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Protein cofactor competition regulates the action of a multifunctional RNA helicase in different pathways.

Heininger AU, Hackert P, Andreou AZ, Boon KL, Memet I, Prior M, Clancy A, Schmidt B, Urlaub H, Schleiff E, Sloan KE, Deckers M, Lührmann R, Enderlein J, Klostermeier D, Rehling P, Bohnsack MT - RNA Biol (2016)

Bottom Line: We identify the orphan G-patch protein Cmg1 (YLR271W) as a novel cofactor of Prp43 and show that it stimulates the RNA binding and ATPase activity of the helicase.Interestingly, Cmg1 localizes to the cytoplasm and to the intermembrane space of mitochondria and its overexpression promotes apoptosis.Furthermore, our data reveal that different G-patch protein cofactors compete for interaction with Prp43.

View Article: PubMed Central - PubMed

Affiliation: a Institute for Molecular Biology, Georg-August University , Goettingen , Germany.

ABSTRACT
A rapidly increasing number of RNA helicases are implicated in several distinct cellular processes, however, the modes of regulation of multifunctional RNA helicases and their recruitment to different target complexes have remained unknown. Here, we show that the distribution of the multifunctional DEAH-box RNA helicase Prp43 between its diverse cellular functions can be regulated by the interplay of its G-patch protein cofactors. We identify the orphan G-patch protein Cmg1 (YLR271W) as a novel cofactor of Prp43 and show that it stimulates the RNA binding and ATPase activity of the helicase. Interestingly, Cmg1 localizes to the cytoplasm and to the intermembrane space of mitochondria and its overexpression promotes apoptosis. Furthermore, our data reveal that different G-patch protein cofactors compete for interaction with Prp43. Changes in the expression levels of Prp43-interacting G-patch proteins modulate the cellular localization of Prp43 and G-patch protein overexpression causes accumulation of the helicase in the cytoplasm or nucleoplasm. Overexpression of several G-patch proteins also leads to defects in ribosome biogenesis that are consistent with withdrawal of the helicase from this pathway. Together, these findings suggest that the availability of cofactors and the sequestering of the helicase are means to regulate the activity of multifunctional RNA helicases and their distribution between different cellular processes.

No MeSH data available.


Related in: MedlinePlus

Scheme of the localisations of Prp43 and its G-patch protein cofactors. Prp43 is largely localized in nucleoli (No) where it is involved in ribosome synthesis and likely interacts with Pxr1/Gno1 and Sqs1/Pfa1. Prp43 is also found in nucleoplasm, where it acts in splicing with Spp382/Ntr1, and it is present in the cytoplasm, possibly binding Sqs1 or Cmg1. Dotted arrows indicate the exchange of Prp43 between its different cofactors.
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f0007: Scheme of the localisations of Prp43 and its G-patch protein cofactors. Prp43 is largely localized in nucleoli (No) where it is involved in ribosome synthesis and likely interacts with Pxr1/Gno1 and Sqs1/Pfa1. Prp43 is also found in nucleoplasm, where it acts in splicing with Spp382/Ntr1, and it is present in the cytoplasm, possibly binding Sqs1 or Cmg1. Dotted arrows indicate the exchange of Prp43 between its different cofactors.

Mentions: A growing number of RNA helicases have recently been shown to act in several different pathways, indicating that the “one enzyme – one function” model does not apply for these proteins. However, little is known about their interaction partners and it has remained unclear how the distribution of such multifunctional RNA helicases between individual target pathways and RNA-protein complexes is regulated. Here, we show that multiple G-patch protein cofactors compete for binding of the multifunctional RNA helicase Prp43. Prp43 is mainly localized in nucleoli, where it interacts with the G-patch proteins Sqs1/Pfa1 and Pxr1/Gno1 in ribosome biogenesis (Fig. 7). In addition, Prp43 acts in pre-mRNA splicing together with Spp382/Ntr1 in the nucleoplasm and has been suggested to shuttle to the cytoplasm with Sqs1 on pre-40S complexes. Interestingly, changes in the levels of its G-patch protein cofactors modulate the cellular localization of Prp43, suggesting a model in which cofactor competition regulates the distribution of the multifunctional RNA helicase between different pathways. This competition can even occur between different functions in the same pathway, as illustrated here in the case of ribosome biogenesis, where Sqs1 and Pxr1 compete for Prp43 interaction. The overexpression of either Sqs1 or Pxr1 results in redirection of Prp43 to complexes containing the overexpressed cofactor, likely leading to withdrawal of Prp43 from other pre-ribosomal intermediates, preventing its function in their maturation. Indeed, redistribution of Prp43 affects its activity in ribosome biogenesis and leads to defects in the processing of rRNA precursors. Interestingly, these results are supported by an independent report that also demonstrates defects in splicing upon overexpression of the G-patch protein Sqs1,42 indicating that sequestering of Prp43 to the cytoplasm by Sqs1 causes defects in mRNA maturation as well as in ribosome biogenesis. The strong defects observed upon overexpression of Sqs1 also further support the suggestion that Prp43 and Sqs1 shuttle to the cytoplasm, where they stimulate the final processing of the 18S rRNA by the endonuclease Nob135 and that this might involve a larger fraction of Prp43 than previously anticipated.Figure 7.


Protein cofactor competition regulates the action of a multifunctional RNA helicase in different pathways.

Heininger AU, Hackert P, Andreou AZ, Boon KL, Memet I, Prior M, Clancy A, Schmidt B, Urlaub H, Schleiff E, Sloan KE, Deckers M, Lührmann R, Enderlein J, Klostermeier D, Rehling P, Bohnsack MT - RNA Biol (2016)

Scheme of the localisations of Prp43 and its G-patch protein cofactors. Prp43 is largely localized in nucleoli (No) where it is involved in ribosome synthesis and likely interacts with Pxr1/Gno1 and Sqs1/Pfa1. Prp43 is also found in nucleoplasm, where it acts in splicing with Spp382/Ntr1, and it is present in the cytoplasm, possibly binding Sqs1 or Cmg1. Dotted arrows indicate the exchange of Prp43 between its different cofactors.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4829300&req=5

f0007: Scheme of the localisations of Prp43 and its G-patch protein cofactors. Prp43 is largely localized in nucleoli (No) where it is involved in ribosome synthesis and likely interacts with Pxr1/Gno1 and Sqs1/Pfa1. Prp43 is also found in nucleoplasm, where it acts in splicing with Spp382/Ntr1, and it is present in the cytoplasm, possibly binding Sqs1 or Cmg1. Dotted arrows indicate the exchange of Prp43 between its different cofactors.
Mentions: A growing number of RNA helicases have recently been shown to act in several different pathways, indicating that the “one enzyme – one function” model does not apply for these proteins. However, little is known about their interaction partners and it has remained unclear how the distribution of such multifunctional RNA helicases between individual target pathways and RNA-protein complexes is regulated. Here, we show that multiple G-patch protein cofactors compete for binding of the multifunctional RNA helicase Prp43. Prp43 is mainly localized in nucleoli, where it interacts with the G-patch proteins Sqs1/Pfa1 and Pxr1/Gno1 in ribosome biogenesis (Fig. 7). In addition, Prp43 acts in pre-mRNA splicing together with Spp382/Ntr1 in the nucleoplasm and has been suggested to shuttle to the cytoplasm with Sqs1 on pre-40S complexes. Interestingly, changes in the levels of its G-patch protein cofactors modulate the cellular localization of Prp43, suggesting a model in which cofactor competition regulates the distribution of the multifunctional RNA helicase between different pathways. This competition can even occur between different functions in the same pathway, as illustrated here in the case of ribosome biogenesis, where Sqs1 and Pxr1 compete for Prp43 interaction. The overexpression of either Sqs1 or Pxr1 results in redirection of Prp43 to complexes containing the overexpressed cofactor, likely leading to withdrawal of Prp43 from other pre-ribosomal intermediates, preventing its function in their maturation. Indeed, redistribution of Prp43 affects its activity in ribosome biogenesis and leads to defects in the processing of rRNA precursors. Interestingly, these results are supported by an independent report that also demonstrates defects in splicing upon overexpression of the G-patch protein Sqs1,42 indicating that sequestering of Prp43 to the cytoplasm by Sqs1 causes defects in mRNA maturation as well as in ribosome biogenesis. The strong defects observed upon overexpression of Sqs1 also further support the suggestion that Prp43 and Sqs1 shuttle to the cytoplasm, where they stimulate the final processing of the 18S rRNA by the endonuclease Nob135 and that this might involve a larger fraction of Prp43 than previously anticipated.Figure 7.

Bottom Line: We identify the orphan G-patch protein Cmg1 (YLR271W) as a novel cofactor of Prp43 and show that it stimulates the RNA binding and ATPase activity of the helicase.Interestingly, Cmg1 localizes to the cytoplasm and to the intermembrane space of mitochondria and its overexpression promotes apoptosis.Furthermore, our data reveal that different G-patch protein cofactors compete for interaction with Prp43.

View Article: PubMed Central - PubMed

Affiliation: a Institute for Molecular Biology, Georg-August University , Goettingen , Germany.

ABSTRACT
A rapidly increasing number of RNA helicases are implicated in several distinct cellular processes, however, the modes of regulation of multifunctional RNA helicases and their recruitment to different target complexes have remained unknown. Here, we show that the distribution of the multifunctional DEAH-box RNA helicase Prp43 between its diverse cellular functions can be regulated by the interplay of its G-patch protein cofactors. We identify the orphan G-patch protein Cmg1 (YLR271W) as a novel cofactor of Prp43 and show that it stimulates the RNA binding and ATPase activity of the helicase. Interestingly, Cmg1 localizes to the cytoplasm and to the intermembrane space of mitochondria and its overexpression promotes apoptosis. Furthermore, our data reveal that different G-patch protein cofactors compete for interaction with Prp43. Changes in the expression levels of Prp43-interacting G-patch proteins modulate the cellular localization of Prp43 and G-patch protein overexpression causes accumulation of the helicase in the cytoplasm or nucleoplasm. Overexpression of several G-patch proteins also leads to defects in ribosome biogenesis that are consistent with withdrawal of the helicase from this pathway. Together, these findings suggest that the availability of cofactors and the sequestering of the helicase are means to regulate the activity of multifunctional RNA helicases and their distribution between different cellular processes.

No MeSH data available.


Related in: MedlinePlus