Chromatin Structure Remodeling (RSC) Complex

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File:RSC AFM Images.jpg
AFM images showing single RSC complexes bound to dsDNA. The center and right images show RSC-generated DNA loops.

RSC is a 15-subunit complex with the capacity to remodel the structure of chromatin. It exhibits a DNA-dependent ATPase activity stimulated by both free and nucleosomal DNA and a capacity to perturb nucleosome structures. It is at least 10-fold more abundant than the SWI/SNF complex and is essential for mitotic growth.[1]

Generation of Loops in dsDNA

A single molecule study using magnetic tweezers has observed that RSC generates DNA loops in vitro while simultaneously generating negative supercoils in the template.[2] The figure shows three AFM images from that study. On the left, a single RSC complex is bound to the end of a dsDNA template. The center image shows a DNA loop generated by RSC. The image on the right shows a loop generated by RSC which contains supercoils. The current model of translocation on dsDNA is shown in the figure below, whereby RSC binds the DNA at two locations. Hydrolysis of ATP allows the complex to translocate the DNA into a loop. RSC can release the loop either by translocating back to the original state at a comparable velocity, or by losing one of its two contacts.

File:RSC Translocation Model.jpg
The current model for RSC translocation on dsDNA, proposed by Cairns et al.

RSC components

The following is list of RSC components that have been identified in yeast and the corresponding human orthologs:

yeast human function
RSC1
RSC2
RSC3
RSC4
RSC6 SMARCD1, SMARCD2, SMARCD3
RSC7
RSC8 SMARCC1, SMARCC2
RSC9
RSC11
RSC12
RSC14
RSC30
RSC58

See also

References

  1. Cairns BR, Lorch Y, Li Y, Zhang M, Lacomis L, Erdjument-Bromage H, Tempst P, Du J, Laurent B, Kornberg RD (1996). "RSC, an essential, abundant chromatin-remodeling complex". Cell. 87 (7): 1249–60. doi:10.1016/S0092-8674(00)81820-6. PMID 8980231.
  2. Lia G, Praly E, Ferreira H, Stockdale C, Tse-Dinh YC, Dunlap D, Croquette V, Bensimon D, Owen-Hughes T (2006). "Direct observation of DNA distortion by the RSC complex". Mol. Cell. 21 (3): 417–25. doi:10.1016/j.molcel.2005.12.013. PMID 16455496.

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