Naslov
Reactive cysteine in the active-site motif of Bacteroides thetaiotaomicron dipeptidyl peptidase III is a regulatory residue for the enzyme activity

Autori
Vukelić, Bojana ; Salopek-Sondi, Branka ; Špoljarić, Jasminka ; Sabljić, Igor ; Meštrović, Nevenka ; Agić, Dejan ; Abramić, Marija

Izvornik
Biological chemistry (1431-6730) 393 (2012), 1/2; 37-46

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
anaerobic bacteria ; enzyme mutation ; metallopeptidase M49 ; sulfhydryl reagent

Sažetak
Dipeptidyl peptidase III (DPP III), a member of the metallopeptidase family M49, was considered as an exclusively eukaryotic enzyme involved in intracellular peptide catabolism and pain modulation. New data on genome sequences revealed only in 2003 the first prokaryotic orthologs, which showed low sequence similarity to eukaryotic ones and a cysteine residue in the zinc-binding motif HEXXGH. Here we report the cloning and heterologous expression of DPP III from the human gut symbiont Bacteroides thetaiotaomicron. The catalytic efficiency of bacterial DPP III for preferred synthetic substrate hydrolysis was very similar to that of the human host enzyme. Substitution of Cys450 from the active-site motif by serine did not change the enzymatic activity substantially. However, this residue was wholly responsible for the inactivation effect of sulfhydryl reagents. Molecular modelling indicated seven basic amino acid residues in the local environment of Cys450 as a possible cause for its high reactivity. Sequence analysis of 81 bacterial M49 peptidases showed conservation of the HECLGH motif in 73 primary structures. The majority of proteins lacking an active-site Cys originated from aerobic bacteria. Data obtained suggest that Cys450 of B. thetaiotaomicron DPP III is a regulatory residue for the enzyme activity.

Izvorni jezik
Engleski

Znanstvena područja
Kemija, Biologija

POVEZANOST RADA