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David Bui Richard Lauhead Randall Mello Michelle Tran Team E
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Why is it important to have this kit? Disregulation of the SUMO pathway has been linked to diseases including ovarian carcinoma, melanoma, and lung adenocarcinoma. (Mo and Moschos 2005) http://www.biochem.mpg.de/jentsch/Mueller.html Forster Resonance Energy Transfer Energy transfer between donor and acceptor fluorophores at the distance of 2-10 nm (Dos Remedios and Moens 1995) Engineered CFP (Cypet) and YFP (Ypet) genetically engineered to proteins SUMO-1 and E2 Conjugating enzyme Ubc9 of the Sumoylation pathway
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Develop a high throughput screening kit based on FRET that allows for detection of protein-protein (SUMO1-UBC9) interactions Allows for basic screening of inhibitors that alter binding between target proteins Combine two target proteins at a specific concentration ratio If proteins do not bind FRET does not occur If proteins do bind energy transfer will occur FRET picture adapted from www.nature.com/.../v4/n7/fig_tab/nrm1153_F2.html Develop a process to optimize a HTS kit Meet NIH standards
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Protein Expression Cypet-SUMO1, Ypet-Ubc9, Ubc9 2 weeks Protein Purification Ni-NTA Column Chromatography/Dialysis 2 weeks Protein Characterization Bradford assay, fluorescence characterization, SDS PAGE Protein Gel etc.. 3 weeks Protein Expression Optimization IPTG, 7-16 hour growth/expression 2 weeks Kit Design/ Quality Control Lyophilization, Oxidation, and Stability studies with urea 3 weeks Z Factor Studies for HTS FRET Ratio optimization Cypet-SUMO1/Ypet-Ubc9 Concentration optimization 3 weeks Ubc9 Mock Inhibitor Studies Ubc9+Ypet-Ubc9/ Ubc9+Cypet-SUMO1/Ypet- Ubc9+Cypet-SUMO1 concentration experiments 2 weeks Inhibitor Kd Modeling Effects of Inhibitor Kd on Bound Protein, Kdapp equations 2 weeks
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Determine sensitivity of the FlexStation II RESULTS: As low as 25 ng, but useable around 500 ng of fluorescent protein Determine method for characterizing Fluorescent protein concentration RESULTS: Bradford Assay and Fluorescent Standard Curves Determine if purification affects the assay and an optimal purification protocol RESULTS: Purity has no effect and Protocol 1 was chosen Lyophilization Studies RESULTS: Does not effect protein stability
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CYpet and Ypet were engineered as FRET pairs UBC9 was identified as a protein that binds to SUMO1 in the SUMO pathway. Kd between SUMO1 and UBC9 was determined by BIACORE(SPR) as 0.75 FRET was determined to work between CYpet-SUMO1(CS1) and Ypet-UBC9(YU9)
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Innoculate 1:50 Protocol 1 Protocol 2 Protocol 3 Protocol 4 IPTG added when OD =.4.5 mM.1 mM1mM.5 mM Time Incubated 3 hours16 hours3 hours16 hours Incubation Temp. o C 37253725 Protocol 2 works the best
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The Z’ Factor is a characteristic parameter for the quality of the assay, without intervention of test compounds C+, C+ :the mean and standard deviation of positive hits C-, C- :the mean and standard deviation of negative hits Well # Test Value Plot of Positive hits and negative hits Z < 0.0 ; Not usable Assay 0.0 < Z < 0.5 ; A Doable Assay 0.5 < Z < 1.0 ; An Excellent Assay Z= 1.0 ; Ideal Assay Ji-Hu Zhang et. al.
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Ratio: Use 10 wells for each test of positive and negative hits Run the tests at different ratios of CS1 to YU9 Ratio of 1:2.8 is useable ratio of Cypet-SUMO1 to Ypet-UBC9
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Protein amount Use ten wells for each run of positive and negative hits Run the test with differing amount of CS1 and YU9 and a constant ratio of 1 : 2.8 Useable protein amount selected is 0.25 M CS1 and 0.7 M YU9
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How long does the assay need to incubate before it is measureable? This shows that this assay is usable after incubating only 5 minutes
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Equations for K d in presence of an Inhibitor: K d of inhibitor [CS1YU9] M Effects of Inhibitor Kd on Bound Protein max Thanks to high [inhibitor] this assay will detect inhibitors with high K d values
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Designed a set of experiments to optimize the steps from protein expression to binding assays in a HTS format Demonstrated that purity of proteins has no effect on the FRET ratio Demonstrated that lyophilization is not necessary in kit design over non-lyophilized protein
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FRET-based HTS binding assay meets Z’-Factor signal requirements of >0.5 at a FRET Ratio of 1:2.8, at concentrations of 0.25 and 0.70 uM per well for Cypet-SUMO1 and Ypet-Ubc9, and over a 60 minute period BRET Technology: Luciferase reporter enzyme used at 3 uM per well in one 384-well HTS study to reach a Z’-Factor over 0.5 ( Molecular Biology in Medicinal Chemistry Volume 21,pg.20. Wiley-VCH 2004) Kocan, Martina, Heng B. See, and Ruth M. Seeber. "Demonstration of Improvements to the Bioluminescence Resonance Energy Transfer (BRET) Technology for the Monitoring of G Protein–Coupled Receptors in Live Cells." Journal of Biomolecular Screening (2008). Society of Biomolcecular Sciences.
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Investigate mock inhibitor to incorporate with kit Allows for kit users to compare and analyze other positive hits Optimize protein expression Engineer CYpet-SUMO1 and Ypet-Ubc9 to have an E. coli secretion sequence Package materials and create an instructions manual to bring kit to a commercial level
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Dr. Jiayu Liao Vipul Madahar Yang Song Gokul Upadhyayula Thank you!!!! Jerome Schultz
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www.engr.ucr.edu/~mitran
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