InterPro domain: IPR025344

This domain corresponds to the C-terminal intermembrane space (IMS) region from Protein ACCUMULATION AND REPLICATION OF CHLOROPLASTS 6 (ARC6) and its paralogue PARC6 [ 1 ]. ARC6 and PARC6 are components of the plastid division machinery which are essential for the chloroplast replication process [ 2 , 2 ], which implies the assembly and constriction of the tubulin-like FtsZ ring on the stromal surface of the inner envelope membrane (IEM) and the dynamin-like ARC5 ring on the cytosolic surface of the outer envelope membrane (OEM). ARC6 is evolutionarily related to the cyanobacterial cell division protein Ftn2/ZipN [ 3 ], having similar structures. This domain from ARC6 and PARC6 interacts with PDV2 and PDV1 respectively. PDV proteins recruit dynamin-like ARC5 ring to the chloroplast surface and mediate its constriction. ARC6/PARC6 are key to connect and coordinate FtsZ and ARC5 rings during fission [ 3 , 4 ].

1. Crystal structure of a conserved domain in the intermembrane space region of the plastid division protein ARC6. Protein Sci 25, 523-9
2. Roles of Arabidopsis PARC6 in Coordination of the Chloroplast Division Complex and Negative Regulation of FtsZ Assembly. Plant Physiol 170, 250-62
3. Arabidopsis ARC6 coordinates the division machineries of the inner and outer chloroplast membranes through interaction with PDV2 in the intermembrane space. Plant Cell 20, 2460-70
4. Arabidopsis PARC6 Is Critical for Plastid Morphogenesis in Pavement, Trichome, and Guard Cells in Leaf Epidermis. Front Plant Sci 10, 1665