The host-switching mechanism of phytoplasmas between plants and animals towards the elucidation of the host determination system

植原体在植物和动物之间的宿主转换机制，阐明宿主决定系统

基本信息

批准号：
13306004
负责人：
NAMBA Shigetou
金额：
$ 24.13万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2003
项目状态：
已结题

项目摘要

In this year, we determined the complete genomic sequence of the plant-pathogenic bacterium Candidatus Phytoplasma asteris. Comparison of the genome of P.asteris with those of other parasitic and symbiotic bacteria reveals features that are unique to this intracellular parasite, which has adapted to a nutrient-rich environment. The genome of P.asteris encodes genes for basic functions, such as DNA replication, transcription, and translation. In contrast, genes responsible for amino acid and fatty acid biosynthesis, the TCA cycle, and oxidative phosphorylation are absent. This may be because phytoplasmas can depend on their host cells for supplies of many biological substances, as is the case with mycoplasmas. Surprisingly, the P.asteris genome encodes proteins for even fewer metabolic functions than do those of mycoplasmas. For example, the genes for the pentose phosphate cycle and ATP synthase have not been found. R.prowazekii has also lost the genes for the pentose phosphate cycle ; however, this organism has retained genes for the TCA cycle, electron transfer system, and ATP synthase. The complete P.asteris genome suggests that the set of known metabolic pathways of phytoplasmas is even smaller than that of mycoplasmas, representing the most minimal genome among living organisms. Instead, P.asteris possesses genes for transporter proteins involved in the uptake of substances from the surrounding host cell cytoplasm. This may be the result of reductive evolution, as a consequence of life as an intracellular parasite in a nutrient-rich environment Phytoplasmas are unique bacteria that contain a new minimal gene set, and this finding should help to elucidate the host determination mechanisms of phytoplasmas.

在今年，我们确定了植物性疾病细菌念珠菌绿色星座的完整基因组序列。 P.asteris的基因组与其他寄生虫和共生细菌的基因组的比较揭示了这种细胞内寄生虫所独有的特征，该特征已适合于营养丰富的环境。 P.asteris的基因组编码基因的基因，例如DNA复制，转录和翻译。相反，不存在负责氨基酸和脂肪酸生物合成，TCA循环和氧化磷酸化的基因。可能是因为植物质体可以取决于其宿主细胞的许多生物学物质的供应，就像支原体一样。令人惊讶的是，P.asteris基因组对蛋白质的代谢功能的编码甚至比分枝杆菌的代谢功能更少。例如，尚未找到五肽磷酸循环和ATP合酶的基因。 R.prowazekii也丢失了五磷酸五磷酸五肽周期的基因。但是，该生物已经保留了TCA循环，电子转移系统和ATP合酶的基因。完整的p.asteris基因组表明，植物植物的已知代谢途径的集合甚至比支原体小，代表了活生物体中最小的基因组。取而代之的是，p.asteris具有参与周围宿主细胞细胞质吸收的转运蛋白的基因。这可能是还原性进化的结果，这是生命作为富含营养的环境植物质体中细胞内寄生虫的结果，是含有新的最小基因集的独特细菌，这一发现应有助于阐明植物质体的宿主确定机制。