Architecture of the SWI/SNF-Nucleosome Complex

Abstract

The SWI/SNF complex disrupts and mobilizes chromatin in an ATP-dependent manner. SWI/SNF interactions with nucleosomes were mapped by DNA footprinting and site-directed DNA and protein cross-linking when SWI/SNF was recruited by a transcription activator. SWI/SNF was found by DNA footprinting to contact tightly around one gyre of DNA spanning ϳ50 bp from the nucleosomal entry site to near the dyad axis. The DNA footprint is consistent with nucleosomes binding to an asymmetric trough of SWI/SNF that was revealed by the improved imaging of free SWI/SNF. The DNA site-directed cross-linking revealed that the catalytic subunit Swi2/Snf2 is associated with nucleosomes two helical turns from the dyad axis and that the Snf6 subunit is proximal to the transcription factor recruiting SWI/SNF. The highly conserved Snf5 subunit associates with the histone octamer and not with nucleosomal DNA. The model of the binding trough of SWI/SNF illustrates how nucleosomal DNA can be mobilized while SWI/SNF remains bound.

SET Domains of Histone Methyltransferases Recognize ISWI-Remodeled Nucleosomal Species

“…The increased DNase I sensitivity suggests that SWI/SNF disrupts the structure of nucleosome. The differences in DNase I di- gestion patterns of SWI/SNF-and ISW2-remodeled nucleosomes are consistent with published work on the activities of these two complexes (11,12,24). The failure of SWI/SNF to stimulate SET domain binding to nucleosomes was surprising, so we further verified the remodeling of the template by using a RE accessibility assay.…”

“…In addition to Isw2, we remodeled dinucleosomes with Isw1a, Isw1b, and SWI/SNF. Isw2, Isw1a, and Isw1b slide nucleosomes to new positions but display different biochemical properties and, thus, will generate different remodeled species (11,13). Interestingly, remodeling by Isw1a and Isw1b generated different products, which was dependent upon the length of the spacer DNA.…”

Purification of protein–DNA complexes by native gel electrophoresis for electron microscopy study

“…Особую роль в процессе ремоделиро-вания выполняют N-концевые участки гистонов, наиболее часто подвергающиеся посттрансляцион-ным модификациям. Они практически не структу-рированы и выходят за границу нукеосомы, обес-печивая взаимодействия с ДНК и различными белковыми факторами [5].При АТФ-зависимом ремоделировании хрома-тина могут образовываться динуклеосомы [6]. Пе-рестройки хроматина, сборка и разборка нуклеосом сопровождают все процессы, происходящие с учас-тием генетического материала в клетке.…”

“…При АТФ-зависимом ремоделировании хрома-тина могут образовываться динуклеосомы [6]. Пе-рестройки хроматина, сборка и разборка нуклеосом сопровождают все процессы, происходящие с учас-тием генетического материала в клетке.…”

“…№ 1. C. [3][4][5][6][7][8] нена в связи с большими размерами и структурной лабильностью. Поэтому основным методом полу-чения структурной информации в данном случае служит просвечивающая электронная микроскопия (ПЭМ) макромолекул [10].…”