Heck Karina, Alvarenga Danillo O, Shishido Tania K, Varani Alessandro M, Dörr Felipe A, Pinto Ernani, Rouhiainen Leo, Jokela Jouni, Sivonen Kaarina, Fiore Marli F
University of São Paulo (USP), Center for Nuclear Energy in Agriculture, Piracicaba, SP, Brazil.
University of São Paulo (USP), Center for Nuclear Energy in Agriculture, Piracicaba, SP, Brazil; São Paulo State University (UNESP), College of Agricultural and Veterinary Science, Department of Technology, Jaboticabal, SP, Brazil.
Toxicon. 2018 Jan;141:43-50. doi: 10.1016/j.toxicon.2017.10.021. Epub 2017 Nov 27.
Microcystins (MCs) are serine/threonine phosphatase inhibitors synthesized by several members of the phylum Cyanobacteria. Mining the draft genome sequence of the nostocalean MC-producing Fischerella sp. strain CENA161 led to the identification of three contigs containing mcy genes. Subsequent PCR and Sanger sequencing allowed the assembling of its complete biosynthetic mcy gene cluster with 55,016 bases in length. The cluster encoding ten genes (mcyA-J) with a central bidirectional promoter was organized in a similar manner as found in other genera of nostocalean cyanobacteria. However, the nucleotide sequence of the mcy gene cluster of Fischerella sp. CENA161 showed significant differences from all the other MC-producing cyanobacterial genera, sharing only 85.2 to 74.1% identities. Potential MC variants produced by Fischerella sp. CENA161 were predicted by the analysis of the adenylation domain binding pockets and further investigated by LC-MS/MS analysis. To our knowledge, this study presents the first complete mcy cluster characterization from a strain of the genus Fischerella, providing new insight into the distribution and evolution of MCs in the phylum Cyanobacteria.
微囊藻毒素（MCs）是由蓝藻门的几个成员合成的丝氨酸/苏氨酸磷酸酶抑制剂。对产微囊藻毒素的念珠藻科费氏藻属菌株CENA161的基因组草图序列进行挖掘，发现了3个含有mcy基因的重叠群。随后通过PCR和桑格测序，组装出了其完整的长度为55,016个碱基的生物合成mcy基因簇。该基因簇编码10个基因（mcyA-J），有一个中央双向启动子，其组织方式与念珠藻科其他属的蓝藻中发现的类似。然而，费氏藻属菌株CENA161的mcy基因簇的核苷酸序列与所有其他产微囊藻毒素的蓝藻属存在显著差异，同一性仅为85.2%至74.1%。通过对腺苷化结构域结合口袋的分析预测了费氏藻属菌株CENA161产生的潜在微囊藻毒素变体，并通过液相色谱-串联质谱分析进行了进一步研究。据我们所知，本研究首次对费氏藻属菌株的完整mcy基因簇进行了表征，为微囊藻毒素在蓝藻门中的分布和进化提供了新的见解。
