MPK12 in stomatal CO2 signaling: function beyond its kinase activity

Yeh, C. -Y.; Wang, Y.-S.; Takahashi, Y.; Kuusk, K.; Paul, K.; Arjus, T.; Yadlos, O.; Schroeder, J. I.; Ilves, I.; Garcia-Sosa, A. T.; Kollist, H.

doi:10.1101/2023.01.31.526436

bioRxiv · 10.1101/2023.01.31.526436

MPK12 in stomatal CO2 signaling: function beyond its kinase activity

Yeh, C. -Y.·Wang, Y.-S.·Takahashi, Y.·Kuusk, K.·Paul, K.·Arjus, T.·Yadlos, O.·Schroeder, J. I.·Ilves, I.·Garcia-Sosa, A. T.·Kollist, H.

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Abstract

O_LIProtein phosphorylation by kinases is a major molecular switch mechanism involved in the regulation of stomatal opening and closure. Previous research defined interaction between MAP kinase 12 and Raf-like kinase HT1 as a required step for stomatal movements by changes in CO2 concentration. However, whether MPK12 kinase activity is required for regulation of CO2-induced stomatal responses warrants in depth investigation. C_LIO_LIWe apply genetic, biochemical, and structural modeling approaches to examining the non-catalytic role of MPK12 in guard cell CO2 signaling that relies on allosteric inhibition of HT1. C_LIO_LIWe show that CO2/HCO3--enhanced MPK12 interaction with HT1 is independent of its phosphor-transfer activity. By analyzing gas exchange of plant lines expressing various kinase-dead and constitutively active versions of MPK12 in a plant line where MPK12 is deleted, we confirmed that CO2-dependent stomatal responses rely on MPK12s ability to bind to HT1 but not its kinase activity. We also demonstrate that purified MPK12 and HT1 proteins form a heterodimer in the presence of CO2/HCO3- and present structural modeling that explains the MPK12:HT1 interaction interface. C_LIO_LIThese data add to the model that MPK12 kinase-activity-independent interaction with HT1 functions as a molecular switch by which stomatal guard cells sense changes in atmospheric CO2 concentration. C_LI

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Yeh, C. -Y., Wang, Y.-S., Takahashi, Y., Kuusk, K., Paul, K., Arjus, T., Yadlos, O., Schroeder, J. I., Ilves, I., Garcia-Sosa, A. T., Kollist, H.. 2023-02-01. MPK12 in stomatal CO2 signaling: function beyond its kinase activity. https://doi.org/10.1101/2023.01.31.526436

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