Diverse origins of enzymes involved in the biosynthesis of chloroplast peptidoglycan
Diverse origins of enzymes involved in the biosynthesis of chloroplast peptidoglycan
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DOI：
10.1007/s10265-017-0935-3
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发表时间：
2017-04
影响因子：
2.8
通讯作者：
N. Sato;H. Takano
中科院分区：
文献类型：
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作者：
N. Sato;H. Takano
叶绿体被认为是祖先蓝细菌的后代，其外膜和内膜之间具有肽聚糖层。历史上，蓝藻Cyanophora paradoxa和根足Paulinella chromatophora被认为含有具有肽聚糖的共生蓝藻，通常被称为“蓝藻”。此外，在苔藓植物Physcomitrella patens以及一些植物和藻类中也发现了参与肽聚糖合成的完整基因组。 P 中的新代谢标记技术证明了肽聚糖样结构的存在。专利。然而，许多绿藻和所有已知的红藻缺乏肽聚糖相关基因。这就是我们质疑绿藻和植物叶绿体中肽聚糖合成酶起源的原因。我们利用 Gclust 同源簇和其他基因组数据对参与肽聚糖合成的十种酶进行了系统发育分析。正如预期的那样，所有已识别的基因均在 P. 的色素基因组中编码。色素细胞与蓝藻同系物密切相关。在绿藻和植物中，仅发现两个基因murA和mraY与蓝藻同源基因密切相关。所有其他基因的起源都是不同的。不幸的是，C 的起源。由于已发表的基因组数据不完整，paradoxagenes 尚未明确确定。我们讨论了可能的进化情景，以解释叶绿体肽聚糖生物合成酶的大部分非蓝藻起源：一种可能的进化情景包括绿色植物早期进化过程中广泛的多次水平基因转移。
Chloroplasts are believed to be descendants of ancestral cyanobacteria that had peptidoglycan layer between the outer and the inner membranes. Historically, the glaucophyteCyanophora paradoxaand the rhizopodPaulinella chromatophorawere believed to harbor symbiotic cyanobacteria having peptidoglycan, which were conventionally named “cyanelles”. In addition, the complete set of genes involved in the synthesis of peptidoglycan has been found in the mossPhyscomitrella patensand some plants and algae. The presence of peptidoglycan-like structures was demonstrated by a new metabolic labeling technique inP. patens. However, many green algae and all known red algae lack peptidoglycan-related genes. That is the reason why we questioned the origin of peptidoglycan-synthesizing enzymes in the chloroplasts of the green algae and plants. We performed phylogenetic analysis of ten enzymes involved in the synthesis of peptidoglycan exploiting the Gclust homolog clusters and additional genomic data. As expected, all the identified genes encoded in the chromatophore genome ofP. chromatophorawere closely related to cyanobacterial homologs. In the green algae and plants, only two genes,murAandmraY, were found to be closely related to cyanobacterial homologs. The origins of all other genes were diverse. Unfortunately, the origins ofC. paradoxagenes were not clearly determined because of incompleteness of published genomic data. We discuss on the probable evolutionary scenarios to explain the mostly non-cyanobacterial origins of the biosynthetic enzymes of chloroplast peptidoglycan: A plausible one includes extensive multiple horizontal gene transfers during the early evolution of Viridiplantae.