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bioRxiv · 10.1101/2021.04.13.439722

Structural and mechanistic basis for protein glutamylation by the kinase fold

Osinski, A.·Black, M.·Pawlowski, K.·Chen, Z.·Li, Y.·Tagliabracci, V. S.
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Abstract

The kinase domain transfers phosphate from ATP to substrates. However, the Legionella effector SidJ adopts a kinase fold yet catalyzes calmodulin (CaM)-dependent glutamylation to inactivate the SidE ubiquitin ligases. The structural and mechanistic basis in which the kinase domain catalyzes protein glutamylation is unknown. Here we present cryo-EM reconstructions of SidJ:CaM:SidE reaction intermediate complexes. We show that the kinase-like active site of SidJ adenylates an active site Glu in SidE resulting in the formation of a stable reaction intermediate complex. An insertion in the catalytic loop of the kinase domain positions the donor Glu near the acyl-adenylate for peptide bond formation. Our structural analysis led us to discover that the SidJ paralog SdjA is a glutamylase that differentially regulates the SidE-ligases during Legionella infection. Our results uncover the structural and mechanistic basis in which the kinase fold catalyzes non-ribosomal amino acid ligations and reveal an unappreciated level of SidE-family regulation.

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Osinski, A., Black, M., Pawlowski, K., Chen, Z., Li, Y., Tagliabracci, V. S.. 2021-04-13. Structural and mechanistic basis for protein glutamylation by the kinase fold. https://doi.org/10.1101/2021.04.13.439722

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