PARENT SESSION
Posters P7B Evolution of photosynthesis. Abstracts (579-591)

A novel function of SQDG for growth of Synechocystis sp. PCC6803. Motohide Aoki^*,1, Norihiro Sato¹, Ayano Meguro¹, Mikio Tsuzuki¹, ¹ Tokyo University of Pharmacy and Life Science, Hachioji, Tokyo, Japan

ABSTRACT- The cyanobacterium Synechocystis sp. PCC6803 requires sulfolipid, sulfoquinovosyl diacylglyceride, not only for photosynthesis but also for its growth. Lack of SQDG did not bring about dependency in SQDG-deficient mutants obtained previously from other organisms so far. In order to understand a role of SQDG in growth of Synechocystis sp. PCC6803, the author examined effects of SQDG-deficiency on the physiological properties of the cells during incubation through microscopic and flow cytometry analyses in the sulfolipid-deficient mutant of Synechocystis sp. PCC6803, SD1. In this study, we observed that SQDG-deficiency inhibited cell division and significantly increased average of cell size in SD1 cells during incubation without SQDG, whereas the cell division and cell size did not change in the wild type cells without SQDG and SD1 cells with SQDG-supplementation during incubation. The contents of macromolecules such as DNA and chlorophyll both in the wild type cells without SQDG and SD1 cells supplemented SQDG remained almost constant during incubation 5 days. The contents of macromolecules in SD1 cells during incubation without SQDG were gradually increased till the growth stopped completely. Therefore, it appeared that SD1 cells when SQDG was depleted arrested cell division with continued de novo biosynthesis of the macromolecules. These results suggested that SQDG plays a role not only in photosynthesis but also in cell division of Synechocystis sp. PCC6803.

KEY WORDS: cell division, sulfolipid, cyanobacteria