Isolation and characterization of a novel adenosine deaminase inhibitor, IADA-7, from Bacillus sp. J-89.

Adenosine deaminase (ADA), an enzyme involved in purine metabolism, catalyzes the hydrolytic breakdown of adenosine into inosine and free ammonia. ADA regulation has been targeted as a potential therapeutic agent for viral infections and lymphoproliferative disorders. In this study, we isolated a novel ADA inhibitor from a culture of Bacillus sp. J-89, and evaluated its anti-proliferative activity on human cancer cell lines. The ADA inhibitor was deduced as a 2-N-methyl-2,4-diazacycloheptanone by analyses of UV, IR, EI-MASS, (1)H-NMR, (13)C-(1)H NMR, and (13)C-NMR spectroscopy, and was designated IADA-7. IADA-7 was shown to inhibit purified mammalian and Actinomyces ADA. IADA-7 also inhibited the proliferation of both Jurkat T cells (IC(50) = 15 microg/mL) and J 82 (human transitional-cell carcinoma, bladder) cells (IC(50) = 25 microg/mL). In Jurkat T cells, apoptosis with 15 microg/mL IADA-7 for 24 and 48 hours was 9 and 13%, respectively. These results suggest that IADA-7 can inhibit ADA activity in multiple species and that it may represent a good candidate as an anti-cancer therapeutic agent due to its demonstrated anti-proliferative activity on cancer cells.

Characterization of a gene encoding cellulase from uncultured soil bacteria.

To detect cellulases encoded by uncultured microorganisms, we constructed metagenomic libraries from Korean soil DNAs. Screenings of the libraries revealed a clone pCM2 that uses carboxymethyl cellulose (CMC) as a sole carbon source. Further analysis of the insert showed two consecutive ORFs (celM2 and xynM2) encoding proteins of 226 and 662 amino acids, respectively. A multiple sequence analysis with the deduced amino acid sequences of celM2 showed 36% sequence identity with cellulase from the Synechococcus sp., while xynM2 had 59% identity to endo-1,4-beta-xylanase A from Cellulomonas pachnodae. The highest enzymatic CMC hydrolysis was observable at pH 4.0 and 45 degrees C with recombinant CelM2 protein. Although the enzyme CelM2 additionally hydrolyzed avicel and xylan, no substrate hydrolysis was observed on oligosaccharides such as cellobiose, pNP-beta-cellobioside, pNP-beta-glucoside, and pNP-beta-xyloside. These results showed that CelM2 is a novel endo-type cellulase.

Hepatitis C virus core protein represses the p21 promoter through inhibition of a TGF-beta pathway.

The increased proliferation rate of hepatocytes is one of the major risk factors for the development of hepatocellular carcinoma. In this study, we investigated the mechanism by which hepatitis C virus (HCV) core protein represses transcription of the universal cyclin-dependent kinase inhibitor p21 gene in murine fibroblast NIH 3T3 cells. From the transient reporter assays of p21 promoter, we found that the TGF-beta-responsive element (TbetaRE) located between -83 and -74 of the p21 promoter is responsible for the effect. The TGF-beta-induced p21 promoter activity was specifically decreased by HCV core protein and in the presence of the inhibitory Smad7 the repression effect was almost completely abolished. Furthermore, HCV core protein stimulated the growth rate of NIH 3T3 cells and could overcome growth arrest by TGF-beta but not by butyrate, suggesting that HCV core protein stimulates cell cycle progression by repressing p21 transcription through a TGF-beta pathway.