A reaction sequence, norsolorinic acid (NA)-->averantin (AVN)-->5'-hydroxyaverantin (HAVN)-->averufin (AVR), is the early part of a biosynthetic pathway for aflatoxins. In this study, we determined the stereochemicalrelationship among these metabolites by using chiral high-performance liquid chromatography. In cell-free experiments using the cytosol fraction of Aspergillus parasiticus NIAH-26, (1'S)-AVN
<i>adhA</i>
in
<i>Aspergillus parasiticus</i>
Is Involved in Conversion of 5′-Hydroxyaverantin to Averufin
作者:Perng-Kuang Chang、Jiujiang Yu、Kenneth C. Ehrlich、Stephen M. Boue、Beverly G. Montalbano、Deepak Bhatnagar、Thomas E. Cleveland
DOI:10.1128/aem.66.11.4715-4719.2000
日期:2000.11
cluster of Aspergillusparasiticus SU-1. The deduced ADHA amino acid sequence contained two conserved motifs found in short-chain alcohol dehydrogenases-a glycine-rich loop (GXXXGXG) that is necessary for interaction with NAD(+)-NADP(+), and the motif YXXXK, which is found at the active site. A. parasiticus SU-1, which produces aflatoxins, has two copies of adhA (adhA1), whereas A. parasiticus SRRC 2043
Involvement of Two Cytosolic Enzymes and a Novel Intermediate, 5′-Oxoaverantin, in the Pathway from 5′-Hydroxyaverantin to Averufin in Aflatoxin Biosynthesis
作者:Emi Sakuno、Kimiko Yabe、Hiromitsu Nakajima
DOI:10.1128/aem.69.11.6418-6426.2003
日期:2003.11
During aflatoxin biosynthesis, 5'-hydroxyaverantin (HAVN) is converted to averufin (AVR). Although we had previously suggested that this occurs in one enzymatic step, we demonstrate here that this conversion is composed of two enzymatic steps by showing that the two enzyme activities in the cytosol fraction of Aspergillusparasiticus were clearly separated by Mono Q column chromatography. An enzyme
avnA, a gene encoding a cytochrome P-450 monooxygenase, is involved in the conversion of averantin to averufin in aflatoxin biosynthesis in Aspergillus parasiticus
作者:J Yu、P K Chang、J W Cary、D Bhatnagar、T E Cleveland
DOI:10.1128/aem.63.4.1349-1356.1997
日期:1997.4
mutant showed that norsolorinic acid and averantin were not converted to aflatoxin whereas 5'-hydroxyaverantin, averufanin, averufin, versicolorin A. sterigmatocystin, and O-methylsterigmatocystin were converted to aflatoxins. Southern blot analysis of the wild-type strain and avnA-disrupted mutant strain indicated that the avnA gene was disrupted in the mutant strain. A search of the GenBank database
最近的研究表明,至少有17个参与黄曲霉毒素生物合成途径的基因聚集在寄生曲霉基因组的75 kb DNA片段中。一些其他的转录本也已经被定位到这个基因簇。对avnA基因(以前称为ord-1)进行了测序,该基因对应于先前在基因簇上的ver-1和omtA基因之间鉴定的两个转录物之一。avnA基因的核苷酸序列包含一个495个氨基酸的蛋白质的编码区,计算的分子量为56.3 kDa。该基因由三个外显子和两个内含子组成。野生型黄曲霉致寄生性链球菌菌株(SU1-N3)中avnA基因的破坏导致非黄曲霉致突变体,其积累了亮黄色颜料。用六种不同溶剂系统进行的薄层色谱研究表明,累积的代谢物的迁移模式与已知的黄曲霉毒素前体阿维兰汀的迁移模式相同。用该突变体进行的前体摄食研究表明,去甲鸟梨酸和阿维兰汀未转化为黄曲霉毒素,而5'-羟基阿维兰汀,阿维柔宁,阿维柔芬,Versicolorin A. sterigmatocys