RRC ID 28754
Author Miyagishima SY, Suzuki K, Okazaki K, Kabeya Y.
Title Expression of the nucleus-encoded chloroplast division genes and proteins regulated by the algal cell cycle.
Journal Mol Biol Evol
Abstract Chloroplasts have evolved from a cyanobacterial endosymbiont and their continuity has been maintained by chloroplast division, which is performed by the constriction of a ring-like division complex at the division site. It is believed that the synchronization of the endosymbiotic and host cell division events was a critical step in establishing a permanent endosymbiotic relationship, such as is commonly seen in existing algae. In the majority of algal species, chloroplasts divide once per specific period of the host cell division cycle. In order to understand both the regulation of the timing of chloroplast division in algal cells and how the system evolved, we examined the expression of chloroplast division genes and proteins in the cell cycle of algae containing chloroplasts of cyanobacterial primary endosymbiotic origin (glaucophyte, red, green, and streptophyte algae). The results show that the nucleus-encoded chloroplast division genes and proteins of both cyanobacterial and eukaryotic host origin are expressed specifically during the S phase, except for FtsZ in one graucophyte alga. In this glaucophyte alga, FtsZ is persistently expressed throughout the cell cycle, whereas the expression of the nucleus-encoded MinD and MinE as well as FtsZ ring formation are regulated by the phases of the cell cycle. In contrast to the nucleus-encoded division genes, it has been shown that the expression of chloroplast-encoded division genes is not regulated by the host cell cycle. The endosymbiotic gene transfer of minE and minD from the chloroplast to the nuclear genome occurred independently on multiple occasions in distinct lineages, whereas the expression of nucleus-encoded MIND and MINE is regulated by the cell cycle in all lineages examined in this study. These results suggest that the timing of chloroplast division in algal cell cycle is restricted by the cell cycle-regulated expression of some but not all of the chloroplast division genes. In addition, it is suggested that the regulation of each division-related gene was established shortly after the endosymbiotic gene transfer, and this event occurred multiple times independently in distinct genes and in distinct lineages.
Volume 29(10)
Pages 2957-70
Published 2012-10-1
DOI 10.1093/molbev/mss102
PII mss102
PMID 22490821
MeSH Algal Proteins / genetics* Algal Proteins / metabolism Cell Cycle / genetics* Cell Nucleus / genetics* Chlamydomonas reinhardtii / cytology Chlamydomonas reinhardtii / genetics Chloroplasts / genetics* Cyanobacteria / genetics Eukaryota / cytology Eukaryota / genetics* Gene Expression Regulation* Gene Transfer, Horizontal / genetics Genes, Chloroplast / genetics* Glaucophyta / cytology Glaucophyta / genetics Rhodophyta / cytology Rhodophyta / genetics Symbiosis / genetics Time Factors
IF 11.062
Times Cited 32
Algae NIES-2170 NIES-484 NIES-1332 NIES-296 NIES-547