Isolation of an scFv targeting BRG1 using phage display with characterization by AFM.

Remodeling of chromatin is a vitally important event in processes such as transcription and replication. Brahma-related gene 1 (BRG1) protein is the major ATPase subunit in the human Swi/Snf complex (hSwi/Snf), an important example of the family of enzymes that carry out such remodeling events. We have used a recently developed technique, recognition imaging, to better understand the role of BRG1 in remodeling chromatin. In such experiments, a specific antibody against BRG1 is needed. However, we have found that the commercially available polyclonal (CAP) antibodies interact non-specifically with nucleosomes, making it impossible to identify hSwi/Snf (BRG1) in their presence. Here antibody phage display technology is employed for development of an antibody specifically targeting BRG1. The Tomlinson I and J single chain variable fragment (scFv) libraries were used for successful isolation of an anti-BRG1 scFv. We demonstrate that the scFv binds more strongly and with less nonspecific interactions than the CAP antibody. This work lays the groundwork for future studies involving chromatin remodeling.