Naslov
Novel structural studies of prokaryotic dipeptidyl peptidase III

Autori
Sabljić, Igor ; Gruber, Karl ; Macheroux, Peter ; Abramić, Marija ; Luić, Marija

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, neobjavljeni rad, znanstveni

Skup
Integrative structural biology

Mjesto i datum
Erice, Italija, 02.06.2017. - 11.06.2017

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
Dipeptidil-peptidaza III ; X-ray difrakcija ; Strukturna biologija
(Dipeptidyl peptidase III ; X-ray diffraction ; Structural biology)

Sažetak
Dipeptidyl peptidase III (DPP III) is widely distributed cytosolic zinc-peptidase from the M49 family that hydrolyses dipeptides from the N-termini of peptide substrates. During the last few decades, in the research focus were eukaryotic DPPs III involved in intracellular peptide catabolism, oxidative stress response and, as postulated recently, in pain modulation. Crystal structures of yeast and human DPPs III have been solved. Additionally, few human DPP III structures in complex with different peptides are available in the protein data bank (PDB). On the other hand, the knowledge about prokaryotic DPP III is very scarce and no bacterial 3D-structures are published. We have been studying two bacterial orthologs of the M49 family: DPP III from the human gut symbiont Bacteroides thetaiotaomicron (Bt) and from the Caldithrix abyssi, thermophile which inhabits hydrothermal vents. After some efforts, both enzymes were crystallized and anomalous diffraction data from the zinc atom collected at synchrotron. Due to the low sequence identity with eukaryotic DPPs III, molecular replacement method was unsuccessful, and trials to solve the crystal structures using anomalous scattering of zinc atom gave no results due to the weak signal. Finally, both proteins were labelled using selenomethionine and their structures solved using single wavelength anomalous dispersion of selenium atoms. Besides the structure of the wild-type BtDPP III, complex of this enzyme with the inhibitor, Tyr-Phe-NHOH, has also been solved. Like in the human DPP III, in the prokaryotic protein we have observed a large domain movement upon inhibitor binding, confirming the domain dynamics as a prerequisite for catalysis in metallopeptidase family M49. Interestingly, bacterial DPP III lacks the 30 amino acids long loop in the upper structural domain that in the human DPP III contains the ETGE motif supposed to be responsible for binding KEAP1, a repressor protein from the Keap1-Nrf2 signalling pathway.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

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