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The known metabolite, enniatin B, and a cyclic tetrapeptide, JM47, which is a new natural product, were extracted from brown rice cultures of a marine fungus, identified as a Fusarium species, isolated from the marine alga Codium fragile. NMR studies, including 15N HMQC and 15N HMBC, established the structure of JM47 as cyclo(Ala-Ala-Aoh-Pro), where Aoh is the amino acid, (2S,9S)-2-amino-8-oxo-9-hydroxydecanoic acid. The absolute stereochemistry of the Aoh side chain carbinol centre was determined using Mosher ester methodology. Analysis of NOESY data assisted by molecular modelling revealed an alternating L-, D-, L-, D-configuration for the tetrapeptide core. The absolute stereochemistry of the core was determined by acidic hydrolysis and chiral TLC analysis of the proline residue. JM47 belongs to the HC-toxin family of cyclic tetrapeptides which possess a 2-amino-8-oxo-9,10-epoxydecanoic acid residue in place of the Aoh unit. This is the first report of an analogue of HC-toxin from a marine Fusarium species. 相似文献
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Uchimiya Hirofumi Fujii Seiichi Huang Jirong Fushimi Takaomi Nishioka Masanori Kim Kyung-Min Yamada Maki Kawai Kurusu Takamitsu Kuchitsu Kazuyuki Tagawa Michito 《Molecular breeding : new strategies in plant improvement》2002,9(1):25-31
We isolated a rice gene (denoted YK1), which showed78 percent amino acid sequence homology to the maize HM1gene. A chimeric gene consisting of a promoter and first intron of maizeubiquitin gene and the cDNA of YK1 was introduced intorice via Agrobacterium mediated transformation. Transgenic riceplants overexpressing this chimeric gene were resistant to rice blast(Magnaporthe grisea) disease, which is one of the mostserious pathogens in rice. Furthermore, the same transgenic plants conferredhigh tolerance to several abiotic stresses such as NaCl, UV-C, submergence, andhydrogen peroxide. 相似文献
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HC-toxin is an epoxide-containing cyclic tetrapeptide that is a critical virulence determinant in the pathogenic interaction
between the filamentous fungus Cochliobolus carbonum and maize. HC-toxin exerts a potent cytostatic effect on plant and animal cells by inhibiting histone deacetylase. The biosynthesis
of HC-toxin by C. carbonum is controlled by a complex genetic locus, TOX2, that contains multiple, duplicated copies of genes encoding export and biosynthetic enzymes. A new gene in the TOX2 complex, TOXE, has now been isolated. Mutation of TOXE by targeted gene disruption has no effect on growth and sporulation but abolishes HC-toxin production and pathogenicity.
TOXE is required for the expression of three genes with a known or putative role in HC-toxin production, but is not required for
expression of HTS1, which encodes the large, multifunctional peptide synthetase that is the central enzyme in HC-toxin biosynthesis. At its
N-terminus, TOXEp has a bZIP basic DNA binding domain, but it does not contain any discernible leucine zipper or helix-loop-helix.
At its carboxy terminus, TOXEp contains four ankyrin repeats. In having these two common regulatory motifs in a single polypeptide,
TOXEp appears to represent a novel class of regulatory protein. TOXE is present only in HC-toxin-producing (Tox2+) isolates of C. carbonum. Most Tox2+ isolates have two copies; in strain SB111, one copy of TOXE is on the same 3.5-Mb chromosome that contains all of the other genes known to be involved in HC-toxin biosynthesis, and
the second copy of TOXE is on a 0.7-Mb chromosome.
Received: 20 April 1998 / Accepted: 21 September 1998 相似文献
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