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Conservation of the extended substrate specificity profiles among homologous granzymes across species.

ABSTRACT: Granzymes are structurally related serine proteases involved in cell death and immunity. To date four out of five human granzymes have assigned orthologs in mice; however for granzyme H, no murine ortholog has been suggested and its role in cytotoxicity remains controversial. Here, we demonstrate that, as is the case for granzyme C, human granzyme H is an inefficient cytotoxin that together with their similar pattern of GrB divergence and functional similarity strongly hint to their orthologous relationship. Besides analyzing the substrate specificity profile of granzyme H by substrate phage display, substrate cleavage susceptibility of human granzyme H and mouse granzyme C was assessed on a proteome-wide level. The extended specificity profiles of granzymes C and H (i.e. beyond cleavage positions P4-P4') match those previously observed for granzyme B. We demonstrate conservation of these extended specificity profiles among various granzymes as granzyme B cleavage susceptibility of an otherwise granzyme H/C specific cleavage site can simply be conferred by altering the P1-residue to aspartate, the preferred P1-residue of granzyme B. Our results thus indicate a conserved, but hitherto underappreciated specificity-determining role of extended protease-substrate contacts in steering cleavage susceptibility.

SUBMITTER: Plasman K

PROVIDER: S-EPMC3790301 | biostudies-literature | 2013 Oct

REPOSITORIES: biostudies-literature

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Conservation of the extended substrate specificity profiles among homologous granzymes across species.

Plasman Kim K Maurer-Stroh Sebastian S Ahmad Jamshaid J Hao Han H Kaiserman Dion D Sirota Fernanda L FL Jonckheere Veronique V Bird Phillip I PI Gevaert Kris K Van Damme Petra P

Molecular & cellular proteomics : MCP 20130620 10

Granzymes are structurally related serine proteases involved in cell death and immunity. To date four out of five human granzymes have assigned orthologs in mice; however for granzyme H, no murine ortholog has been suggested and its role in cytotoxicity remains controversial. Here, we demonstrate that, as is the case for granzyme C, human granzyme H is an inefficient cytotoxin that together with their similar pattern of GrB divergence and functional similarity strongly hint to their orthologous ...[more]

PMID: 23788529

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Project description:Granzymes are a family of structurally related serine proteases involved in immunity. To date four out of five human granzymes have been assigned orthologues in mice; however for granzyme H, no clear murine orthologue has been suggested and its role in cytotoxicity remains controversial. In this study, we demonstrate that granzyme H is an inefficient cytotoxin. Besides analyzing the substrate specificity profile of granzyme H by means of substrate phage display, we assessed human granzyme H and mouse granzyme C cleavage susceptibility on a proteome-wide level. The extended specificity profiles of granzyme C and granzyme H (i.e. beyond P4-P4') match those previously observed for granzyme B. We demonstrate conservation of these extended specificity profiles among various granzymes since granzyme B cleavage susceptibility of an otherwise granzyme H/C specific cleavage site can be conferred simply by altering the P1-residue to aspartate, the preferred P1-residue of granzyme B. Our results thus indicate a conserved, but hitherto generally underappreciated specificity-determining role of extended protease-substrate contacts in steering cleavage susceptibility. Bio-IT: The spectra were searched with Mascot Daemon 2.2. The following search parameters were used. Peptide mass tolerance was set at 0.2 Da and peptide fragment mass tolerance at 0.1 Da; with the ESI-QUAD-TOF as selected instrument for peptide fragmentation rules for the Q-TOF Premier data. Endoproteinase semiArg-C/P (i.e., no restriction towards arginine-proline cleavage) was set as enzyme allowing one missed cleavage. Variable modifications were pyroglutamate formation of N-terminal glutamine, pyrocarbamidomethyl formation of N-terminal alkylated cysteine, deamidation of asparagine, acetylation or tri-deuteroacetylation of the alpha-N-terminus. Fixed modifications were methionine oxidation (sulfoxide), carbamidomethyl for cysteine, tri-deuteroacetylation of lysine and for identifying heavy labelled peptides, [13C6] or [13C615N4]-arginine were additionally set as fixed modifications. The spectra and identifications were stored in ms_lims

Project description:BACKGROUND: Previous screening of the substrate repertoires and substrate specificity profiles of granzymes resulted in long substrate lists highly likely containing bystander substrates. Here, a recently developed degradomics technology that allows distinguishing efficiently from less efficiently cleaved substrates was applied to study the degradome of mouse granzyme B (mGrB). RESULTS: In vitro kinetic degradome analysis resulted in the identification of 37 mGrB cleavage events, 9 of which could be assigned as efficiently targeted ones. Previously, cleavage at the IEAD75 tetrapeptide motif of Bid was shown to be efficiently and exclusively targeted by human granzyme B (hGrB) and thus not by mGrB. Strikingly, and despite holding an identical P4-P1 human Bid (hBid) cleavage motif, mGrB was shown to efficiently cleave the BCL2/adenovirus E1B 19 kDa protein-interacting protein 2 or BNIP-2 at IEAD28. Like Bid, BNIP-2 represents a pro-apoptotic Bcl-2 protein family member and a potential regulator of GrB induced cell death. Next, in vitro analyses demonstrated the increased efficiency of human and mouse BNIP-2 cleavage by mGrB as compared to hGrB indicative for differing Bid/BNIP-2 substrate traits beyond the P4-P1 IEAD cleavage motif influencing cleavage efficiency. Murinisation of differential primed site residues in hBNIP-2 revealed that, although all contributing, a single mutation at the P3' position was found to significantly increase the mGrB/hGrB cleavage ratio, whereas mutating the P1' position from I29?>?T yielded a 4-fold increase in mGrB cleavage efficiency. Finally, mutagenesis analyses revealed the composite BNIP-2 precursor patterns to be the result of alternative translation initiation at near-cognate start sites within the 5' leader sequence (5'UTR) of BNIP-2. CONCLUSIONS: Despite their high sequence similarity, and previously explained by their distinct tetrapeptide specificities observed, the substrate repertoires of mouse and human granzymes B only partially overlap. Here, we show that the substrate sequence context beyond the P4-P1 positions can influence orthologous granzyme B cleavage efficiencies to an unmatched extent. More specifically, in BNIP-2, the identical and hGrB optimal IEAD tetrapeptide substrate motif is targeted highly efficiently by mGrB, while this tetrapeptide motif is refractory towards mGrB cleavage in Bid.

Project description:During fruit ripening, strawberries show distinct changes in the flavonoid classes that accumulate, switching from the formation of flavan 3-ols and flavonols in unripe fruits to the accumulation of anthocyanins in the ripe fruits. In the common garden strawberry (Fragaria×ananassa) this is accompanied by a distinct switch in the pattern of hydroxylation demonstrated by the almost exclusive accumulation of pelargonidin based pigments. In Fragaria vesca the proportion of anthocyanins showing one (pelargonidin) and two (cyanidin) hydroxyl groups within the B-ring is almost equal. We isolated two dihydroflavonol 4-reductase (DFR) cDNA clones from strawberry fruits, which show 82% sequence similarity. The encoded enzymes revealed a high variability in substrate specificity. One enzyme variant did not accept DHK (with one hydroxyl group present in the B-ring), whereas the other strongly preferred DHK as a substrate. This appears to be an uncharacterized DFR variant with novel substrate specificity. Both DFRs were expressed in the receptacle and the achenes of both Fragaria species and the DFR2 expression profile showed a pronounced dependence on fruit development, whereas DFR1 expression remained relatively stable. There were, however, significant differences in their relative rates of expression. The DFR1/DFR2 expression ratio was much higher in the Fragaria×ananassa and enzyme preparations from F.×ananassa receptacles showed higher capability to convert DHK than preparations from F. vesca. Anthocyanin concentrations in the F.×ananassa cultivar were more than twofold higher and the cyanidin:pelargonidin ratio was only 0.05 compared to 0.51 in the F. vesca cultivar. The differences in the fruit colour of the two Fragaria species can be explained by the higher expression of DFR1 in F.×ananassa as compared to F. vesca, a higher enzyme efficiency (Kcat/Km values) of DFR1 combined with the loss of F3'H activity late in fruit development of F.×ananassa.

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Conservation of the extended substrate specificity profiles among homologous granzymes across species.

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Conservation of the extended substrate specificity profiles among homologous granzymes across species.

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