Massive genome erosion and functional adaptations provide insights into the symbiotic lifestyle of Sodalis glossinidius in the tsetse host
Massive genome erosion and functional adaptations provide insights into the symbiotic lifestyle of Sodalis glossinidius in the tsetse host
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DOI：
10.1101/gr.4106106
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发表时间：
2006-02-01
期刊：
影响因子：
7
通讯作者：
Aksoy, S
中科院分区：
文献类型：
--
作者：
Toh, H;Weiss, BL;Aksoy, S
Sodalis Glossinidius 是采采蝇 (Glossina spp.) 母系传播的内共生体，采采蝇是一种具有医学和兽医意义的昆虫。对 Sodalis 染色体的完整序列（4,171,146 bp，编码 2,432 个蛋白质编码序列）的分析表明编码能力降低了 51%。此外，染色体包含 972 个假基因，与其他细菌物种相比，这个数字非常高。这些假基因中很大一部分是已知蛋白质的同源物，这些蛋白质在防御或碳水化合物和无机离子的运输和代谢中发挥作用，这表明 Sodalis 对宿主的免疫和受限营养状况的退化适应。 Sodalis 拥有三个染色体共生区 (SSR)：SSR-1、SSR-2 和 SSR-3，其基因库分别与小肠炎耶尔森氏菌的 III 型分泌系统 (TTSS) ysa 和沙门氏菌的 SPI-1 和 SPI-2 相似。虽然针结构的核心成分得到了保留，但在 Sodalis 中，一些通常与病原微生物中的这些系统相关的效应器和调节器被修改或消除。对宿主发育过程中 Sodalis 中 SSR 特异性 invA 转录本丰度的分析表明，各个共生区域可能表现出不同的时间表达谱。此外，Sodalis染色体编码完整的鞭毛结构，其关键成分在未成熟的宿主发育阶段表达。这些特征可能对于子宫内后代共生感染的传播和建立很重要。数据表明，索达里斯代表了从自由生活到共生生活方式的所有进化中间过渡。
Sodalis glossinidius is a maternally transmitted endosymbiont of tsetse flies (Glossina spp.), an insect of medical and veterinary significance. Analysis of the complete sequence of Sodalis' chromosome (4,171,146 bp, encoding 2,432 protein coding sequences) indicates a reduced coding capacity of 51%. Furthermore, the chromosome contains 972 pseudogenes, an inordinately high number compared with that of other bacterial species. A high proportion of these pseudogenes are homologs of known proteins that function either in defense or in the transport and metabolism of carbohydrates and inorganic ions, suggesting Sodalis' degenerative adaptations to the immunity and restricted nutritional status of the host. Sodalis possesses three chromosomal symbiosis regions (SSR): SSR-1, SSR-2, and SSR-3, with gene inventories similar to the Type-III secretion system (TTSS) ysa from Yersinia enterolitica and SPI-1 and SPI-2 from Salmonella, respectively. While core components of the needle structure have been conserved, some of the effectors and regulators typically associated with these systems in pathogenic microbes are modified or eliminated in Sodalis. Analysis of SSR-specific invA transcript abundance in Sodalis during host development indicates that the individual symbiosis regions may exhibit different temporal expression profiles. In addition, the Sodalis chromosome encodes a complete flagella structure, key components of which are expressed in immature host developmental stages. These features may be important for the transmission and establishment of symbiont infections in the intra-uterine progeny. The data Suggest that Sodalis represents ail evolutionary intermediate transitioning from a free-living to a mutualistic lifestyle.