Journal of Plant Research

, Volume 130, Issue 4, pp 635–645

Diverse origins of enzymes involved in the biosynthesis of chloroplast peptidoglycan

Regular Paper

DOI: 10.1007/s10265-017-0935-3

Cite this article as:
Sato, N. & Takano, H. J Plant Res (2017) 130: 635. doi:10.1007/s10265-017-0935-3

Abstract

Chloroplasts are believed to be descendants of ancestral cyanobacteria that had peptidoglycan layer between the outer and the inner membranes. Historically, the glaucophyte Cyanophora paradoxa and the rhizopod Paulinella chromatophora were 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 moss Physcomitrella patens and some plants and algae. The presence of peptidoglycan-like structures was demonstrated by a new metabolic labeling technique in P. 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 of P. chromatophora were closely related to cyanobacterial homologs. In the green algae and plants, only two genes, murA and mraY, were found to be closely related to cyanobacterial homologs. The origins of all other genes were diverse. Unfortunately, the origins of C. paradoxa genes 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.

Keywords

Chloroplast evolution Cyanophora paradoxa Endosymbiosis Paulinella chromatophora Peptidoglycan Viridiplantae 

Supplementary material

10265_2017_935_MOESM1_ESM.pdf (5.1 mb)
Supplementary material 1 (PDF 5213 KB)
10265_2017_935_MOESM2_ESM.zip (281 kb)
Supplementary material 2 (ZIP 281 KB)

Funding information

Funder NameGrant NumberFunding Note
Ministry of Education, Culture, Sports, Science and Technology
  • 24570043,15K12433,25440158

Copyright information

© The Botanical Society of Japan and Springer Japan 2017

Authors and Affiliations

  1. 1.Department of Life Sciences, Graduate School of Arts and SciencesUniversity of TokyoTokyoJapan
  2. 2.Faculty of Advanced Science and TechnologyKumamoto UniversityKumamotoJapan
  3. 3.Institute of Pulsed Power ScienceKumamoto UniversityKumamotoJapan

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