Cloning and recombinant expression of Caspase-activated DNase
orthologous gene of Giardia lamblia
Abstract
In eukaryotic cells, mitochondria play a key role in apoptosis, but
Giardia lamblia only possesses a mitochondrial remnant, the
mitosome. However, this protozoan can die by an apoptosis-like process,
probably by an apoptosis-mitochondrial-independent pathway. Here, we
aimed to identify, clone, express, and characterize the
caspase-activated DNase (CAD) of G. lamblia. Using a commercial
polyclonal antibody that recognizes mouse, rat, and human CAD (hCAD), we
developed an immunoproteomic analysis using a crude extract of
curcumin-treated G. lamblia trophozoites (CEGl), detected a spot
of 42kDa, and pI 9.4, similar to hCAD. This spot was sequenced by LC-MS.
The proteomic profile (eleven peptides) matched with a novel protein of
383 residues, with a predicted 42KDa, pI 9.4, with a CIDE-N domain and
putative H-K-H cata-lytic motif. Afterward, we cloned the full-length
gene (GenBank: ON707040), expressed it, and purified it as a H
6tag-recombinant protein in Escherichia coli,
which also was recognized by commercial anti-CAD. In conclusion, gCAD is
an orthologous protein of hCAD and will allow us to determine its role
in the apoptosis-like signaling pathway in G. lamblia.