» Articles » PMID: 39091769

Concatemer Assisted Stoichiometry Analysis (CASA): Targeted Mass Spectrometry for Protein Quantification

Overview
Journal bioRxiv
Date 2024 Aug 2
PMID 39091769
Authors
Affiliations
Soon will be listed here.
Abstract

Large multi-protein machines are central to multiple biological processes. However, stoichiometric determination of protein complex subunits in their native states presents a significant challenge. This study addresses the limitations of current tools in accuracy and precision by introducing concatemer-assisted stoichiometry analysis (CASA). CASA leverages stable isotope-labeled concatemers and liquid chromatography parallel reaction monitoring mass spectrometry (LC-PRM-MS) to achieve robust quantification of proteins with sub-femtomole sensitivity. As a proof-of-concept, CASA was applied to study budding yeast kinetochores. Stoichiometries were determined for reconstituted kinetochore components, including the canonical H3 nucleosomes, centromeric (Cse4) nucleosomes, centromere proximal factors (Cbf1 and CBF3 complex), inner kinetochore proteins (Mif2, Ctf19 complex), and outer kinetochore proteins (KMN network). Absolute quantification by CASA revealed Cse4 as a cell-cycle controlled limiting factor for kinetochore assembly. These findings demonstrate that CASA is applicable for stoichiometry analysis of multi-protein assemblies.

References
1.
Sandall S, Severin F, McLeod I, Yates 3rd J, Oegema K, Hyman A . A Bir1-Sli15 complex connects centromeres to microtubules and is required to sense kinetochore tension. Cell. 2006; 127(6):1179-91. PMC: 2265205. DOI: 10.1016/j.cell.2006.09.049. View

2.
Lawrence R, Searle B, Llovet A, Villen J . Plug-and-play analysis of the human phosphoproteome by targeted high-resolution mass spectrometry. Nat Methods. 2016; 13(5):431-4. PMC: 5915315. DOI: 10.1038/nmeth.3811. View

3.
Westermann S, Cheeseman I, Anderson S, Yates 3rd J, Drubin D, Barnes G . Architecture of the budding yeast kinetochore reveals a conserved molecular core. J Cell Biol. 2003; 163(2):215-22. PMC: 2173538. DOI: 10.1083/jcb.200305100. View

4.
Dendooven T, Zhang Z, Yang J, McLaughlin S, Schwab J, Scheres S . Cryo-EM structure of the complete inner kinetochore of the budding yeast point centromere. Sci Adv. 2023; 9(30):eadg7480. PMC: 10381965. DOI: 10.1126/sciadv.adg7480. View

5.
WIELAND G, Hemmerich P, Koch M, Stoyan T, Hegemann J, Diekmann S . Determination of the binding constants of the centromere protein Cbf1 to all 16 centromere DNAs of Saccharomyces cerevisiae. Nucleic Acids Res. 2001; 29(5):1054-60. PMC: 29730. DOI: 10.1093/nar/29.5.1054. View