C-terminomics screen for natural substrates of cytosolic carboxypeptidase 1 reveals processing of acidic protein C termini.
Cytosolic carboxypeptidases (CCPs) constitute a new subfamily of M14 metallocarboxypeptidases associated to axonal regeneration and neuronal degeneration, among others. CCPs are deglutamylating enzymes, able to catalyze the shortening of polyglutamate side-chains and the gene-encoded C termini of tubulin, telokin, and myosin light chain kinase. The functions of these enzymes are not entirely understood, in part because of the lack of information about C-terminal protein processing in the cell and its functional implications. By means of C-terminal COFRADIC, a positional proteomics approach, we searched for cellular substrates targets of CCP1, the most relevant member of this family. We here identified seven new putative CCP1 protein substrates, including ribosomal proteins, translation factors, and high mobility group proteins. Furthermore, we showed for the first time that CCP1 processes both glutamates as well as C-terminal aspartates. The implication of these C termini in molecular interactions furthermore suggests that CCP1-mediated shortening of acidic protein tails might regulate protein-protein and protein-DNA interactions.
From the ‡Department of Medical Protein Research, VIB, B-9000 Ghent, Belgium; §Department of Biochemistry, Ghent University, B-9000 Ghent, Belgium; ¶Institute for Biotechnology and Biomedicine and Department of Biochemistry and Molecular Biology, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain.
Sebastian
S
Tanco
¶Institute for Biotechnology and Biomedicine and Department of Biochemistry and Molecular Biology, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain.
Olivia
O
Tort
From the ‡Department of Medical Protein Research, VIB, B-9000 Ghent, Belgium; §Department of Biochemistry, Ghent University, B-9000 Ghent, Belgium;
Hans
H
Demol
¶Institute for Biotechnology and Biomedicine and Department of Biochemistry and Molecular Biology, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain.
Francesc Xavier
FX
Aviles
From the ‡Department of Medical Protein Research, VIB, B-9000 Ghent, Belgium; §Department of Biochemistry, Ghent University, B-9000 Ghent, Belgium;
Kris
K
Gevaert
From the ‡Department of Medical Protein Research, VIB, B-9000 Ghent, Belgium; §Department of Biochemistry, Ghent University, B-9000 Ghent, Belgium; petra.vandamme@vib-ugent.be julia.lorenzo@uab.es.
Petra
P
Van Damme
¶Institute for Biotechnology and Biomedicine and Department of Biochemistry and Molecular Biology, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain petra.vandamme@vib-ugent.be julia.lorenzo@uab.es.
Julia
J
Lorenzo
D002268:Carboxypeptidases / Q000235:genetics / Q000378:metabolism*; D019204:GTP-Binding Proteins; D057809:HEK293 Cells; D006801:Humans; D011499:Protein Processing, Post-Translational; D040901:Proteomics; D046929:Serine-Type D-Ala-D-Ala Carboxypeptidase; D014404:Tubulin / Q000378:metabolism
D014404:Tubulin; D002268:Carboxypeptidases; C583027:AGTPBP1 protein, human; D046929:Serine-Type D-Ala-D-Ala Carboxypeptidase; D019204:GTP-Binding Proteins