An Arabidopsis homolog of the bacterial peptidoglycan synthesis enzyme MurE has an essential role in chloroplast development
Article first published online: 23 NOV 2007
© 2008 The Authors
The Plant Journal
Volume 53, Issue 6, pages 924–934, March 2008
How to Cite
Garcia, M., Myouga, F., Takechi, K., Sato, H., Nabeshima, K., Nagata, N., Takio, S., Shinozaki, K. and Takano, H. (2008), An Arabidopsis homolog of the bacterial peptidoglycan synthesis enzyme MurE has an essential role in chloroplast development. The Plant Journal, 53: 924–934. doi: 10.1111/j.1365-313X.2007.03379.x
- Issue published online: 23 NOV 2007
- Article first published online: 23 NOV 2007
- Received 22 September 2007; revised 9 November 2007; accepted 14 November 2007.
- chloroplast development;
- pale-green phenotype;
Enzymes encoded by bacterial MurE genes catalyze the ATP-dependent formation of uridine diphosphate-N-acetylmuramic acid-tripeptide in bacterial peptidoglycan biosynthesis. The Arabidopsis thaliana genome contains one gene with homology to the bacterial MurE:AtMurE. Under normal conditions AtMurE is expressed in leaves and flowers, but not in roots or stems. Sequence-based predictions and analyses of GFP fusions of the N terminus of AtMurE, as well as the full-length protein, suggest that AtMurE localizes to plastids. We identified three T-DNA-tagged and one Ds-tagged mutant alleles of AtMurE in A. thaliana. All four alleles show a white phenotype, and A. thaliana antisense AtMurE lines showed a pale-green phenotype. These results suggest that AtMurE is involved in chloroplast biogenesis. Cells of the mutants were inhibited in thylakoid membrane development. RT-PCR analysis of the mutant lines suggested that the expression of genes that depend on a multisubunit plastid-encoded RNA polymerase was decreased. To analyze the functional relationships between the MurE genes of cyanobacteria, the moss Physcomitrella patens and higher plants, a complementation assay was carried out with a P. patens (Pp) MurE knock-out line, which exhibits a small number of macrochloroplasts per cell. Although the Anabaena MurE, fused with the N-terminal region of PpMurE, complemented the macrochloroplast phenotype in P. patens, transformation with AtMurE did not complement this phenotype. These results suggest that AtMurE is functionally divergent from the bacterial and moss MurE proteins.