The ISWI remodeler in plants: protein complexes, biochemical functions, and developmental roles

Imitation Switch (ISWI) is a member of the ATP-dependent chromatin remodeling factor family, whose members move or restructure nucleosomes using energy derived from ATP hydrolysis. ISWI proteins are conserved in eukaryotes and usually form complexes with DDT (DNA-binding homeobox and different transcription factors)-domain proteins. Here, we review recent research on ISWI in the model plant Arabidopsis thaliana (AtISWI). AtISWI forms complexes with AtDDT-domain proteins, many of which have domain structures that differ from those of DDT-domain proteins in yeast and animals. This might suggest that plant ISWI complexes have unique roles. In vivo studies have shown that AtISWI is involved in the formation of the evenly spaced pattern of nucleosome arrangement in gene bodies-this pattern is associated with high transcriptional levels of genes. In addition, AtISWI and the AtDDT-domain protein RINGLET (RLT) are involved in many developmental processes in A. thaliana, including meristem fate transition and organ formation. Studies on the functions of AtISWI may shed light on how chromatin remodeling functions in plants and also provide new information about the evolution of ISWI remodeling complexes in eukaryotes.