Dataset Information

Positional proteomics identification of the natural substrates of cytosolic carboxypeptidases

ABSTRACT: Cytosolic carboxypeptidases (CCPs) constitute a new subfamily of M14 metallocarboxypeptidases associated to axonal regeneration and neuronal degeneration, amongst 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 due to 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 7 new putative CCP1 protein substrates, including ribosomal proteins, translation factors and high mobility group proteins.

INSTRUMENT(S): LTQ Orbitrap Velos

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Hek-293ft Cell

SUBMITTER: Sebastian Tanco

LAB HEAD: Kris Gevaert

PROVIDER: PXD000834 | Pride | 2014-12-02

REPOSITORIES: Pride

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Publications

C-terminomics screen for natural substrates of cytosolic carboxypeptidase 1 reveals processing of acidic protein C termini.

Tanco Sebastian S Tort Olivia O Demol Hans H Aviles Francesc Xavier FX Gevaert Kris K Van Damme Petra P Lorenzo Julia J

Molecular & cellular proteomics : MCP 20141107 1

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 an ...[more]

PMID: 25381060

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Project description:Co-translational N-terminal (Nt-) acetylation of nascent polypeptides is catalyzed by N-terminal acetyltransferases (NATs). The very N-terminal amino acid sequence is the major factor determining whether or not a given protein is Nt-acetylated. In humans, six different NATs, denoted NatA-NatF, are identified. In the current study we used N-terminal COFRADIC analysis to define the in vivo substrate specificity of Naa50 (Nat5)/NatE as this has long remained elusive. Three yeast strains were generated; a control strain endogenously expressing yNaa50, a deletion strain depleted of yNaa50 and a strain deleted of yNaa50 but ectopically expressing human Naa50. When comparing the Nt-acetylation status of different N-termini in the control strain with the deletion strain, a reduction in Nt-acetylation for several yeast proteins was observed. To our surprise, these substrates were not of the predicted NatE-type substrates, but rather canonical NatA substrates. Further, ectopic expression of hNaa50 mainly resulted in the Nt-acetylation of a selected class of otherwise Nt-free yeast N-termini besides increasing the degree of Nt-acetylation of several other yeast proteins, and as such (partially) complementing those N-termini displaying reduced Nt-acetylation upon yNAA50-deletion. The preferred substrates of hNaa50 were predominantly Met-starting N-termini including Met-Lys-, Met-Val-, Met-Ala-, Met-Tyr-, Met-Phe-, Met-Leu-, Met-Ser- and Met-Thr, and highly overlapped with the previously identified human Naa60/NatF substrate specificity profile. Identification of several hNaa50 substrates with a small amino acid in the second position also revealed a potential interplay between the NATs and methionine aminopeptidases (MetAPs). The initiator Methionine (iMet) is normally cleaved off by MetAPs when the second amino acid is small, but our in vitro data suggest that in contrast to a free iMet, an Nt-acetylated iMet is not hydrolyzed by MetAPs. Thus, Naa50-mediated Nt-acetylation may potentially act as a mechanism to retain the iMet of proteins with a small amino acid at the second position that normally would be hydrolyzed.

Dataset Information

Positional proteomics identification of the natural substrates of cytosolic carboxypeptidases

Publications

C-terminomics screen for natural substrates of cytosolic carboxypeptidase 1 reveals processing of acidic protein C termini.

Similar Datasets

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