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A tether for Woronin body inheritance is associated with evolutionary variation in organelle positioning.

Ng SK, Liu F, Lai J, Low W, Jedd G - PLoS Genet. (2009)

Bottom Line: In most species, WBs are tethered directly to the pore rim, however, Neurospora and relatives have evolved a delocalized pattern of cortex association.Using a new method for the construction of chromosomally encoded fusion proteins, marker fusion tagging (MFT), we show that a LAH-1/LAH-2 fusion can reproduce the ancestral pattern in Neurospora.Our results identify the link between the WB and cell cortex and suggest that splitting of leashin played a key role in the adaptive evolution of organelle localization.

View Article: PubMed Central - PubMed

Affiliation: Temasek Life Sciences Laboratory and Department of Biological Sciences, National University of Singapore, Singapore.

ABSTRACT
Eukaryotic organelles evolve to support the lifestyle of evolutionarily related organisms. In the fungi, filamentous Ascomycetes possess dense-core organelles called Woronin bodies (WBs). These organelles originate from peroxisomes and perform an adaptive function to seal septal pores in response to cellular wounding. Here, we identify Leashin, an organellar tether required for WB inheritance, and associate it with evolutionary variation in the subcellular pattern of WB distribution. In Neurospora, the leashin (lah) locus encodes two related adjacent genes. N-terminal sequences of LAH-1 bind WBs via the WB-specific membrane protein WSC, and C-terminal sequences are required for WB inheritance by cell cortex association. LAH-2 is localized to the hyphal apex and septal pore rim and plays a role in colonial growth. In most species, WBs are tethered directly to the pore rim, however, Neurospora and relatives have evolved a delocalized pattern of cortex association. Using a new method for the construction of chromosomally encoded fusion proteins, marker fusion tagging (MFT), we show that a LAH-1/LAH-2 fusion can reproduce the ancestral pattern in Neurospora. Our results identify the link between the WB and cell cortex and suggest that splitting of leashin played a key role in the adaptive evolution of organelle localization.

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The leashin mutant is defective in Woronin body inheritance.(A) The lah mutant accumulates HEX assemblies in the apical compartment. The distribution of HEX assemblies was quantified in apical (a) and sub-apical (sa) hyphal compartments in the indicated strains. (B) HEX assemblies are enveloped by WSC in the lah mutant background. RFP-PTS1 reveals the peroxisome matrix and WSC-GFP reveals assembly of the sorting complex. HEX assemblies can be seen in the DIC channel. Arrowhead points to a pair of aberrantly associated nascent WBs. Bar = 2 µm. (C) Dot plots reveal repetitive sequences R1, R2 and R3 in the predicted LAH polypeptide. The schematic indicates conserved regions (black bars) and repeat regions (light gray bars). Red bars indicate two predicted coiled-coil domains. (D) Alignment of repetitive sequences using Clustal W [44]. R1 contains 18 repeats centered on a core consensus sequence, LPVDEDLDLLPALPES, and R2 and R3 contain 33 repeats of the consensus sequence, PEEVELPASP. Acidic residues are colored blue, basic residues are red, hydrophobic sequences are green and Proline is indicated in yellow.
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pgen-1000521-g001: The leashin mutant is defective in Woronin body inheritance.(A) The lah mutant accumulates HEX assemblies in the apical compartment. The distribution of HEX assemblies was quantified in apical (a) and sub-apical (sa) hyphal compartments in the indicated strains. (B) HEX assemblies are enveloped by WSC in the lah mutant background. RFP-PTS1 reveals the peroxisome matrix and WSC-GFP reveals assembly of the sorting complex. HEX assemblies can be seen in the DIC channel. Arrowhead points to a pair of aberrantly associated nascent WBs. Bar = 2 µm. (C) Dot plots reveal repetitive sequences R1, R2 and R3 in the predicted LAH polypeptide. The schematic indicates conserved regions (black bars) and repeat regions (light gray bars). Red bars indicate two predicted coiled-coil domains. (D) Alignment of repetitive sequences using Clustal W [44]. R1 contains 18 repeats centered on a core consensus sequence, LPVDEDLDLLPALPES, and R2 and R3 contain 33 repeats of the consensus sequence, PEEVELPASP. Acidic residues are colored blue, basic residues are red, hydrophobic sequences are green and Proline is indicated in yellow.

Mentions: In a screen for genes involved in WB segregation, we identified a spontaneous mutation that behaves as a single recessive locus and accumulates HEX assemblies in the apical compartment (Figure 1A) and based on our functional analysis, we named this locus leashin (lah). To assess the effect of the lah mutation on the function of WSC, the lah mutant was transformed to express WSC-GFP and RFP-PTS1 (A marker of the peroxisome matrix). In the lah background, WSC envelops HEX assemblies to produce budding intermediates similar to those observed in wild-type cells [14], however, these accumulate and aggregate aberrantly (Figure 1B) in the apical hyphal compartment, suggesting that LAH functions downstream of WSC and plays a role in WB inheritance.


A tether for Woronin body inheritance is associated with evolutionary variation in organelle positioning.

Ng SK, Liu F, Lai J, Low W, Jedd G - PLoS Genet. (2009)

The leashin mutant is defective in Woronin body inheritance.(A) The lah mutant accumulates HEX assemblies in the apical compartment. The distribution of HEX assemblies was quantified in apical (a) and sub-apical (sa) hyphal compartments in the indicated strains. (B) HEX assemblies are enveloped by WSC in the lah mutant background. RFP-PTS1 reveals the peroxisome matrix and WSC-GFP reveals assembly of the sorting complex. HEX assemblies can be seen in the DIC channel. Arrowhead points to a pair of aberrantly associated nascent WBs. Bar = 2 µm. (C) Dot plots reveal repetitive sequences R1, R2 and R3 in the predicted LAH polypeptide. The schematic indicates conserved regions (black bars) and repeat regions (light gray bars). Red bars indicate two predicted coiled-coil domains. (D) Alignment of repetitive sequences using Clustal W [44]. R1 contains 18 repeats centered on a core consensus sequence, LPVDEDLDLLPALPES, and R2 and R3 contain 33 repeats of the consensus sequence, PEEVELPASP. Acidic residues are colored blue, basic residues are red, hydrophobic sequences are green and Proline is indicated in yellow.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2690989&req=5

pgen-1000521-g001: The leashin mutant is defective in Woronin body inheritance.(A) The lah mutant accumulates HEX assemblies in the apical compartment. The distribution of HEX assemblies was quantified in apical (a) and sub-apical (sa) hyphal compartments in the indicated strains. (B) HEX assemblies are enveloped by WSC in the lah mutant background. RFP-PTS1 reveals the peroxisome matrix and WSC-GFP reveals assembly of the sorting complex. HEX assemblies can be seen in the DIC channel. Arrowhead points to a pair of aberrantly associated nascent WBs. Bar = 2 µm. (C) Dot plots reveal repetitive sequences R1, R2 and R3 in the predicted LAH polypeptide. The schematic indicates conserved regions (black bars) and repeat regions (light gray bars). Red bars indicate two predicted coiled-coil domains. (D) Alignment of repetitive sequences using Clustal W [44]. R1 contains 18 repeats centered on a core consensus sequence, LPVDEDLDLLPALPES, and R2 and R3 contain 33 repeats of the consensus sequence, PEEVELPASP. Acidic residues are colored blue, basic residues are red, hydrophobic sequences are green and Proline is indicated in yellow.
Mentions: In a screen for genes involved in WB segregation, we identified a spontaneous mutation that behaves as a single recessive locus and accumulates HEX assemblies in the apical compartment (Figure 1A) and based on our functional analysis, we named this locus leashin (lah). To assess the effect of the lah mutation on the function of WSC, the lah mutant was transformed to express WSC-GFP and RFP-PTS1 (A marker of the peroxisome matrix). In the lah background, WSC envelops HEX assemblies to produce budding intermediates similar to those observed in wild-type cells [14], however, these accumulate and aggregate aberrantly (Figure 1B) in the apical hyphal compartment, suggesting that LAH functions downstream of WSC and plays a role in WB inheritance.

Bottom Line: In most species, WBs are tethered directly to the pore rim, however, Neurospora and relatives have evolved a delocalized pattern of cortex association.Using a new method for the construction of chromosomally encoded fusion proteins, marker fusion tagging (MFT), we show that a LAH-1/LAH-2 fusion can reproduce the ancestral pattern in Neurospora.Our results identify the link between the WB and cell cortex and suggest that splitting of leashin played a key role in the adaptive evolution of organelle localization.

View Article: PubMed Central - PubMed

Affiliation: Temasek Life Sciences Laboratory and Department of Biological Sciences, National University of Singapore, Singapore.

ABSTRACT
Eukaryotic organelles evolve to support the lifestyle of evolutionarily related organisms. In the fungi, filamentous Ascomycetes possess dense-core organelles called Woronin bodies (WBs). These organelles originate from peroxisomes and perform an adaptive function to seal septal pores in response to cellular wounding. Here, we identify Leashin, an organellar tether required for WB inheritance, and associate it with evolutionary variation in the subcellular pattern of WB distribution. In Neurospora, the leashin (lah) locus encodes two related adjacent genes. N-terminal sequences of LAH-1 bind WBs via the WB-specific membrane protein WSC, and C-terminal sequences are required for WB inheritance by cell cortex association. LAH-2 is localized to the hyphal apex and septal pore rim and plays a role in colonial growth. In most species, WBs are tethered directly to the pore rim, however, Neurospora and relatives have evolved a delocalized pattern of cortex association. Using a new method for the construction of chromosomally encoded fusion proteins, marker fusion tagging (MFT), we show that a LAH-1/LAH-2 fusion can reproduce the ancestral pattern in Neurospora. Our results identify the link between the WB and cell cortex and suggest that splitting of leashin played a key role in the adaptive evolution of organelle localization.

Show MeSH