The Aspartic Protease Ddi1 Contributes to DNA-Protein Crosslink Repair in Yeast

SUMMARYNaturally occurring or drug-induced DNA-protein crosslinks (DPCs) interfere with key DNA transactions if not timely repaired. The unique family of DPC-specific proteases Wss1/SPRTN targets DPC protein moieties for degradation, including topoisomerase-1 trapped in covalent crosslinks (Top1ccs). Here we describe that the efficient DPC disassembly requires Ddi1, another conserved predicted protease in Saccharomyces cerevisiae. We found Ddi1 in a genetic screen of the tdp1wss1 mutant defective in Top1cc processing. Ddi1 is recruited to a persistent Top1cc-like DPC lesion in an S-phase dependent manner to assist eviction of crosslinked protein from DNA. Loss of Ddi1 or its putative protease activity hypersensitize cells to DPC trapping agents independently from Wss1 and 26S proteasome, implying its broader role in DPC repair. Among potential Ddi1 targets we found the core component of RNAP II and show that its genotoxin-induced degradation is impaired in ddi1. Together, we propose that the Ddi1 protease contributes to DPC proteolysis.

Design and Evaluation of Heterobivalent PAR1–PAR2 Ligands as Antagonists of Calcium Mobilization

A novel class of bivalent ligands targeting putative Protease-Activated Receptor (PAR) heteromers has been prepared based upon reported antagonists for the subtypes PAR1 and PAR2. Modified versions of the PAR1 antagonist RWJ-58259 containing alkyne adapters were connected via cycloaddition reactions to azide-capped polyethylene glycol (PEG) spacers attached to imidazopyridazine-based PAR2 antagonists. Initial studies of the PAR1–PAR2 antagonists indicated that they inhibited G alpha q-mediated calcium mobilization in endothelial and cancer cells driven by both PAR1 and PAR2 agonists. Compounds of this novel class hold promise for the prevention of restenosis, cancer cell metastasis, and other proliferative disorders.<br>

Design and Evaluation of Heterobivalent PAR1–PAR2 Ligands as Antagonists of Calcium Mobilization

A novel class of bivalent ligands targeting putative Protease-Activated Receptor (PAR) heteromers has been prepared based upon reported antagonists for the subtypes PAR1 and PAR2. Modified versions of the PAR1 antagonist RWJ-58259 containing alkyne adapters were connected via cycloaddition reactions to azide-capped polyethylene glycol (PEG) spacers attached to imidazopyridazine-based PAR2 antagonists. Initial studies of the PAR1–PAR2 antagonists indicated that they inhibited G alpha q-mediated calcium mobilization in endothelial and cancer cells driven by both PAR1 and PAR2 agonists. Compounds of this novel class hold promise for the prevention of restenosis, cancer cell metastasis, and other proliferative disorders.<br>

Purification, characterization, and bioassay of putative protease inhibitors from Hevea brasiliensis latex

Latex, a milky white liquid, is the main product from rubber tree (Hevea brasiliensis). Latex is the cytoplasm of complex cellular networks named laticifers in which it contains many different components, including important proteins. Various types of enzymes carrying functions associated with plant defense against pathogen and wounding have been detected in latex in which one of these enzymes is protease inhibitor (PI). Plant protease inhibitor has tremendous potential as an antifungal agent which can be developed as biofungicide. In this work, protease inhibitors from B-serum (lutoid) of rubber tree latex were isolated and purified using Ion Exchange Chromatography (IEC) technique. Of the total 70 fractions of proteins extracted from the columns, only 26 fractions showed measurable levels of protein. The concentration of obtained putative protease inhibitors (three fractions of IEC) ranged from 0.007 to 0.022 mL/g B-serum. Inhibitory activity against four protease enzymes (subtilisin A, trypsin, α-chymotrypsin, and papain) showed the characteristics of Hevea putative protease inhibitors from B-serum as serine and/or cysteine protease inhibitors with more than 15% inhibitory activity of target protease. Based on SDS-PAGE visualization, the molecular weight of dominant protein considered as Hevea putative protease inhibitors was 21.5 kDa. In vitro bioassay test of antifungal activity for Hevea putative protease inhibitors showed reduced mycelium growth of Ganoderma boninense, Sclerotium sp., and Rigidosporus lignosus.

Purification, characterization, and bioassay of putative protease inhibitors from Hevea brasiliensis latex

Lateks yang menyerupai cairan susu putih diperoleh dari penyadapan kulit batang tanaman karet (Hevea brasiliensis). Lateks merupakan sitoplasma dari jaringan pembuluh bernama latisifer yang didalamnya terkandung berbagai macam komponen, termasuk protein-protein penting. Berbagai jenis enzim yang memiliki fungsi terkait pertahanan tanaman dari serangan patogen dan pelukaan telah berhasil dideteksi di dalam lateks, di antaranya protease inhibitor (PI). Protease inhibitor memiliki aktivitas senyawa antifungi sehingga berpotensi untuk dimanfaatkan sebagai biofungisida. Pada penelitian ini, protease inhibitor putatif yang berasal dari serum B (lutoid) lateks tanaman karet telah berhasil diisolasi menggunakan teknik Ion Exchange Chroma-tography. Dari total 70 fraksi protein yang diekstrak dari kolom, hanya 26 fraksi yang menunjukkan kadar protein yang terukur. Kandungan protease inhibitor putatif yang di-peroleh berkisar antara 0,0067 hingga 0,022 mL/g serum B dari hasil 3 fraksi terpilih. Aktivitas penghambatan terhadap empat enzim protease (subtilisin A, tripsin, α-kimotripsin, dan papain) menunjukkan karakteristik protease inhibitor putatif tersebut sebagai serine dan/atau cysteine inhibitor protease dengan persentase hambatan di atas 15% terhadap protease target. Hasil SDS-PAGE memperlihatkan pemisahan protein dominan yang diperkirakan merupakan protease inhibitor putatif dengan berat molekul sebesar 21,5 kDa. Uji bioassay aktivitas antifungi secara in vitro dari protease inhibitor memperlihatkan penghambatan pertumbuhan miselium dari fungi Ganoderma boninense, Sclerotium sp., dan Rigidosporus lignosus. [Kata kunci : protease inhibitor, Hevea brasiliensis, lateks, serum B, ion exchange chromatography]AbstractLatex, a milky white liquid, is the main product from rubber tree (Hevea brasiliensis). Latex is the cytoplasm of complex cellular networks named laticifers in which it contains many different components, including important proteins. Various types of enzymes carrying functions associated with plant defense against pathogen and wounding have been detected in latex in which one of these enzymes is protease inhibitor (PI). Plant protease inhibitor has tremendous potential as an antifungal agent which can be developed as biofungicide. In this work, protease inhibitors from B-serum (lutoid) of rubber tree latex were isolated and purified using Ion Exchange Chromatography (IEC) technique. Of the total 70 fractions of proteins extracted from the columns, only 26 fractions showed measurable levels of protein. The concentration of obtained putative protease inhibitors (three fractions of IEC) ranged from 0.007 to 0.022 mL/g B-serum. Inhibitory activity against four protease enzymes (subtilisin A, trypsin, α-chymotrypsin, and papain) showed the characteristics of Hevea putative protease inhibitors from B-serum as serine and/or cysteine protease inhibitors with more than 15% inhibitory activity of target protease. Based on SDS-PAGE visualization, the molecular weight of dominant protein considered as Hevea putative protease inhibitors was 21.5 kDa. In vitro bioassay test of antifungal activity for Hevea putative protease inhibitors showed reduced mycelium growth of Ganoderma boninense, Sclerotium sp., and Rigidosporus lignosus.[Keywords: protease inhibitor, Hevea brasiliensis, latex, B-serum, ion exchange chromatography]

Expression and Characterization ofCoprothermobacter proteolyticusAlkaline Serine Protease

A putative protease gene (aprE) from the thermophilic bacteriumCoprothermobacter proteolyticuswas cloned and expressed inBacillus subtilis. The enzyme was determined to be a serine protease based on inhibition by PMSF. Biochemical characterization demonstrated that the enzyme had optimal activity under alkaline conditions (pH 8–10). In addition, the enzyme had an elevated optimum temperature (60°C). The protease was also stable in the presence of many surfactants and oxidant. Thus, theC. proteolyticusprotease has potential applications in industries such as the detergent market.

An archaeal protein evolutionarily conserved in prokaryotes is a zinc-dependent metalloprotease

A putative protease gene (tldD) was previously identified from studying tolerance of letD encoding the CcdB toxin of a toxin–antidote system of the F plasmid in Escherichia coli. While this gene is evolutionarily conserved in archaea and bacteria, the proteolytic activity of encoded proteins remained to be demonstrated experimentally. Here we studied Sso0660, an archaeal TldD homologue encoded in Sulfolobus solfataricus by overexpression of the recombinant protein and characterization of the purified enzyme. We found that the enzyme is active in degrading azocasein and FITC–BSA substrates. Protease inhibitor studies showed that EDTA and o-phenanthroline, two well-known metalloprotease inhibitors, either abolished completely or strongly inhibited the enzyme activity, and flame spectrometric analysis showed that a zinc ion is a cofactor of the protease. Furthermore, the protein forms disulfide bond via the Cys416 residue, yielding protein dimer that is the active form of the enzyme. These results establish for the first time that tidD genes encode zinc-containing proteases, classifying them as a family in the metalloprotease class.

Activation of the latent PlcR regulon in Bacillus anthracis

Many genes in Bacillus cereus and Bacillus thuringiensis are under the control of the transcriptional regulator PlcR and its regulatory peptide, PapR. In Bacillus anthracis, the causative agent of anthrax, PlcR is inactivated by truncation, and consequently genes having PlcR binding sites are expressed at very low levels when compared with B. cereus. We found that activation of the PlcR regulon in B. anthracis by expression of a PlcR–PapR fusion protein does not alter sporulation in strains containing the virulence plasmid pXO1 and thereby the global regulator AtxA. Using comparative 2D gel electrophoresis, we showed that activation of the PlcR regulon in B. anthracis leads to upregulation of many proteins found in the secretome of B. cereus, including phospholipases and proteases, such as the putative protease BA1995. Transcriptional analysis demonstrated expression of BA1995 to be dependent on PlcR–PapR, even though the putative PlcR recognition site of the BA1995 gene does not exactly match the PlcR consensus sequence, explaining why this protein had escaped recognition as belonging to the PlcR regulon. Additionally, while transcription of major PlcR-dependent haemolysins, sphingomyelinase and anthrolysin O is enhanced in response to PlcR activation in B. anthracis, only anthrolysin O contributes significantly to lysis of human erythrocytes. In contrast, the toxicity of bacterial culture supernatants from a PlcR-positive strain towards murine macrophages occurred independently of anthrolysin O expression in vitro and in vivo.