The linear chromosome of the plant-pathogenic mycoplasma 'Candidatus Phytoplasma mali'.
The linear chromosome of the plant-pathogenic mycoplasma 'Candidatus Phytoplasma mali'.
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DOI：
10.1186/1471-2164-9-306
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发表时间：
2008-06-26
期刊：
影响因子：
4.4
通讯作者：
Seemüller E
中科院分区：
文献类型：
--
作者：
Kube M;Schneider B;Kuhl H;Dandekar T;Heitmann K;Migdoll AM;Reinhardt R;Seemüller E
植物原体是昆虫传播的、不可培养的细菌植物病原体，在数百种重要的经济植物中引起疾病。它们代表了支原体类（俗称支原体）中的单系群体，其特征是基因组小，GC含量低，缺乏坚固的细胞壁。到目前为止，所有的支原体，包括“候选植物原体（Ca.） asteris”和“Ca. P. australiense”的菌株，都有圆形染色体，就像几乎所有的壁细菌一样。本研究表明，苹果增殖病的病原菌马里植原体（Ca. Phytoplasma mali）具有线性染色体。在亲缘关系较近的临时种“Ca. P. pyri”和“Ca. P. prunorum”中也发现了线形染色体。该菌株的染色体长度为601,943 bp， GC含量为21.4%。染色体的进一步特征是大的末端反向重复和共价闭合的发夹端。对蛋白质编码基因的分析表明，“Ca. P. asteris”的主要能量产生途径糖酵解在“Ca. P. mali”中是不完全的。由于支原体中明显缺乏其他代谢途径，因此有人提出麦芽糖和苹果酸盐被用作碳和能量来源。然而，完整的atp生成途径尚未确定。“Ca. P. mali”与“Ca. P. asteris”的不同之处在于，它的基因组更小，GC含量更低，旁系基因数量更少，潜在的可移动DNA元件插入量更少，氨基酸的ABC转运体数量也大大减少。相比之下，“Ca. P. mali”具有比“Ca. P. asteris”更长的同源重组、切除修复和SOS反应基因集。小的线性染色体，末端倒置重复数大，共价闭合的发夹端，极低的GC含量和有限的代谢能力反映了“Ca. P. mali”的独特特征，不仅在植物原体中，而且在所有支原体中。人们期望，在这里获得的基因组信息将有助于更好地理解植物原体代谢的减少，它们对营养的挑剔要求阻碍了无菌培养，以及与致病性有关的机制。
Phytoplasmas are insect-transmitted, uncultivable bacterial plant pathogens that cause diseases in hundreds of economically important plants. They represent a monophyletic group within the class Mollicutes (trivial name mycoplasmas) and are characterized by a small genome with a low GC content, and the lack of a firm cell wall. All mycoplasmas, including strains of 'Candidatus (Ca.) Phytoplasma asteris' and 'Ca. P. australiense', examined so far have circular chromosomes, as is the case for almost all walled bacteria. Our work has shown that 'Ca. Phytoplasma mali', the causative agent of apple proliferation disease, has a linear chromosome. Linear chromosomes were also identified in the closely related provisional species 'Ca. P. pyri' and 'Ca. P. prunorum'. The chromosome of 'Ca. P. mali' strain AT is 601,943 bp in size and has a GC content of 21.4%. The chromosome is further characterized by large terminal inverted repeats and covalently closed hairpin ends. Analysis of the protein-coding genes revealed that glycolysis, the major energy-yielding pathway supposed for 'Ca. P. asteris', is incomplete in 'Ca. P. mali'. Due to the apparent lack of other metabolic pathways present in mycoplasmas, it is proposed that maltose and malate are utilized as carbon and energy sources. However, complete ATP-yielding pathways were not identified. 'Ca. P. mali' also differs from 'Ca. P. asteris' by a smaller genome, a lower GC content, a lower number of paralogous genes, fewer insertions of potential mobile DNA elements, and a strongly reduced number of ABC transporters for amino acids. In contrast, 'Ca. P. mali' has an extended set of genes for homologous recombination, excision repair and SOS response than 'Ca. P. asteris'. The small linear chromosome with large terminal inverted repeats and covalently closed hairpin ends, the extremely low GC content and the limited metabolic capabilities reflect unique features of 'Ca. P. mali', not only within phytoplasmas, but all mycoplasmas. It is expected that the genome information obtained here will contribute to a better understanding of the reduced metabolism of phytoplasmas, their fastidious nutrition requirements that prevented axenic cultivation, and the mechanisms involved in pathogenicity.
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DOI：
10.1073/pnas.97.14.7721
发表时间：
2000-07-05
影响因子：
11.1
作者：
Deneke, J;Ziegelin, G;Lanka, E
通讯作者：
Lanka, E
影响因子：
4.8
作者：
Andersson, U;Levander, F;Rådström, P
通讯作者：
Rådström, P
影响因子：
3.6
作者：
Casjens, S;Murphy, M;Huang, WM
通讯作者：
Huang, WM
影响因子：
14.9
作者：
Himmelreich, R;Hilbert, H;Herrmann, R
通讯作者：
Herrmann, R
影响因子：
10.5
作者：
Bao, K;Cohen, SN
通讯作者：
Cohen, SN