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bioRxiv · 10.1101/783373

Crystal structure of human PACRG in complex with MEIG1

Khan, N.·Pelletier, D.·Veyron, S.·Croteau, N.·Ichikawa, M.·Black, C.·Khalifa, A. A. Z.·Chaaban, S.·Kurinov, I.·Brouhard, G.·Bui, K. H.·Trempe, J.-F.
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Abstract

In human, the Parkin Co-Regulated Gene (PACRG) shares a bidirectional promoter with Parkin, a gene involved in Parkinsons disease, mitochondrial quality control and inflammation. The PACRG protein is essential to the formation of the inner junction between doublet microtubules of the axoneme, a structure found in flagella and cilia. PACRG interacts with tubulin as well as the meiosis expressed gene 1 (MEIG1) protein, which is essential for spermiogenesis in mice. However, the 3D structure of human PACRG is unknown. Here, we report the crystal structure of the C-terminal domain of human PACRG in complex with MEIG1 at 2.1 [A] resolution. PACRG adopts an -helical structure with a loop insertion that mediates a conserved network of interactions with MEIG1. Using the cryo-electron tomography structure of the axonemal doublet microtubule from the flagellated protozoan Chlamydomonas reinhardtii, we generate a model of a mammalian microtubule doublet inner junction, which reveals how PACRG interacts with tubulin subunits in both the A- and B-tubules. Furthermore, the model shows that MEIG1 interacts with {beta}-tubulin on the outer surface of the B-tubule, facing towards the central pair of the axoneme. We also model the PACRG-like protein (PACRGL), a homolog of PACRG with potential roles in microtubule remodelling and axonemal inner junction formation. Finally, we explore the evolution of the PACRG and Parkin head-to-head gene structure and analyze the tissue distribution of their transcripts. Our work establishes a framework to assess the function of the PACRG family of proteins and its adaptor proteins in the function of motile and non-motile cilia.

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Khan, N., Pelletier, D., Veyron, S., Croteau, N., Ichikawa, M., Black, C., Khalifa, A. A. Z., Chaaban, S., Kurinov, I., Brouhard, G., Bui, K. H., Trempe, J.-F.. 2019-09-27. Crystal structure of human PACRG in complex with MEIG1. https://doi.org/10.1101/783373

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