Carboxypeptidase B-Assisted Charge-Based Fractional Diagonal Chromatography for Deep Screening of C-Terminome

Anal Chem. 2020 Jun 16;92(12):8005-8009. doi: 10.1021/acs.analchem.0c00762. Epub 2020 May 28.

Abstract

The determination of protein C-termini is of great significance for protein function annotation and proteolysis research. However, the progress of C-terminomics is still far behind its counterpart, N-terminomics, because of the low reactivity of the carboxyl group. Herein, we developed a negative selection strategy, termed carboxypeptidase B-assisted charge-based fractional diagonal chromatography (CPB-ChaFRADIC), to achieve a global C-terminome analysis. The highly reactive carboxypeptidase B cleavage was utilized to reduce the charge state of non-C-terminal peptides. Together with high-performance charge-based fractional diagonal chromatography, the C-terminal peptides could be isolated. Such a strategy was applied for profiling C-termini from Escherichia coli cell lysates and 441 canonical C-termini and 510 neo-C-termini originating from proteolytic processing were identified. These findings represent 2-fold and 5.8-fold that of identified C-termini via direct analysis, respectively. Using parallel digestion with trypsin and LysC, such a strategy enabled the identification of 604 canonical C-termini and 818 neo-C-termini, representing the largest C-terminome data set of E. coli, and no deficiency in His/Lys/Arg-containing C-terminal peptides was observed. The presented CPB-ChaFRADIC strategy is therefore a highly efficient and unbiased strategy for large-scale C-terminome analysis. Furthermore, using the CPB-ChaFRADIC strategy, we identified 107 cleavage sites and 102 substrates of caspase-3 in Jurkat cells, demonstrating that the CPB-ChaFRADIC strategy shows great promise in promoting proteolysis research. Data are available via ProteomeXchange with identifier PXD018520.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Carboxypeptidase B / metabolism*
  • Chromatography, Liquid
  • Escherichia coli / enzymology
  • Humans
  • Peptides / chemistry
  • Peptides / metabolism
  • Protein C / analysis*
  • Protein C / metabolism
  • Tandem Mass Spectrometry

Substances

  • Peptides
  • Protein C
  • Carboxypeptidase B