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App Envir Micro:蒋永光等蓝藻毒素合成基因研究获新进展

  1. App Envir Micro
  2. 尖头藻
  3. 毒素合成基因
  4. 蓝藻

来源:中科院水生生物研究所 2012-11-18 13:18

近日,国际著名杂志Applied and Environmental Microbiology在线刊登了中科院水生生物研究所研究人员的最新研究成果“Molecular Basis and Phylogenetic Implications of Deoxycylindrospermopsin Biosynthesis in the Cyanobacterium Raphidiopsis curva

近日,国际著名杂志Applied and Environmental Microbiology在线刊登了中科院水生生物研究所研究人员的最新研究成果“Molecular Basis and Phylogenetic Implications of Deoxycylindrospermopsin Biosynthesis in the Cyanobacterium Raphidiopsis curvata,”,在研究中,研究者在蓝藻毒素合成基因研究上获得了新的进展。

随着淡水水体富营养化的加剧,蓝藻水华尤其是微囊藻水华问题已经得到了广泛关注和深入研究。目前,国际上对拟柱胞藻水华以及该藻产生的拟柱胞藻毒素(Cylindrospermopsin, CYN)的报道日益增多。但是,我国对于此类拟柱胞藻引起的水华现象研究甚少。CYN是一种两性离子生物碱,能够引起人体肝、肾等多个器官的损伤和细胞坏死。除拟柱胞藻外,其它蓝藻如尖头藻、束丝藻、鱼腥藻、颤藻等均有产生CYN的种类。

由于CYN的产生对居民健康存在潜在的危害,中国科学院水生生物研究所博士研究生蒋永光在李仁辉研究员的指导下开展了相关研究,在CYN生物合成的分子机理方面取得了新进展。

尖头藻是拟柱胞藻的近缘种类,两者常共存于同一水体中。蒋永光等人利用从湖北蕲春赤东湖分离到一株含有脱氧拟柱胞藻毒素(deoxy-CYN)的尖头藻,克隆并测定了该藻株的CYN生物合成基因簇(cyr cluster)的全序列。研究发现,在该藻株中,cyrI基因内部含有92bp的插入序列,阅读框发生移码突变。研究人员推测,正是这一突变导致细胞内CYN合成终止在deoxy-CYN阶段。该发现为cyrI基因功能确认提供了证据。

该研究加深了对拟柱胞藻毒素生物合成的分子机理以及合成基因进化的了解,为拟柱胞藻和尖头藻的系统关系研究提供了新的证据,并为开展拟柱胞藻毒素的分子检测、监测和预警奠定了基础。

该研究得到了国家基础研究973计划、国家自然科学基金、国家重大科技水专项和中科院“百人计划”项目的资助。(生物谷Bioon.com)

Molecular Basis and Phylogenetic Implications of Deoxycylindrospermopsin Biosynthesis in the Cyanobacterium Raphidiopsis curvata

Yongguang Jianga,b, Peng Xiaoa,b, Gongliang Yua, Tomoharu Sanoc, Qianqian Pana,b and Renhui Lia

New insights into the distribution and biochemistry of the cyanotoxin cylindrospermopsin (CYN) have been provided by the recent determination of its biosynthesis gene cluster (cyr) in several cyanobacterial species. Raphidiopsis curvata CHAB1150 isolated from China was analyzed for CYN analogues. Only 7-deoxy-CYN was detected in the cell extracts. The cyr gene cluster of R. curvata CHAB1150 was sequenced, and the cyr genes of this strain were found to have extremely high similarities (96% to 100%) to those from other nostocalean species. These species include Cylindrospermopsis raciborskii AWT205, Aphanizomenon sp. strain 10E6, and Aphanizomenon ovalisporum ILC-146. Insertion mutation was identified within the cyrI gene, and transcripts of cyrI and another functional gene cyrJ were detected in R. curvata CHAB1150. General congruence between the phylogenetic trees based on both cyr and 16S rrn was displayed. Neutral evolution was found on the whole sequences of the cyr genes, and 0 to 89 negative selected codons were detected in each gene. Therefore, the function of CyrI is to catalyze the oxygenation of 7-deoxy-CYN in CYN biosynthesis. The transcripts of the mutated cyrI gene may result from polycistronic transcription. The high conservation of the cyr genes may be ascribed to purifying selection and horizontal gene transfer.

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