Moss Chloroplasts Are Surrounded by a Peptidoglycan Wall Containing D-Amino Acids
Moss Chloroplasts Are Surrounded by a Peptidoglycan Wall Containing D-Amino Acids
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DOI：
10.1105/tpc.16.00104
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发表时间：
2016-07-01
期刊：
影响因子：
11.6
通讯作者：
Takano, Hiroyoshi
中科院分区：
文献类型：
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作者：
Hirano, Takayuki;Tanidokoro, Koji;Takano, Hiroyoshi
据认为，绿色植物的质体在从内共生蓝藻进化过程中丢失了肽聚糖（即含有d -氨基酸的细菌细胞壁）。尽管在绿色植物的质体中没有检测到壁状结构，但苔藓小壶藓（Physcomitrella patens）具有产生肽聚糖（Mur基因）所需的基因，敲除这些基因会导致叶绿体分裂缺陷。在这里，我们为编码D-Ala:D-Ala连接酶的细菌肽聚糖合成基因产生了P. patens敲除系（Delta Pp-ddl）。Delta pp - dd1具有大叶绿体表型，与其他Mur基因敲除系相似。在培养基中添加D-Ala-D-Ala （DA-DA）抑制了Delta Pp-ddl巨叶绿体的出现，而添加L-Ala-L-Ala （LA-LA）、DA-LA、LA-DA或D-Ala则没有抑制作用。最近，利用乙基da - da（乙基da - da）和点击化学将叠氮修饰的荧光基团连接到乙基上，建立了一种标记细菌肽聚糖的代谢方法。p-ddl和EDA-DA的结果表明，苔藓叶绿体被肽聚糖完全包围。我们的研究结果强烈表明，苔藓质体具有一个含有d -氨基酸的肽聚糖壁。相比之下，在T-DNA标记的拟南芥ddl突变系中未观察到质体表型。
It is believed that the plastids in green plants lost peptidoglycan (i.e., a bacterial cell wall-containing D-amino acids) during their evolution from an endosymbiotic cyanobacterium. Although wall-like structures could not be detected in the plastids of green plants, the moss Physcomitrella patens has the genes required to generate peptidoglycan (Mur genes), and knocking out these genes causes defects in chloroplast division. Here, we generated P. patens knockout lines (Delta Pp-ddl) for a homolog of the bacterial peptidoglycan-synthetic gene encoding D-Ala:D-Ala ligase. Delta Pp-ddl had a macrochloroplast phenotype, similar to other Mur knockout lines. The addition of D-Ala-D-Ala (DA-DA) to the medium suppressed the appearance of giant chloroplasts in Delta Pp-ddl, but the addition of L-Ala-L-Ala (LA-LA), DA-LA, LA-DA, or D-Ala did not. Recently, a metabolic method for labeling bacterial peptidoglycan was established using ethynyl-DA-DA (EDA-DA) and click chemistry to attach an azide-modified fluorophore to the ethynyl group. The Delta Pp-ddl line complemented with EDA-DA showed that moss chloroplasts are completely surrounded by peptidoglycan. Our findings strongly suggest that the moss plastids have a peptidoglycan wall containing D-amino acids. By contrast, no plastid phenotypes were observed in the T-DNA tagged ddl mutant lines of Arabidopsis thaliana.