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Hof1 and Rvs167 have redundant roles in actomyosin ring function during cytokinesis in budding yeast.

Nkosi PJ, Targosz BS, Labib K, Sanchez-Diaz A - PLoS ONE (2013)

Bottom Line: This new function of Rvs167 appears to be independent of its known role as a regulator of the Arp2/3 actin nucleator, as actin ring assembly is not abolished by the simultaneous inactivation of Hof1 and Arp2/3.Instead we find that recruitment to the bud-neck of the Iqg1 actin regulator is defective in cells lacking Hof1 and Rvs167, though future studies will be needed to determine if this reflects a direct interaction between these factors.The redundant role of Hof1 in actin ring assembly suggests that the mechanism of actin ring assembly has been conserved to a greater extent across evolution than anticipated previously.

View Article: PubMed Central - PubMed

Affiliation: Paterson Institute for Cancer Research, University of Manchester, Manchester, United Kingdom.

ABSTRACT
The Hof1 protein (Homologue of Fifteen) regulates formation of the primary septum during cytokinesis in the budding yeast Saccharomyces cerevisiae, whereas the orthologous Cdc15 protein in fission yeast regulates the actomyosin ring by using its F-BAR domain to recruit actin nucleators to the cleavage site. Here we show that budding yeast Hof1 also contributes to actin ring assembly in parallel with the Rvs167 protein. Simultaneous deletion of the HOF1 and RVS167 genes is lethal, and cells fail to assemble the actomyosin ring as they progress through mitosis. Although Hof1 and Rvs167 are not orthologues, they both share an analogous structure, with an F-BAR or BAR domain at the amino terminus, capable of inducing membrane curvature, and SH3 domains at the carboxyl terminus that bind to specific proline-rich targets. The SH3 domain of Rvs167 becomes essential for assembly of the actomyosin ring in cells lacking Hof1, suggesting that it helps to recruit a regulator of the actin cytoskeleton. This new function of Rvs167 appears to be independent of its known role as a regulator of the Arp2/3 actin nucleator, as actin ring assembly is not abolished by the simultaneous inactivation of Hof1 and Arp2/3. Instead we find that recruitment to the bud-neck of the Iqg1 actin regulator is defective in cells lacking Hof1 and Rvs167, though future studies will be needed to determine if this reflects a direct interaction between these factors. The redundant role of Hof1 in actin ring assembly suggests that the mechanism of actin ring assembly has been conserved to a greater extent across evolution than anticipated previously.

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The SH3 domain of Rvs167 becomes essential for cell proliferation in the absence of Hof1.(A) Tetrad analysis of diploid yeast cells lacking one copy of HOF1 and one copy of either RVS167 or CYK3. (B) Spores of the indicated genotypes were grown for 24 hours on YPD plates at 24°C. The scale bars indicate 20 µm. (C-D) Similar experiments illustrating that the SH3 domain of Rvs167 is essential in cells lacking Hof1. (E) The SH3 domain of Hof1 is essential in the absence of Cyk3 but dispensable in the absence of Rvs167. (F) The same is true for the F-BAR domain of Hof1. (G) Rvs167 does not become essential in the absence of Cyk3.
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pone-0057846-g001: The SH3 domain of Rvs167 becomes essential for cell proliferation in the absence of Hof1.(A) Tetrad analysis of diploid yeast cells lacking one copy of HOF1 and one copy of either RVS167 or CYK3. (B) Spores of the indicated genotypes were grown for 24 hours on YPD plates at 24°C. The scale bars indicate 20 µm. (C-D) Similar experiments illustrating that the SH3 domain of Rvs167 is essential in cells lacking Hof1. (E) The SH3 domain of Hof1 is essential in the absence of Cyk3 but dispensable in the absence of Rvs167. (F) The same is true for the F-BAR domain of Hof1. (G) Rvs167 does not become essential in the absence of Cyk3.

Mentions: In addition to Hof1, two other non-essential budding yeast proteins combine carboxy terminal SH3 domains with an F-BAR (Bzz1) or BAR (Rvs167) domain at the amino terminus. The Bzz1 protein is a component of cortical actin patches and interacts via its SH3 domain with regulators of the Arp2/3 actin nucleator [28]. We generated budding yeast cells that lacked both Hof1 and Bzz1, but did not observe a synthetic growth defect (BT, ASD and KL, unpublished data). Like Bzz1, the Rvs167 protein is a component of actin patches that interacts with Arp2/3 [29], [30], [31], [32]. Very recent work has shown by bimolecular fluorescence that Rvs167 also co-localises at the bud-neck with other cytokinesis factors such as Inn1, Cyk3 and Iqg1 (Mike Cundell and Clive Price, personal communication). We sporulated diploid cells lacking one copy of HOF1 as well as one copy of RVS167, and found by tetrad analysis of the meiotic progeny that the combination of hof1Δ with rvs167Δ was lethal (Figure 1A). Moreover, hof1Δ rvs167Δ cells had a rather similar phenotype to hof1Δ cyk3Δ (Figure 1B), suggestive of a defect in some aspect of cell cycle progression. It thus seems that Rvs167 becomes essential for cell proliferation in the absence of Hof1. In contrast, Rvs167 is not essential in cells lacking Cyk3 (Figure 1G).


Hof1 and Rvs167 have redundant roles in actomyosin ring function during cytokinesis in budding yeast.

Nkosi PJ, Targosz BS, Labib K, Sanchez-Diaz A - PLoS ONE (2013)

The SH3 domain of Rvs167 becomes essential for cell proliferation in the absence of Hof1.(A) Tetrad analysis of diploid yeast cells lacking one copy of HOF1 and one copy of either RVS167 or CYK3. (B) Spores of the indicated genotypes were grown for 24 hours on YPD plates at 24°C. The scale bars indicate 20 µm. (C-D) Similar experiments illustrating that the SH3 domain of Rvs167 is essential in cells lacking Hof1. (E) The SH3 domain of Hof1 is essential in the absence of Cyk3 but dispensable in the absence of Rvs167. (F) The same is true for the F-BAR domain of Hof1. (G) Rvs167 does not become essential in the absence of Cyk3.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3585203&req=5

pone-0057846-g001: The SH3 domain of Rvs167 becomes essential for cell proliferation in the absence of Hof1.(A) Tetrad analysis of diploid yeast cells lacking one copy of HOF1 and one copy of either RVS167 or CYK3. (B) Spores of the indicated genotypes were grown for 24 hours on YPD plates at 24°C. The scale bars indicate 20 µm. (C-D) Similar experiments illustrating that the SH3 domain of Rvs167 is essential in cells lacking Hof1. (E) The SH3 domain of Hof1 is essential in the absence of Cyk3 but dispensable in the absence of Rvs167. (F) The same is true for the F-BAR domain of Hof1. (G) Rvs167 does not become essential in the absence of Cyk3.
Mentions: In addition to Hof1, two other non-essential budding yeast proteins combine carboxy terminal SH3 domains with an F-BAR (Bzz1) or BAR (Rvs167) domain at the amino terminus. The Bzz1 protein is a component of cortical actin patches and interacts via its SH3 domain with regulators of the Arp2/3 actin nucleator [28]. We generated budding yeast cells that lacked both Hof1 and Bzz1, but did not observe a synthetic growth defect (BT, ASD and KL, unpublished data). Like Bzz1, the Rvs167 protein is a component of actin patches that interacts with Arp2/3 [29], [30], [31], [32]. Very recent work has shown by bimolecular fluorescence that Rvs167 also co-localises at the bud-neck with other cytokinesis factors such as Inn1, Cyk3 and Iqg1 (Mike Cundell and Clive Price, personal communication). We sporulated diploid cells lacking one copy of HOF1 as well as one copy of RVS167, and found by tetrad analysis of the meiotic progeny that the combination of hof1Δ with rvs167Δ was lethal (Figure 1A). Moreover, hof1Δ rvs167Δ cells had a rather similar phenotype to hof1Δ cyk3Δ (Figure 1B), suggestive of a defect in some aspect of cell cycle progression. It thus seems that Rvs167 becomes essential for cell proliferation in the absence of Hof1. In contrast, Rvs167 is not essential in cells lacking Cyk3 (Figure 1G).

Bottom Line: This new function of Rvs167 appears to be independent of its known role as a regulator of the Arp2/3 actin nucleator, as actin ring assembly is not abolished by the simultaneous inactivation of Hof1 and Arp2/3.Instead we find that recruitment to the bud-neck of the Iqg1 actin regulator is defective in cells lacking Hof1 and Rvs167, though future studies will be needed to determine if this reflects a direct interaction between these factors.The redundant role of Hof1 in actin ring assembly suggests that the mechanism of actin ring assembly has been conserved to a greater extent across evolution than anticipated previously.

View Article: PubMed Central - PubMed

Affiliation: Paterson Institute for Cancer Research, University of Manchester, Manchester, United Kingdom.

ABSTRACT
The Hof1 protein (Homologue of Fifteen) regulates formation of the primary septum during cytokinesis in the budding yeast Saccharomyces cerevisiae, whereas the orthologous Cdc15 protein in fission yeast regulates the actomyosin ring by using its F-BAR domain to recruit actin nucleators to the cleavage site. Here we show that budding yeast Hof1 also contributes to actin ring assembly in parallel with the Rvs167 protein. Simultaneous deletion of the HOF1 and RVS167 genes is lethal, and cells fail to assemble the actomyosin ring as they progress through mitosis. Although Hof1 and Rvs167 are not orthologues, they both share an analogous structure, with an F-BAR or BAR domain at the amino terminus, capable of inducing membrane curvature, and SH3 domains at the carboxyl terminus that bind to specific proline-rich targets. The SH3 domain of Rvs167 becomes essential for assembly of the actomyosin ring in cells lacking Hof1, suggesting that it helps to recruit a regulator of the actin cytoskeleton. This new function of Rvs167 appears to be independent of its known role as a regulator of the Arp2/3 actin nucleator, as actin ring assembly is not abolished by the simultaneous inactivation of Hof1 and Arp2/3. Instead we find that recruitment to the bud-neck of the Iqg1 actin regulator is defective in cells lacking Hof1 and Rvs167, though future studies will be needed to determine if this reflects a direct interaction between these factors. The redundant role of Hof1 in actin ring assembly suggests that the mechanism of actin ring assembly has been conserved to a greater extent across evolution than anticipated previously.

Show MeSH
Related in: MedlinePlus