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Multiplex Substrate Profiling by Mass Spectrometry for Kinases as a Method for Revealing Quantitative Substrate
Nicole O Meyer1, Anthony J O'Donoghue1, Ursula Schulze-Gahmen2
1Department of Pharmaceutical Chemistry, University of California San Francisco , San Francisco, California 94158, United States.
Analytical Chemistry
|March 22, 2017
Summary
Researchers developed a novel mass spectrometry method to quantitatively profile kinase substrate specificity. This technique reveals detailed kinase activity, even with limited enzyme or sample, advancing our understanding of cellular signaling networks.
Area of Science:
- Biochemistry
- Molecular Biology
- Proteomics
Background:
- The human kinome consists of over 500 protein kinases regulating diverse cellular functions through phosphorylation.
- Understanding the extended substrate specificity of these kinases is crucial but remains incomplete for many.
- Phosphorylation events are key regulators of cellular processes, making kinase activity a central research area.
Purpose of the Study:
- To develop and validate a quantitative method for describing kinase substrate specificity.
- To characterize kinase activity using unbiased peptide libraries and mass spectrometry.
- To investigate the kinetics of specific kinase-substrate interactions, including HIV-1 Tat and P-TEFb.
Main Methods:
- Developed multiplex substrate profiling by mass spectrometry (MSP-MS) using unbiased peptide libraries.
- Employed tandem liquid chromatography-tandem mass spectrometry (LC-MS/MS) for direct phosphorylation measurement.
- Utilized label-free quantitation to determine catalytic efficiency for individual peptide substrates.
- Applied a sublibrary approach to expand sequence space for kinases like CDK1, CDK7, and CDK9.
Main Results:
- Established quantitative motifs for various kinases across the kinome, including those with and without known substrates.
- Demonstrated high sensitivity, detecting phosphorylation from nanogram quantities of immunoprecipitated material.
- Successfully localized the P-TEFb phosphorylation site and characterized Tat's stimulatory effect on P-TEFb catalytic efficiency.
- Generated quantitative substrate specificity profiles for selected kinases.
Conclusions:
- The MSP-MS method provides a sensitive and quantitative approach to define kinase substrate specificity.
- This technique enhances the understanding of kinase function and regulation in cellular signaling.
- The findings enable broader applicability in studying kinase activity, even with limited sample amounts.
- Characterization of specific kinase-P-TEFb interactions provides insights into transcriptional regulation.
