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YHR150w and YDR479c encode peroxisomal integral membrane proteins involved in the regulation of peroxisome number, size, and distribution in Saccharomyces cerevisiae.

Vizeacoumar FJ, Torres-Guzman JC, Tam YY, Aitchison JD, Rachubinski RA - J. Cell Biol. (2003)

Bottom Line: Peroxisomes isolated from cells deleted for both genes have a decreased buoyant density compared with peroxisomes isolated from wild-type cells and still exhibit clustering and peroxisomal membrane thickening.Together, our data suggest a role for Yhr150p and Ydr479p, together with Pex25p and Vps1p, in regulating peroxisome number, size, and distribution in S. cerevisiae.Because of their role in peroxisome dynamics, YHR150w and YDR479c have been designated as PEX28 and PEX29, respectively, and their encoded peroxins as Pex28p and Pex29p.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell Biology, University of Alberta, Medical Sciences Building 5-14, Edmonton, Alberta T6G 2H7, Canada.

ABSTRACT
The peroxin Pex24p of the yeast Yarrowia lipolytica exhibits high sequence similarity to two hypothetical proteins, Yhr150p and Ydr479p, encoded by the Saccharomyces cerevisiae genome. Like YlPex24p, both Yhr150p and Ydr479p have been shown to be integral to the peroxisomal membrane, but unlike YlPex24p, their levels of synthesis are not increased upon a shift of cells from glucose- to oleic acid-containing medium. Peroxisomes of cells deleted for either or both of the YHR150w and YDR479c genes are increased in number, exhibit extensive clustering, are smaller in area than peroxisomes of wild-type cells, and often exhibit membrane thickening between adjacent peroxisomes in a cluster. Peroxisomes isolated from cells deleted for both genes have a decreased buoyant density compared with peroxisomes isolated from wild-type cells and still exhibit clustering and peroxisomal membrane thickening. Overexpression of the genes PEX25 or VPS1, but not the gene PEX11, restored the wild-type phenotype to cells deleted for one or both of the YHR150w and YDR479c genes. Together, our data suggest a role for Yhr150p and Ydr479p, together with Pex25p and Vps1p, in regulating peroxisome number, size, and distribution in S. cerevisiae. Because of their role in peroxisome dynamics, YHR150w and YDR479c have been designated as PEX28 and PEX29, respectively, and their encoded peroxins as Pex28p and Pex29p.

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Ultrastructure of yhr150Δ/ydr479Δ cells overexpressing YHR150w, YDR479c, PEX11, PEX25, or VPS1. Cells of the yhr150Δ/ydr479Δ strain overexpressing YHR150w (A), YDR479c (B), PEX11 (C), PEX25 (D), or VPS1 (E) were grown in SM medium overnight, transferred to YPBO medium, and incubated in YPBO medium for 8 h. P, peroxisome; P*, peroxisome cluster. Bar, 0.5 μm.
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fig8: Ultrastructure of yhr150Δ/ydr479Δ cells overexpressing YHR150w, YDR479c, PEX11, PEX25, or VPS1. Cells of the yhr150Δ/ydr479Δ strain overexpressing YHR150w (A), YDR479c (B), PEX11 (C), PEX25 (D), or VPS1 (E) were grown in SM medium overnight, transferred to YPBO medium, and incubated in YPBO medium for 8 h. P, peroxisome; P*, peroxisome cluster. Bar, 0.5 μm.

Mentions: Because cells deleted for one or both of the YHR150w and YDR479c genes are compromised in their regulation of peroxisome number, size, and distribution, we investigated the effects of overexpression of three genes previously shown to be involved in these processes in S. cerevisiae. Cells of strains mutant for the genes encoding the peroxisomal peroxins Pex11p (Erdmann and Blobel, 1995; Marshall et al., 1995, 1996), Pex25p (Smith et al., 2002), and the dynamin-like protein Vps1p (Hoepfner et al., 2001) have reduced numbers of enlarged peroxisomes compared with wild-type cells (see Fig. S1, available at http://www.jcb.org/cgi/content/full/jcb.200210130/DC1). Overexpression of PEX25 (Fig. 7 ; Fig. 8 D) or VPS1 (Fig. 7; Fig. 8 E) in cells deleted for one or both of the YHR150w and YDR479c genes led to a partial restoration of the wild-type peroxisomal phenotype, with overexpressing cells containing increased numbers of separate, individual peroxisomes and reduced numbers of peroxisomal clusters (see Figs. S5 and S6, available at http://www.jcb.org/cgi/content/full/jcb.200210130/DC1). In contrast, overexpression of PEX11 did not appear to have any effect on the abnormal peroxisome morphology observed in cells mutant for the YHR150w and YDR479c genes (Fig. 7; Fig. 8 C; Fig. S4, available at http://www.jcb.org/cgi/content/full/jcb.200210130/DC1). It should be noted that overexpression of the YHR150w gene led to restoration of wild-type peroxisome morphology in yhr150Δ cells but not in ydr479Δ cells or in cells deleted for both the YHR150w and YDR479c genes (Fig. 7, Fig. 8 A; Fig. S2, available at http://www.jcb.org/cgi/content/full/jcb.200210130/DC1). In contrast, overexpression of YDR479c led to restoration of wild-type peroxisome morphology not only in ydr479Δ cells, but also in yhr150Δ cells and cells deleted for both genes (Fig. 7; Fig. 8 B; Fig. S3, available at http://www.jcb.org/cgi/content/full/jcb.200210130/DC1). Therefore, it appears that Yhr150p may be, for the most part, redundant in its functions in regulating peroxisome dynamics with respect to Ydr479p. Attempts at demonstrating physical interactions, either direct or indirect, between Yhr150p and Ydr479p or between these two proteins and Pex11p, Pex25p, or Vps1p were unsuccessful (unpublished data).


YHR150w and YDR479c encode peroxisomal integral membrane proteins involved in the regulation of peroxisome number, size, and distribution in Saccharomyces cerevisiae.

Vizeacoumar FJ, Torres-Guzman JC, Tam YY, Aitchison JD, Rachubinski RA - J. Cell Biol. (2003)

Ultrastructure of yhr150Δ/ydr479Δ cells overexpressing YHR150w, YDR479c, PEX11, PEX25, or VPS1. Cells of the yhr150Δ/ydr479Δ strain overexpressing YHR150w (A), YDR479c (B), PEX11 (C), PEX25 (D), or VPS1 (E) were grown in SM medium overnight, transferred to YPBO medium, and incubated in YPBO medium for 8 h. P, peroxisome; P*, peroxisome cluster. Bar, 0.5 μm.
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fig8: Ultrastructure of yhr150Δ/ydr479Δ cells overexpressing YHR150w, YDR479c, PEX11, PEX25, or VPS1. Cells of the yhr150Δ/ydr479Δ strain overexpressing YHR150w (A), YDR479c (B), PEX11 (C), PEX25 (D), or VPS1 (E) were grown in SM medium overnight, transferred to YPBO medium, and incubated in YPBO medium for 8 h. P, peroxisome; P*, peroxisome cluster. Bar, 0.5 μm.
Mentions: Because cells deleted for one or both of the YHR150w and YDR479c genes are compromised in their regulation of peroxisome number, size, and distribution, we investigated the effects of overexpression of three genes previously shown to be involved in these processes in S. cerevisiae. Cells of strains mutant for the genes encoding the peroxisomal peroxins Pex11p (Erdmann and Blobel, 1995; Marshall et al., 1995, 1996), Pex25p (Smith et al., 2002), and the dynamin-like protein Vps1p (Hoepfner et al., 2001) have reduced numbers of enlarged peroxisomes compared with wild-type cells (see Fig. S1, available at http://www.jcb.org/cgi/content/full/jcb.200210130/DC1). Overexpression of PEX25 (Fig. 7 ; Fig. 8 D) or VPS1 (Fig. 7; Fig. 8 E) in cells deleted for one or both of the YHR150w and YDR479c genes led to a partial restoration of the wild-type peroxisomal phenotype, with overexpressing cells containing increased numbers of separate, individual peroxisomes and reduced numbers of peroxisomal clusters (see Figs. S5 and S6, available at http://www.jcb.org/cgi/content/full/jcb.200210130/DC1). In contrast, overexpression of PEX11 did not appear to have any effect on the abnormal peroxisome morphology observed in cells mutant for the YHR150w and YDR479c genes (Fig. 7; Fig. 8 C; Fig. S4, available at http://www.jcb.org/cgi/content/full/jcb.200210130/DC1). It should be noted that overexpression of the YHR150w gene led to restoration of wild-type peroxisome morphology in yhr150Δ cells but not in ydr479Δ cells or in cells deleted for both the YHR150w and YDR479c genes (Fig. 7, Fig. 8 A; Fig. S2, available at http://www.jcb.org/cgi/content/full/jcb.200210130/DC1). In contrast, overexpression of YDR479c led to restoration of wild-type peroxisome morphology not only in ydr479Δ cells, but also in yhr150Δ cells and cells deleted for both genes (Fig. 7; Fig. 8 B; Fig. S3, available at http://www.jcb.org/cgi/content/full/jcb.200210130/DC1). Therefore, it appears that Yhr150p may be, for the most part, redundant in its functions in regulating peroxisome dynamics with respect to Ydr479p. Attempts at demonstrating physical interactions, either direct or indirect, between Yhr150p and Ydr479p or between these two proteins and Pex11p, Pex25p, or Vps1p were unsuccessful (unpublished data).

Bottom Line: Peroxisomes isolated from cells deleted for both genes have a decreased buoyant density compared with peroxisomes isolated from wild-type cells and still exhibit clustering and peroxisomal membrane thickening.Together, our data suggest a role for Yhr150p and Ydr479p, together with Pex25p and Vps1p, in regulating peroxisome number, size, and distribution in S. cerevisiae.Because of their role in peroxisome dynamics, YHR150w and YDR479c have been designated as PEX28 and PEX29, respectively, and their encoded peroxins as Pex28p and Pex29p.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell Biology, University of Alberta, Medical Sciences Building 5-14, Edmonton, Alberta T6G 2H7, Canada.

ABSTRACT
The peroxin Pex24p of the yeast Yarrowia lipolytica exhibits high sequence similarity to two hypothetical proteins, Yhr150p and Ydr479p, encoded by the Saccharomyces cerevisiae genome. Like YlPex24p, both Yhr150p and Ydr479p have been shown to be integral to the peroxisomal membrane, but unlike YlPex24p, their levels of synthesis are not increased upon a shift of cells from glucose- to oleic acid-containing medium. Peroxisomes of cells deleted for either or both of the YHR150w and YDR479c genes are increased in number, exhibit extensive clustering, are smaller in area than peroxisomes of wild-type cells, and often exhibit membrane thickening between adjacent peroxisomes in a cluster. Peroxisomes isolated from cells deleted for both genes have a decreased buoyant density compared with peroxisomes isolated from wild-type cells and still exhibit clustering and peroxisomal membrane thickening. Overexpression of the genes PEX25 or VPS1, but not the gene PEX11, restored the wild-type phenotype to cells deleted for one or both of the YHR150w and YDR479c genes. Together, our data suggest a role for Yhr150p and Ydr479p, together with Pex25p and Vps1p, in regulating peroxisome number, size, and distribution in S. cerevisiae. Because of their role in peroxisome dynamics, YHR150w and YDR479c have been designated as PEX28 and PEX29, respectively, and their encoded peroxins as Pex28p and Pex29p.

Show MeSH
Related in: MedlinePlus