Naslov
Molecular basis for the thiol sensitivity of yeast dipeptidyl peptidase III

Autori
Jajčanin-Jozić, Nina ; Abramić, Marija

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
FEBS Journal 277 (2010), Abstracts of the 35th FEBS Congress / Perham, Richard - Oxford : Wiley-Blackwell, 2010, 283-284

Skup
35th FEBS Congress, Molecules of Life

Mjesto i datum
Göteborg, Švedska, 26.06.2010. - 01.07.2010

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
yeast dipeptidyl peptidase III; reactive cysteine residues; crystal structure

Sažetak
Dipeptidyl peptidases III (DPP III) are zinc-dependent enzymes that cleave dipeptides sequentially from the N-terminus of its substrates. In vitro metallopeptidases of this family (DPP III family, peptidase family M49) display a broad specificity towards peptides, but their in vivo substrates are mostly unknown, although physiological role in intracellular protein catabolism, pain-regulation and endogenous defense against oxidative stress is indicated. General feature of all DPPs III is inhibition by thiol reagents, implying the presence of reactive cysteine residues in, or near their active site. Since there is no absolutely conserved Cys in M49 family, and all known members are multi cysteine proteins, the identity of sulfhydryl group(s) important for activity is still speculative and could be species-specific. To address this topic, we conducted a mutational analysis of all five cysteine residues within the yeast ortholog of this family. Yeast Saccharomyces cerevisiae DPP III is a two-domain protein, highly sensitive to sulfhydryl-blocking reagents. Two cysteine residues are located in lower domain (position 113 and 130), and three in the upper domain (position 518, 626 and 639). Although there was no significant change in catalytic efficiency between the wild-type and any of Cys to Ser mutated forms, dramatic difference in sensitivity towards thiol-blocking reagents was observed. Our results showed that inactivation of wild-type yeast DPP III with 4, 4'-dithiodipyridine (DTDP) was a result of modification of two SH-groups, belonging to Cys518 and Cys639. However, only C639S protein variant showed high resistance to inactivation by para-hydroxy-mercuribenzoate (pHMB). Inspection of 1.95 Å-crystal structure of yeast DPP III revealed that Cys639 is situated in a positively charged environment which presumably enhances its ionization to thiolate anion and thereby influences its reactivity.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

POVEZANOST RADA