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The maize OST1 kinase homolog phosphorylates and regulates the maize SNAC1-type transcription factor.

Vilela B, Moreno-Cortés A, Rabissi A, Leung J, Pagès M, Lumbreras V - PLoS ONE (2013)

Bottom Line: Furthermore, we have identified the transcription factor, ZmSNAC1, which is directly phosphorylated by ZmOST1 with implications on its localization and protein stability.Interestingly, ZmSNAC1 binds to the ABA-box of ZmOST1, which is conserved in SnRK2s activated by ABA and is part of the contact site for the negative-regulating clade A PP2C phosphatases.Taken together, our results indicate that ZmSNAC1 is a substrate of ZmOST1 and delineate a novel osmotic stress transcriptional pathway in maize.

View Article: PubMed Central - PubMed

Affiliation: Centre for Research in Agricultural Genomics, Bellaterra, Cerdanyola del Vallés, Spain.

ABSTRACT
The Arabidopsis kinase OPEN STOMATA 1 (OST1) plays a key role in regulating drought stress signalling, particularly stomatal closure. We have identified and investigated the functions of the OST1 ortholog in Z. mays (ZmOST1). Ectopic expression of ZmOST1 in the Arabidopsis ost1 mutant restores the stomatal closure phenotype in response to drought. Furthermore, we have identified the transcription factor, ZmSNAC1, which is directly phosphorylated by ZmOST1 with implications on its localization and protein stability. Interestingly, ZmSNAC1 binds to the ABA-box of ZmOST1, which is conserved in SnRK2s activated by ABA and is part of the contact site for the negative-regulating clade A PP2C phosphatases. Taken together, our results indicate that ZmSNAC1 is a substrate of ZmOST1 and delineate a novel osmotic stress transcriptional pathway in maize.

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ZmOST1 alters ZmSNAC1 protein stability under ABA treatment. ZmSNAC1 phosphorylation and protein stability was analyzed by bi-dimensional gel electrophoresis followed by western blot.(A) Arabidopsis ost1-2 mutant and (B) Maize B73 protoplasts transfected with ZmSNAC1-GFP alone or with ZmOST1-HA. Upper western blot corresponds to control situations the lower corresponds to 30 min 10 µM ABA treatment.
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pone-0058105-g007: ZmOST1 alters ZmSNAC1 protein stability under ABA treatment. ZmSNAC1 phosphorylation and protein stability was analyzed by bi-dimensional gel electrophoresis followed by western blot.(A) Arabidopsis ost1-2 mutant and (B) Maize B73 protoplasts transfected with ZmSNAC1-GFP alone or with ZmOST1-HA. Upper western blot corresponds to control situations the lower corresponds to 30 min 10 µM ABA treatment.

Mentions: In order to better determine the in vivo phosphorylation and protein stability of SNAC1 we performed Bi-dimensional SDS-PAGE experiments comparing ZmSNAC1 protein fused to GFP using the Arabidopsis and maize protoplast systems. Even though in this experiment we were not able to clearly detect any protein shift that is consistent with a phosphorylation, the quantity and abundance of ZmSNAC1 spots is clearly affected by ABA treatment when ZmOST1 is present (Figure 7). While in the ost1-2 protoplasts ZmSNAC1 quantity is unaffected by ABA, when protoplasts are co-transformed with ZmOST1, a clear reduction of the most acidic ZmSNAC1 spots is clear (Figure 7A). When repeating the experiment in maize protoplasts we were able to observe the same degradation of ZmSNAC1 under ABA treatment (Figure 7B). These results seem to indicate that ZmOST1 activity has an effect on ZmSNAC1 stability.


The maize OST1 kinase homolog phosphorylates and regulates the maize SNAC1-type transcription factor.

Vilela B, Moreno-Cortés A, Rabissi A, Leung J, Pagès M, Lumbreras V - PLoS ONE (2013)

ZmOST1 alters ZmSNAC1 protein stability under ABA treatment. ZmSNAC1 phosphorylation and protein stability was analyzed by bi-dimensional gel electrophoresis followed by western blot.(A) Arabidopsis ost1-2 mutant and (B) Maize B73 protoplasts transfected with ZmSNAC1-GFP alone or with ZmOST1-HA. Upper western blot corresponds to control situations the lower corresponds to 30 min 10 µM ABA treatment.
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Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3585266&req=5

pone-0058105-g007: ZmOST1 alters ZmSNAC1 protein stability under ABA treatment. ZmSNAC1 phosphorylation and protein stability was analyzed by bi-dimensional gel electrophoresis followed by western blot.(A) Arabidopsis ost1-2 mutant and (B) Maize B73 protoplasts transfected with ZmSNAC1-GFP alone or with ZmOST1-HA. Upper western blot corresponds to control situations the lower corresponds to 30 min 10 µM ABA treatment.
Mentions: In order to better determine the in vivo phosphorylation and protein stability of SNAC1 we performed Bi-dimensional SDS-PAGE experiments comparing ZmSNAC1 protein fused to GFP using the Arabidopsis and maize protoplast systems. Even though in this experiment we were not able to clearly detect any protein shift that is consistent with a phosphorylation, the quantity and abundance of ZmSNAC1 spots is clearly affected by ABA treatment when ZmOST1 is present (Figure 7). While in the ost1-2 protoplasts ZmSNAC1 quantity is unaffected by ABA, when protoplasts are co-transformed with ZmOST1, a clear reduction of the most acidic ZmSNAC1 spots is clear (Figure 7A). When repeating the experiment in maize protoplasts we were able to observe the same degradation of ZmSNAC1 under ABA treatment (Figure 7B). These results seem to indicate that ZmOST1 activity has an effect on ZmSNAC1 stability.

Bottom Line: Furthermore, we have identified the transcription factor, ZmSNAC1, which is directly phosphorylated by ZmOST1 with implications on its localization and protein stability.Interestingly, ZmSNAC1 binds to the ABA-box of ZmOST1, which is conserved in SnRK2s activated by ABA and is part of the contact site for the negative-regulating clade A PP2C phosphatases.Taken together, our results indicate that ZmSNAC1 is a substrate of ZmOST1 and delineate a novel osmotic stress transcriptional pathway in maize.

View Article: PubMed Central - PubMed

Affiliation: Centre for Research in Agricultural Genomics, Bellaterra, Cerdanyola del Vallés, Spain.

ABSTRACT
The Arabidopsis kinase OPEN STOMATA 1 (OST1) plays a key role in regulating drought stress signalling, particularly stomatal closure. We have identified and investigated the functions of the OST1 ortholog in Z. mays (ZmOST1). Ectopic expression of ZmOST1 in the Arabidopsis ost1 mutant restores the stomatal closure phenotype in response to drought. Furthermore, we have identified the transcription factor, ZmSNAC1, which is directly phosphorylated by ZmOST1 with implications on its localization and protein stability. Interestingly, ZmSNAC1 binds to the ABA-box of ZmOST1, which is conserved in SnRK2s activated by ABA and is part of the contact site for the negative-regulating clade A PP2C phosphatases. Taken together, our results indicate that ZmSNAC1 is a substrate of ZmOST1 and delineate a novel osmotic stress transcriptional pathway in maize.

Show MeSH
Related in: MedlinePlus