Project description:Proximity-dependent labelling (PL) methods are based on promiscuous labeling enzymes that produce reactive molecules that covalently bind neighbor proteins. Labeled proteins can be then purified and identified using affinity-purification coupled to mass spectrometry methods39. Proximity-dependent biotin identification (BioID)40 uses a promiscuously active Escherichia coli biotin ligase (BirA*) generated by a point mutation (R118G) to biotinylate lysines in nearby proteins within an estimated range of 10 nm41. By fusing BirA* to specific proteins, BioID efficiently identifies interactors at physiological levels in living cells42, 43. It has been extensively used in the Ub field, for instance, to identify substrates of E3 ligases44-46. Recently, a more efficient version of BioID, termed TurboID, has been developed47. TurboID can proximally biotinylate in 10 minutes to the same levels as BioID does in 18 hours, thus making it more suitable for transient protein-protein interaction (PPI) detection. Several studies have developed split-versions and applied “protein fragment complementation” (PCA) to BioID and TurboID, where proximal biotinylation is dependent on the proximity of the fusion partners, opening new opportunities for spatial and temporal identification of complex-dependent interactomes48-50. To study how SUMOylation and SUMO-SIM interactions can lead to other roles and fates for particular substrates poses particular challenges. SUMOylation occurs transiently and often in a small percentage of a given substrate. Modified proteins can be readily deSUMOylated and SUMO can be recycled and passed to other substrates. SUMO-SIM interactions are also difficult to analyze due to their weak affinity (Kd ranging from 1-100 µM). To overcome those technical issues, we developed SUMO-ID, a new strategy based on Split-TurboID to identify SUMO- interactors of specific substrates dependent on SUMO conjugation or interaction. Using PML as a model, we demonstrate that SUMO-ID can enrich for factors that depend on PML-SUMO interaction. Importantly, those are represented among proximal interactors of PML identified using full-length TurboID. We also applied SUMO-ID to a less-characterized SUMO substrate, Spalt like transcription factor 1 (SALL1), and identified both known and novel interactors that depend on intact SUMOylation sites in SALL1. SUMO-ID is thus a powerful tool to study transient and dynamic SUMO-dependent interaction events.

Project description:Signal transduction by the NF-kappaB pathway is a key regulator of a host of cellular responses to extracellular and intracellular messages. The NEMO adaptor protein lies at the top of this pathway and serves as a molecular conduit, connecting signals transmitted from upstream sensors to the downstream NF-kappaB transcription factor and subsequent gene activation. The position of NEMO within this pathway makes it an attractive target from which to search for new proteins that link NF-kappaB signaling to additional pathways and upstream effectors. In this work, we have used protein microarrays to identify novel NEMO interactors. A total of 112 protein interactors were identified, with the most statistically significant hit being the canonical NEMO interactor IKKbeta, with IKKalpha also being identified. Of the novel interactors, more than 30% were kinases, while at least 25% were involved in signal transduction. Binding of NEMO to several interactors, including CALB1, CDK2, SAG, SENP2 and SYT1, was confirmed using GST pulldown assays and coimmunoprecipitation, validating the initial screening approach. Overexpression of CALB1, CDK2 and SAG was found to stimulate transcriptional activation by NF-kappaB, while SYT1 overexpression repressed TNFalpha-dependent NF-kappaB transcriptional activation in human embryonic kidney cells. Corresponding with this finding, RNA silencing of CDK2, SAG and SENP2 reduced NF-kappaB transcriptional activation, supporting a positive role for these proteins in the NF-kappaB pathway. The identification of a host of new NEMO interactors opens up new research opportunities to improve understanding of this essential cell signaling pathway. For microarray screening, Invitrogen Protoarray v4.0 protein microarrays were used. Human NEMO expressed as a C-terminal GST fusion was purified from E. coli lysates and labelled with biotin. NEMO or biotinylated GST were applied to the microarrays and binding partners detected using streptavidin-Alexa Fluor 647. Significant interactors on both arrays were detected using Invitrogen Protoarray Prospector software and a Z-score cutoff of 3.0. Following subtraction of interactors present on the GST control array, a final set of significant NEMO interactors was derived. Full experimental details are supplied in Fenner, B. J., Scannell, M. & Prehn, J. H. M. (2010). Expanding the substantial interactome of NEMO using protein microarrays. PLoS ONE (in press).

			Action	DRS
	20210917_Bio1014_01_120K_clm187_WC18_65cm_HCD_OT_AGtrap_val50_11to32B_180m_1ul_01.msf	Msf
	20210917_Bio1014_01_120K_clm187_WC18_65cm_HCD_OT_AGtrap_val50_11to32B_180m_1ul_01.raw	Raw
	20210917_Bio1014_02_120K_clm187_WC18_65cm_HCD_OT_AGtrap_val50_11to32B_180m_1ul_01.msf	Msf
	20210917_Bio1014_02_120K_clm187_WC18_65cm_HCD_OT_AGtrap_val50_11to32B_180m_1ul_01.raw	Raw
	20210917_Bio1014_03_120K_clm187_WC18_65cm_HCD_OT_AGtrap_val50_11to32B_180m_1ul_01.msf	Msf

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BioID study of the PHB2 interactome in Schwann cells and how it changes depending on neuronal signals

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