Biology subjects

Ordureau, A.

Publications and source records attributed to Ordureau, A..

3 recordsLinked to original sources

bioRxiv2022

NAK associated protein 1 is required to activate Tank binding kinase 1 to regulate mitosis

Subcellular location and activation of Tank Binding Kinase 1 (TBK1) govern precise progression through mitosis. Either loss of activated TBK1 or its sequestration from the centrosomes causes error in mitosis and growth defects. Yet, what regulates its recruitment and activation on the centrosomes is unknown. We identified that NAK Associated Protein 1 (NAP1) is essential for mitosis which binds to TBK1 on the centrosomes to activate it. Loss of NAP1 causes several mitotic and cytokinetic defects due to inactivation of TBK1. Our quantitative phosphoproteomics identified numerous TBK1 substrates that are not only confined to the centrosomes but also are associated with microtubules. Substrate motifs analysis indicates that TBK1 acts upstream of other essential cell cycle kinases like Aurora and PAK kinases. We also identified NAP1 as a TBK1 substrate at S318 promoting its degradation by ubiquitin proteasomal system acting as a negative regulatory step. These data uncover an important distinct function for the NAP1-TBK1 complex during cell division.

cell biology↗

bioRxiv2021

Vaccinia E5 is a major inhibitor of the DNA sensor cGAS

The DNA sensor cyclic GMP-AMP synthase (cGAS) is critical in host antiviral immunity. Vaccinia virus (VACV) is a large cytoplasmic DNA virus that belongs to the poxvirus family. How vaccinia virus antagonizes the cGAS-mediated cytosolic DNA-sensing pathway is largely unknown. In this study, we screened 82 vaccinia viral genes to identify potential viral inhibitors of the cGAS/Stimulator of interferon gene (STING) pathway. We discovered that vaccinia E5 is a virulence factor and a major inhibitor of cGAS that elicits proteasome-dependent cGAS degradation. E5 localizes to the cytoplasm and nuclei of infected cells. Cytosolic E5 triggers K48-linked ubiquitination of cGAS and proteasome-dependent degradation via interacting with cGAS. E5 itself also undergoes ubiquitination and degradation. Deleting the E5R gene from the Modified vaccinia virus Ankara (MVA) genome strongly induces type I IFN production by dendritic cells (DCs) and promotes DC maturation, thereby improving the immunogenicity of the viral vector.

microbiology↗

bioRxiv2021

Global ubiquitylation analysis of mitochondria in primary neurons identifies physiological Parkin targets following activation of PINK1

Autosomal recessive mutations in PINK1 and Parkin cause Parkinsons disease. How activation of PINK1 and Parkin leads to elimination of damaged mitochondria by mitophagy is largely based on cell culture studies with few molecular studies in neurons. Herein we have undertaken a global proteomic-analysis of mitochondria from mouse neurons to identify ubiquitylated substrates of endogenous Parkin activation. Comparative analysis with human iNeuron datasets revealed a subset of 49 PINK1-dependent diGLY sites upregulated upon mitochondrial depolarisation in 22 proteins conserved across mouse and human systems. These proteins were exclusively localised at the mitochondrial outer membrane (MOM) including, CISD1, CPT1, ACSL1, and FAM213A. We demonstrate that these proteins can be directly ubiquitylated by Parkin in vitro. We also provide evidence for a subset of cytoplasmic proteins recruited to mitochondria that undergo PINK1 and Parkin independent ubiquitylation including SNX3, CAMK2 and CAMK2{beta} indicating the presence of alternate ubiquitin E3 ligase pathways that are activated by mitochondrial depolarisation in neurons. Finally we have developed an online resource to visualise mitochondrial ubiquitin sites in neurons and search for ubiquitin components recruited to mitochondria upon mitochondrial depolarisation, MitoNUb. This analysis will aid in future studies to understand Parkin activation in neuronal subtypes. Our findings also suggest that monitoring ubiquitylation status of the 22 identified MOM proteins may represent robust biomarkers for PINK1 and Parkin activity in vivo.

biochemistry↗