High affinity MAR-DNA binding is a common property of murine and human mutant p53

Abstract

We recently reported that murine MethA mutant but not wild-type p53 specifically binds to MAR-DNA elements (MARs) with high affinity. Here we show that this DNA binding activity is exerted not only by MethA mutant p53 but also by other murine mutant p53 proteins isolated from the transformed murine BALB/c cell lines 3T3tx and T3T3 and differing in their conformational status. High affinity MAR-DNA binding was not restricted to the Xbal-IgE-MAR-DNA fragment from the murine immunoglobulin heavy chain gene enhancer locus [Cockerill et al. (1987): J Biol Chem 262:5394-5397] used in previous studies, as MethA p53 also specifically interacted with other A/T-rich bona fide MARs. Not only murine but also human mutant p53 proteins carrying the mutational hot spot amino acid exchanges 175Arg-->His, 273Arg-->Pro, or 273Arg-->His bound to the Xbal-IgE-MAR-DNA fragment. We therefore conclude that high affinity MAR-DNA binding is a property common to a variety of mutant p53 proteins.

Specific interaction of mutant p53 with regions of matrix attachment region DNA elements (MARs) with a high potential for base-unpairing

“…MAR binding by mut p53 so far had been demonstrated in a variety of different assays specifically adapted to measure the interaction of mut p53 with large DNA fragments, as represented by MARs (21)(22)(23). However, interactions of mut p53 with MARderived oligonucleotides could be analyzed best by EMSAs.…”

“…Murine and human mut p53, but not wt p53, specifically bind with high affinity to a variety of nuclear matrix attachment region DNA elements (MARs) (21)(22)(23). Due to the importance of MARs in nuclear processes such as gene expression and DNA replication, we hypothesized that this activity of mut p53 possibly could form the molecular basis for the documented oncogenic potential of mut p53 (4-7, 24, 25).…”

“…In this study we aimed at identifying unique sequence arrangements or distinct structural determinants on MARs that are specifically recognized by mut p53. MARs bound by mut p53 are quite different in size and sequence composition (23), but as a common feature, these MARs are AT-rich and contain variations of an AATATATTT ''unwinding'' motif, implicated in MAR function (26,27). Such motifs promote structural alterations within the chromatin, including regional base-unpairing (26,27).…”

Identification of genomic DNA sequences bound by mutant p53 protein (Gly245→Ser) in vivo

“…So far, the interaction of mut p53 with MAR DNA elements (MARs) has only been deduced from the ability of mut p53 to bind to a variety of such elements in vitro (Muller et al, 1996;Will et al, 1998a).…”

“…Although the MAR elements so far analysed for in vitro binding by mut p53 are characterized by a high AT-content, AT-richness as such is not su cient for mut p53 binding (Weissker et al, 1992;Will et al, 1998a). Furthermore, recent evidence suggested that the ability of sequence elements within MARs promoting the formation of a non-B DNA conformation is a critical feature for the recognition of MARs by mut p53 (Will et al, 1998b).…”