Isolation and investigation of the role of HMG1 in diepoxide cross-link recognition

Tiffany Frazar, Colby College

Document Type Honors Thesis (Open Access)


The most well characterized group of nonhistone chromosomal proteins are the high mobility group (HMG) proteins, which are involved in nonspecific DNA binding and packaging of DNA. HMG1 binds preferentially to distorted DNA, including adducts formed by the anti-tumor drug cisplatin. While HMG1 has been shown to recognize both cisplatin DNA intrastrand and interstrand cross-links, it does not recognize lesions induced by the trans isomer of cisplatin, which is clinically inactive. Thus, cisplatin' s chemotherapeutic abilities are thought to involve cross-link recognition by HMG1, blockage of nucleotide excision repair, and cell death. Diepoxyalkanes such as diepoxybutane may also induce structural alterations in DNA upon cross-linking. In order to determine if HMG1 binds to diepoxide cross-linked DNA, HMGl was first isolated from chicken erythrocytes using salt extraction techniques and chromatography. Gel-shift assays were performed to determine the extent of HMG1 binding to diepoxide cross-linked DNA. Under our current reaction conditions, HMG proteins isolated from chicken erythrocytes appear to bind to a fragment of 5S DNA equally in the control and cross-linked states.