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Krock B.,Alfred Wegener Institute for Polar and Marine Research | Tillmann U.,Alfred Wegener Institute for Polar and Marine Research | Witt M.,BrukerDaltonik GmbH | Gu H.,Third Institute of Oceanography
Harmful Algae | Year: 2014

Azadinium poporum is a small dinoflagellate from the family Amphidomataceae which is known for the potential production of azaspiracids (AZAs) causative of azaspiracid shellfish poisoning (AZP). A. poporum has been recorded from European and western Pacific waters. Here we report on the high variability of toxin profiles within this species in Chinese coastal waters. Out of 16 analyzed strains of A. poporum from different geographic locations along the Chinese coastline, three strains proved not to contain AZAs, whereas 13 strains contained different combinations of AZA-2, AZA-11, AZA-36, a yet unknown isomer of AZA-1 (named AZA-40) and new AZA with yet unreported molecular mass of 853Da (named AZA-41). The new AZA-40, other than AZA-1 itself, belongs to the recently discovered "348-type" group, which in tandem mass spectrometry displays a group 4 fragment with m/z 348 instead of the group 4 fragment of the classic AZAs with m/z 362, indicating a shift of a methyl group from the C24-C40 part of the molecule (rings F-I) to the C2-C9 part (carboxylic side chain and ring A). AZA-41 apparently is a dehydro variant of AZA-2. In addition, a previously reported AZA with a molecular mass 871DA could be unambiguously assigned to AZA-11, which is known to be a shellfish metabolite of AZA-2. This is the first report of AZA-11 being also de novo synthetized by dinoflagellates. © 2014 Elsevier B.V.

Zhu F.,Zhejiang Agriculture And forestry University | Jin M.,Third Institute of Oceanography
Fish and Shellfish Immunology | Year: 2015

White spot syndrome virus (WSSV) is a shrimp pathogen responsible for significant economic loss in commercial shrimp farms and until now, there has been no effective approach to control this disease. In this study, tryptophol (indole-3-ethanol) was identified as a metabolite involved in bacteriophage-thermophile interactions. The dietary addition of tryptophol reduced the mortality in shrimp Marsupenaeus japonicus when orally challenged with WSSV. Our results revealed that 50 mg/kg tryptophol has a better protective effect in shrimp than 10 or 100 mg/kg tryptophol. WSSV copies in shrimp were reduced significantly (P < 0.01) when supplemented with 50 mg/kg tryptophol, indicating that virus replication was inhibited by tryptophol. Consequently, tryptophol represents an effective antiviral dietary supplement for shrimp, and thus holds significant promise as a novel and efficient therapeutic approach to control WSSV in shrimp aquaculture. © 2015 Elsevier Ltd.

Jin M.,Zhejiang University | Jin M.,Third Institute of Oceanography | Xu C.,Zhejiang University | Zhang X.,Zhejiang University
Applied Microbiology and Biotechnology | Year: 2015

Small metabolites can participate in the virus-host interactions in eukaryotes. However, little is known about roles of metabolites in the interactions between bacteria and bacteriophages. In this study, the metabolomic profilings of bacteriophage GVE2-infected and virus-free Geobacillus sp. E263, a thermophilic bacterium isolated from a deep-sea hydrothermal vent, were characterized. The results showed that metabolites tryptophol, adenine, and hydroxybenzylalcohol were significantly elevated in Geobacillus sp. E263 in response to the GVE2 infection. Furthermore, our data indicated that tryptophol was involved in the bacteriophage infection. Tryptophol could inhibit the infection/replication of GVE2 by interacting with the host’s Clp protease. Therefore, our study revealed novel aspects of metabolites during the bacteriophage infection in high-temperature environment. © 2015, Springer-Verlag Berlin Heidelberg.

Ross A.C.,University of California at San Diego | Xu Y.,Hong Kong University of Science and Technology | Lu L.,Hong Kong University of Science and Technology | Kersten R.D.,University of California at San Diego | And 5 more authors.
Journal of the American Chemical Society | Year: 2013

Thalassospiramides A and B are immunosuppressant cyclic lipopeptides first reported from the marine α-proteobacterium Thalassospira sp. CNJ-328. We describe here the discovery and characterization of an extended family of 14 new analogues from four Tistrella and Thalassospira isolates. These potent calpain 1 protease inhibitors belong to six structure classes in which the length and composition of the acylpeptide side chain varies extensively. Genomic sequence analysis of the thalassospiramide-producing microbes revealed related, genus-specific biosynthetic loci encoding hybrid nonribosomal peptide synthetase/polyketide synthases consistent with thalassospiramide assembly. The bioinformatics analysis of the gene clusters suggests that structural diversity, which ranges from the 803.4 Da thalassospiramide C to the 1291.7 Da thalassospiramide F, results from a complex sequence of reactions involving amino acid substrate channeling and enzymatic multimodule skipping and iteration. Preliminary biochemical analysis of the N-terminal nonribosomal peptide synthetase module from the Thalassospira TtcA megasynthase supports a biosynthetic model in which in cis amino acid activation competes with in trans activation to increase the range of amino acid substrates incorporated at the N terminus. © 2012 American Chemical Society.

Zhang Y.,Third Institute of Oceanography | Zhao J.,Xiamen University | Zeng R.,Third Institute of Oceanography
Extremophiles | Year: 2011

A metagenomic cosmid library was constructed, in which the insert DNA was derived from the coastal sediment near Antarctic China Zhongshan Station. One clone (ACPRO001) expressing protease activity was isolated from the library using milk agar plates. Sequencing of the clone revealed a novel protease gene. The amino acid sequence comparison and phylogenetic analysis indicated that it could be classified as a subtilisin-like serine protease, though the highly conserved residue Asp was replaced by Ala. The ACPRO001 protease gene was expressed in pET-His and purified for characterization. The optimal temperature and pH for the activity of the ACPRO001 protease were 60°C and pH 9. 0, respectively. The enzyme retained about 73% of residual activity after 2 h incubation at 50°C in the presence of Ca 2+. The presence of Ca 2+ increased the thermostability of ACPRO001 protease obviously. The enzymatic activity was inhibited by 1 mM phenylmethyl sulfonylfluoride (PMSF) and hydrochloride 4-(2-aminoethyl)-benzenesulfonyl fluoride (AEBSF), indicating that it was a serine protease. © 2010 Springer.

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