Bushy Stunt Virus (TBSV) are known to highjack peroxisomes for replication through the action of replication protein p33 [15]. Recently, the ER-localised vesicle transport protein Sec39p in S. cerevisiae and Sec39-like protein in tobacco were shown to be required for TBSV replication [16].…”