The smallest known genomes of multicellular and toxic cyanobacteria: comparison, minimal gene sets for linked traits and the evolutionary implications.
The smallest known genomes of multicellular and toxic cyanobacteria: comparison, minimal gene sets for linked traits and the evolutionary implications.
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DOI：
10.1371/journal.pone.0009235
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发表时间：
2010-02-16
期刊：
影响因子：
3.7
通讯作者：
Glöckner G
中科院分区：
文献类型：
--
作者：
Stucken K;John U;Cembella A;Murillo AA;Soto-Liebe K;Fuentes-Valdés JJ;Friedel M;Plominsky AM;Vásquez M;Glöckner G
蓝藻形态多样，从单细胞球体或杆到多细胞结构，如菌落和细丝。多细胞物种代表了一种进化策略，将某些生殖和固氮的代谢功能分化和区室化为专门的细胞类型（例如无动细胞，异形胞和固氮细胞）。只有少数丝状的，分化的蓝藻物种，基因组大小超过5 Mb，已被测序。我们对两种密切相关的丝状蓝藻物种的基因组进行了测序，以进一步了解N2固定，丝状体形成和细胞分化特征的分子基础。raciborskii CS-505是来自澳大利亚的产圆柱精子蛋白酶的菌株，而来自巴西的Raphidiopsis brookii D9合成与麻痹性贝类中毒（PSP）相关的神经毒素。尽管它们不同的形态，毒素成分和间断的地理分布，这些菌株形成一个单系群。基因组大小约为3.9（CS-505）和3.2（D9）Mb，这是自由生活的丝状蓝藻所描述的最小基因组。我们观察到显着的基因顺序保守（同线性），这些基因组之间的差异，尽管重复元件的内容，这占了大部分的基因组大小之间的差异。我们在这里表明，菌株共享一组特定的2539个基因，平均核苷酸同一性>90%。CS-505和D9基因组与其他丝状蓝藻物种的基因组相比是小的和流线型的，并且在菌株D9中缺乏形成异形胞的能力，这一事实使我们能够定义负责丝状物种中每个性状的核心基因组。我们推测，在菌株D9的能力，形成适当的异形胞是次要的损失连同固氮能力。进一步比较所有可用的蓝藻基因组，几乎涵盖了整个进化分支揭示了一个共同的最小基因集，这些蓝藻性状。
Cyanobacterial morphology is diverse, ranging from unicellular spheres or rods to multicellular structures such as colonies and filaments. Multicellular species represent an evolutionary strategy to differentiate and compartmentalize certain metabolic functions for reproduction and nitrogen (N2) fixation into specialized cell types (e.g. akinetes, heterocysts and diazocytes). Only a few filamentous, differentiated cyanobacterial species, with genome sizes over 5 Mb, have been sequenced. We sequenced the genomes of two strains of closely related filamentous cyanobacterial species to yield further insights into the molecular basis of the traits of N2 fixation, filament formation and cell differentiation. Cylindrospermopsis raciborskii CS-505 is a cylindrospermopsin-producing strain from Australia, whereas Raphidiopsis brookii D9 from Brazil synthesizes neurotoxins associated with paralytic shellfish poisoning (PSP). Despite their different morphology, toxin composition and disjunct geographical distribution, these strains form a monophyletic group. With genome sizes of approximately 3.9 (CS-505) and 3.2 (D9) Mb, these are the smallest genomes described for free-living filamentous cyanobacteria. We observed remarkable gene order conservation (synteny) between these genomes despite the difference in repetitive element content, which accounts for most of the genome size difference between them. We show here that the strains share a specific set of 2539 genes with >90% average nucleotide identity. The fact that the CS-505 and D9 genomes are small and streamlined compared to those of other filamentous cyanobacterial species and the lack of the ability for heterocyst formation in strain D9 allowed us to define a core set of genes responsible for each trait in filamentous species. We presume that in strain D9 the ability to form proper heterocysts was secondarily lost together with N2 fixation capacity. Further comparisons to all available cyanobacterial genomes covering almost the entire evolutionary branch revealed a common minimal gene set for each of these cyanobacterial traits.
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影响因子：
11.3
作者：
Juhas M;van der Meer JR;Gaillard M;Harding RM;Hood DW;Crook DW
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Crook DW
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