Abstract: Localization and function of ARC6 in cell division

Chloroplast division of photosynthetic eukaryotes is a highly regulated process with divisionary machinery involving a division ring and other essential components. To gain insights into this process, our lab uses the green alga Chlamydomonas reinhardtii, which possesses a single chloroplast that coordinates with the rest of the cell during division. We investigate the role of the ARC6 protein, a potential linker between the inner chloroplast membrane and the FtsZ division ring. We aim to investigate the dynamics of ARC6 localization and its potential role in the context of various division components and the FtsZ ring. While previous studies have indicated that ARC6 localizes at the division site, the underlying mechanisms and its relationship with FtsZ and other divisionary machinery are not fully understood. In our study, by employing fluorescent microscopy, we characterized the localization patterns of ARC6 during cell division. Our findings reveal a dynamic assembly and disassembly behavior of ARC6 at the division site, enabling movement along the chloroplast membrane to subsequent division sites. Previous research has suggested that cytoskeletal actin may be important for the formation of the inner division ring. Surprisingly, we found an apparent loss of ARC6 at the division site in the absence of actin in our experiments. This result suggests that the cell uses the cytoplasmic F-actin to regulate the localization of ARC6 in the chloroplast inner envelope. Possible mechanisms for this regulation and the consequences of loss of ARC6 from the division site are being examined.