Sesquiterpenoids with PTP1B Inhibitory Activity and Cytotoxicity from the Edible Mushroom Pleurotus citrinopileatus.

One new perhydrobenzannulated 5,5-spiroketal sesquiterpene, pleurospiroketal F (1), as well as six new modified bisabolene sesquiterpenes pleurotins A-F (2-7) were isolated from solid-state fermentation of Pleurotus citrinopileatus. The structures of compounds 1-7 were determined by NMR and MS spectroscopic analysis. The absolute configuration of 1 was determined by X-ray diffraction analysis, while the absolute configurations of 3-7 were assigned using the in situ dimolybdenum circular dichroism method and circular dichroism data comparison. Protein tyrosine phosphatase 1B plays a crucial role as a negative regulator of the insulin-dependent signal cascades. Therefore, the protein tyrosine phosphatase 1B inhibitor can be used for treating type 2 diabetes mellitus and obesity. Compounds 2 and 6 showed moderate inhibitory effects on protein tyrosine phosphatase 1B with IC50 s of 32.1 µM and 30.5 µM, respectively. The kinetic study confirmed compound 2 to be a noncompetitive inhibitor. Compounds 1-7 did not show cytotoxic activity against cancer cell lines (IC50 > 50 µM).

Tricycloalternarenes F-H: three new mixed terpenoids produced by an endolichenic fungus Ulocladium sp. using OSMAC method.

Three new mixed terpenoids, tricycloalternarenes (TCAs) F-H (1-3), together with ten known tricycloalternarenes (4-13), were isolated from the Czapek's culture of an endophytic fungus Ulocladium sp. Their structures were identified by extensive spectroscopic experiments (NMR and MS) and comparison with literature data. TCA 1b (5) showed weak activity against the Bacille Calmette-Guerin strain with the MIC of 125µg/mL. TCA 9b (10) exhibited strong cytotoxic activity against Hela cell line with IC50 of 8.58µM.

AidC, a novel N-acylhomoserine lactonase from the potato root-associated cytophaga-flavobacteria-bacteroides (CFB) group bacterium Chryseobacterium sp. strain StRB126.

N-acylhomoserine lactones (AHLs) are used as quorum-sensing (QS) signal molecules by many gram-negative bacteria. We have reported that Chryseobacterium sp. strain StRB126, which was isolated from the root surface of potato, has AHL-degrading activity. In this study, we cloned and characterized the aidC gene from the genomic library of StRB126. AidC has AHL-degrading activity and shows homology to several metallo-ß-lactamase proteins from Bacteroidetes, although not to any known AHL-degrading enzymes. Purified AidC, as a maltose-binding fusion protein, showed high degrading activity against all tested AHLs, whether short- or long-chain forms, with or without substitution at carbon 3. High-performance liquid chromatography (HPLC) analysis revealed that AidC functions as an AHL lactonase catalyzing AHL ring opening by hydrolyzing lactones. An assay to determine the effects of covalent and ionic bonding showed that Zn(2+) is important to AidC activity both in vitro and in vivo. In addition, the aidC gene could also be PCR amplified from several other Chryseobacterium strains. In conclusion, this study indicated that the aidC gene, encoding a novel AHL lactonase, may be widespread throughout the genus Chryseobacterium. Our results extend the diversity and known bacterial hosts of AHL-degrading enzymes.

Diversity and distribution of N-acylhomoserine lactone (AHL)-degrading activity and AHL-lactonase (AiiM) in genus microbacterium.

N-Acylhomoserine lactone (AHL)-degrading enzyme, AiiM, was identified from the potato leaf-associated Microbacterium testaceum StLB037. In this study, we cloned eight aiiM gene homologues from other AHL-degrading Microbacterium strains. The similarity of the chromosomal locus of the aiiM gene is associated with the phylogenetic classification based on 16S rRNA. Degenerate PCR revealed that the aiiM gene was only conserved in AHL-degrading Microbacterium strains, but not in fifteen Microbacterium type strains or two Microbacterium isolates from other plants. These results suggested that the high level of AHL-degrading activity in Microbacterium strains was caused by the aiiM gene encoded on their chromosome.

Genome sequence of Microbacterium testaceum StLB037, an N-acylhomoserine lactone-degrading bacterium isolated from potato leaves.

Microbacterium testaceum is an endophytic Gram-positive bacterium that resides within plant hosts. M. testaceum StLB037 was isolated from potato leaves and shows N-acylhomoserine lactone-degrading activity. Here, we present the 3.98-Mb complete genome sequence of StLB037, with an average GC content of 70.28%.

AiiM, a novel class of N-acylhomoserine lactonase from the leaf-associated bacterium Microbacterium testaceum.

N-Acylhomoserine lactones (AHLs) are used as quorum-sensing signal molecules by many Gram-negative bacteria. We have reported that Microbacterium testaceum StLB037, which was isolated from the leaf surface of potato, has AHL-degrading activity. In this study, we cloned the aiiM gene from the genomic library of StLB037, which has AHL-degrading activity and shows high homology with the alpha/beta hydrolase fold family from Actinobacteria. Purified AiiM as a maltose binding fusion protein showed high degrading activity of AHLs with both short- and long-chain AHLs with or without substitution at carbon 3. High-performance liquid chromatography analysis revealed that AiiM works as an AHL lactonase that catalyzes AHL ring opening by hydrolyzing lactones. In addition, expression of AiiM in the plant pathogen Pectobacterium carotovorum subsp. carotovorum reduced pectinase activity markedly and attenuated soft rot symptoms on potato slices. In conclusion, this study indicated that AiiM might be effective in quenching quorum sensing of P. carotovorum subsp. carotovorum.