Giardia duodenalis 14-3-3 protein is polyglycylated by a tubulin tyrosine ligase-like member and deglycylated by two metallocarboxypeptidases.
The flagellated protozoan Giardia duodenalis is a parasite of the upper part of the small intestine of mammals, including humans, and an interesting biological model. Giardia harbors a single 14-3-3 isoform, a multifunctional protein family, that is modified at the C terminus by polyglycylation, an unusual post-translational modification consisting of the covalent addition of one or multiple glycines on the γ-carboxyl groups of specific glutamic acids. Polyglycylation affects the intracellular localization of g14-3-3, as the shortening of the polyglycine chain is correlated with a partial relocalization of 14-3-3 inside the nuclei during encystation. In this work we demonstrate that the gTTLL3, a member of the tubulin tyrosine ligase-like family, is the enzyme responsible for the 14-3-3 polyglycylation. We also identify two metallopeptidases of the M20 family, here termed gDIP1 (giardial dipeptidase 1) and gDIP2, as enzymes able to shorten the g14-3-3 polyglycine tail both in vivo and in vitro. Finally, we show that the ectopic expression of gDIP2 alters the g14-3-3 localization and strongly hampers the cyst formation. In conclusion, we have identified a polyglycylase and two deglycylases that act in concert to modulate the stage-dependent glycylation status of the multifunctional regulatory g14-3-3 protein in G. duodenalis.
Department of Infectious, Parasitic and Immunomediated Diseases, Istituto Superiore di Sanità, 00161 Rome, Italy.
Marco
M
Lalle
Serena
S
Camerini
Serena
S
Cecchetti
Claudia
C
Blasetti Fantauzzi
Marco
M
Crescenzi
Edoardo
E
Pozio
D048948:14-3-3 Proteins / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D002268:Carboxypeptidases / Q000235:genetics / Q000378:metabolism*; D005872:Giardia / Q000235:genetics / Q000378:metabolism*; D005998:Glycine / Q000235:genetics / Q000378:metabolism; D045726:Metalloproteases / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D010453:Peptide Synthases / Q000235:genetics / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D017434:Protein Structure, Tertiary; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism*
D048948:14-3-3 Proteins; D015800:Protozoan Proteins; D002268:Carboxypeptidases; D045726:Metalloproteases; D010453:Peptide Synthases; C112698:tubulin polyglutamylase; D005998:Glycine