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bioRxiv · 10.1101/2023.11.18.567481

Guanylate cyclase activity of TIR1/AFB auxin receptorsin rapid auxin responses

Qi, L.·Kwiatkowski, M.·Kulich, I.·Chen, H.·Gao, Y.·Yun, P.·Li, L.·Shabala, S.·Farmer, E.·Jaworski, K.·Friml, J.
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Abstract

The plant hormone auxin is perceived by TIR1/AFB receptors, which mediate transcriptional reprogramming via a ubiquitination- and cAMP-dependent mechanism. Same receptors mediate also rapid, non-transcriptional growth responses that are mechanistically less well understood. Here, we demonstrate that TIR1/AFB receptors possess not only adenylate cyclase but also guanylate cyclase activity. Auxin perception independently activates cAMP and cGMP production by TIR1/AFBs in vitro and elevates both cAMP and cGMP levels in planta. Genetic and synthetic biology approaches revealed that AFB1 guanylate cyclase activity is required for the rapid cytosolic Ca2+ transients and root growth inhibition. This unprecedented combination of adenylate and guanylate cyclase activities within a single hormone receptor establishes a new paradigm for how one perception mechanism can mediate distinct downstream responses. One-Sentence SummaryTIR1/AFB auxin receptors possess both, adenylate and guanylate cyclase activities, mediating transcriptional reprogramming and rapid Ca2+-dependent growth responses, respectively.

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Qi, L., Kwiatkowski, M., Kulich, I., Chen, H., Gao, Y., Yun, P., Li, L., Shabala, S., Farmer, E., Jaworski, K., Friml, J.. 2023-11-18. Guanylate cyclase activity of TIR1/AFB auxin receptorsin rapid auxin responses. https://doi.org/10.1101/2023.11.18.567481

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