Refinements of LC-MS/MS Spectral Counting Statistics Improve Quantification of Low Abundance Proteins

Sci Rep. 2019 Sep 20;9(1):13653. doi: 10.1038/s41598-019-49665-1.

Abstract

Mass spectrometry-based spectral count has been a common choice of label-free proteome quantification due to the simplicity for the sample preparation and data generation. The discriminatory nature of spectral count in the MS data-dependent acquisition, however, inherently introduces the spectral count variation for low-abundance proteins in multiplicative LC-MS/MS analysis, which hampers sensitive proteome quantification. As many low-abundance proteins play important roles in cellular processes, deducing low-abundance proteins in a quantitatively reliable manner greatly expands the depth of biological insights. Here, we implemented the Moment Adjusted Imputation error model in the spectral count refinement as a post PLGEM-STN for improving sensitivity for quantitation of low-abundance proteins by reducing spectral count variability. The statistical framework, automated spectral count refinement by integrating the two statistical tools, was tested with LC-MS/MS datasets of MDA-MB468 breast cancer cells grown under normal and glucose deprivation conditions. We identified about 30% more quantifiable proteins that were found to be low-abundance proteins, which were initially filtered out by the PLGEM-STN analysis. This newly developed statistical framework provides a reliable abundance measurement of low-abundance proteins in the spectral count-based label-free proteome quantification and enabled us to detect low-abundance proteins that could be functionally important in cellular processes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Breast Neoplasms / metabolism*
  • Cell Culture Techniques
  • Cell Line, Tumor
  • Chromatography, Liquid
  • Female
  • Gene Expression Regulation, Neoplastic / drug effects
  • Gene Regulatory Networks / drug effects
  • Glucose / pharmacology*
  • Humans
  • Models, Statistical
  • Protein Interaction Maps / drug effects*
  • Proteomics / methods*
  • Tandem Mass Spectrometry

Substances

  • Glucose