Moss Chloroplasts Are Surrounded by a Peptidoglycan Wall Containing D-Amino Acids.
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 (∆Pp-ddl) for a homolog of the bacterial peptidoglycan-synthetic gene encoding d-Ala:d-Ala ligase. ∆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 ∆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 ∆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.
Graduate School of Science and Technology, Kumamoto University, Kumamoto 860-8555, Japan.
Takayuki
T
Hirano
Graduate School of Science and Technology, Kumamoto University, Kumamoto 860-8555, Japan.
Koji
K
Tanidokoro
Faculty of Agriculture, Kyushu University, Fukuoka 812-8581, Japan.
Yasuhiro
Y
Shimizu
Faculty of Agriculture, Kyushu University, Fukuoka 812-8581, Japan National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8566, Japan.
Yutaka
Y
Kawarabayasi
Faculty of Engineering, Osaka Institute of Technology, Asahi-ku, Osaka 535-8585, Japan.
Toshihisa
T
Ohshima
Graduate School of Science and Technology, Kumamoto University, Kumamoto 860-8555, Japan.
Momo
M
Sato
Graduate School of Science and Technology, Kumamoto University, Kumamoto 860-8555, Japan.
Shinji
S
Tadano
Graduate School of Science and Technology, Kumamoto University, Kumamoto 860-8555, Japan.
Hayato
H
Ishikawa
Graduate School of Science and Technology, Kumamoto University, Kumamoto 860-8555, Japan Center for Marine Environment Studies, Kumamoto University, Kumamoto 860-8555, Japan.
Susumu
S
Takio
Graduate School of Science and Technology, Kumamoto University, Kumamoto 860-8555, Japan.
Katsuaki
K
Takechi
Graduate School of Science and Technology, Kumamoto University, Kumamoto 860-8555, Japan Institute of Pulsed Power Science, Kumamoto University, Kumamoto 860-8555, Japan takano@kumamoto-u.ac.jp.
Hiroyoshi
H
Takano
D000596:Amino Acids / Q000378:metabolism*; D017360:Arabidopsis / Q000378:metabolism; D019068:Bryopsida / Q000378:metabolism*; D002736:Chloroplasts / Q000378:metabolism*; D057930:Click Chemistry; D004269:DNA, Bacterial / Q000378:metabolism; D010457:Peptidoglycan / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D018087:Plastids / Q000378:metabolism
D000596:Amino Acids; D004269:DNA, Bacterial; D010457:Peptidoglycan; D010940:Plant Proteins; C036483:T-DNA