Pex11-related Proteins in Peroxisome Dynamics: A Role for the Novel Peroxin Pex27p in Controlling Peroxisome Size and Number inSaccharomyces cerevisiae

Abstract

Transcriptome profiling identified the gene PEX25 encoding Pex25p, a peroxisomal membrane peroxin required for the regulation of peroxisome size and maintenance in Saccharomyces cerevisiae. Pex25p is related to a protein of unknown function encoded by the open reading frame, YOR193w, of the S. cerevisiae genome. Yor193p is a peripheral peroxisomal membrane protein that exhibits high sequence similarity not only to Pex25p but also to the peroxisomal membrane peroxin Pex11p. Unlike Pex25p and Pex11p, Yor193p is constitutively expressed in wild-type cells grown in oleic acid-containing medium, the metabolism of which requires intact peroxisomes. Cells deleted for the YOR193w gene show a few enlarged peroxisomes. Peroxisomes are greatly enlarged in cells harboring double deletions of the YOR193w and PEX25 genes, the YOR193w and PEX11 genes, and the PEX25 and PEX11 genes. Yeast two-hybrid analyses showed that Yor193p interacts with Pex25p and itself, Pex25p interacts with Yor193p and itself, and Pex11p interacts only with itself. Overexpression of YOR193w, PEX25, or PEX11 led to peroxisome proliferation and the formation of small peroxisomes. Our data suggest a role for Yor193p, renamed Pex27p, in controlling peroxisome size and number in S. cerevisiae.

An ancestral role in peroxisome assembly is retained by the divisional peroxin Pex11 in the yeast Yarrowia lipolytica

“…PEX27 remain constant, in S. cerevisiae during incubation in oleic acid medium (Erdmann and Blobel, 1995;Smith et al, 2002;Tam et al, 2003). Semi-quantitative RT-PCR was performed to determine transcript levels of the PEX11, PEX11C and PEX11/25 genes in Y. lipolytica during a switch from glucose medium to oleic acid medium (Fig.…”

“…Confocal fluorescence microscopy (Tower et al, 2011), electron microscopy and morphometric analysis (Eitzen et al, 1997;Tam et al, 2003), and immunofluorescence microscopy (Tam and Rachubinski, 2002) were performed as described previously.…”

“…Likewise, all three proteins share partially redundant function in peroxisome division; overexpression of PEX11, PEX25 or PEX27 leads to cells with increased numbers of small peroxisomes, whereas deletion of any of these genes leads to cells with decreased numbers of enlarged peroxisomes (Smith et al, 2002;Rottensteiner et al, 2003;Tam et al, 2003). Bioinformatic analysis identified Pex11Bp, Pex11Cp and Pex11/ 25p as putative homologs of Pex11p in fungi (Kiel et al, 2006).…”

Binding and Functions of ADP-ribosylation Factor on Mammalian and Yeast Peroxisomes

“…Since only Pex11␣p is stimulated by hypolipidemic drugs, this isoform was supposed to be involved in the induced proliferation, whereas Pex11␤p might regulate the constitutive process (66). Similarly, in S. cerevisiae, a family of Pex11p proteins comprising Pex11p, Pex25p, and Pex27p was identified that is required for peroxisome biogenesis regulating peroxisome abundance (67,68). Recently, an interaction between Pex25p and the small GTPase Rho1p was suggested to play a role in controlling yeast peroxisome membrane dynamics (69).…”

Protein Translocation Across the Peroxisomal Membrane

“…Using many different organisms as experimental models (from Saccharomyces cerevisiae to mammalian cells), several laboratories have been quite successful in the task of identifying the genes involved in peroxisomal biogenesis. Almost 30 different genes involved in this process are known (3,5,9,16,17). The proteins they encode are designated by the word peroxin (Pex) followed by a number reflecting the order of their discovery (18).…”