Characterization of the oligomerization defects of two p53 mutants found in families with Li–Fraumeni and Li–Fraumeni-like syndrome

Abstract

Recently two germline mutations in the oligomerization domain of p53 have been identi®ed in patients with Li ± Fraumeni and Li ± Fraumeni-like Syndromes. We have used biophysical and biochemical methods to characterize these two mutants in order to better understand their functional defects and the role of the p53 oligomerization domain (residues 325 ± 355) in oncogenesis. We ®nd that residues 310 ± 360 of the L344P mutant are monomeric, apparently unfolded and cannot interact with wild-type (WT) p53. The full length L344P protein is unable to bind sequence speci®cally to DNA and is therefore an inactive, but not a dominant negative mutant. R337C, on the other hand, can form dimers and tetramers, can hetero-oligomerize with WTp53 and can bind to a p53 consensus element. However, the thermal stability of R337C is much lower than that of WTp53 and at physiological temperatures more than half of this mutant is less than tetrameric. Thus, the R337C mutant retains some functional activity yet leads to a predisposition to cancer, suggesting that even partial inactivation of p53 oligomerization is su cient for accelerated tumour progression.

The p53 mutation “gradient effect” and its clinical implications

“…The R337C mutant improperly folds irrespective of pH and exhibits only partial biological activities (Davison et al, 1998). Consistent with this significant loss of functional activity, carriers of a germline R337C mutation are susceptible to multiple tumor types, including breast carcinoma (Lomax et al, 1998).…”

Unfolding, Aggregation, and Amyloid Formation by the Tetramerization Domain from Mutant p53 Associated with Lung Cancer

“…This process was found to be enhanced for the " hot-spot" R248Q contact and structural mutant, which is one of many changes in this domain known to destabilize the native structure (47). The other is for the R337H mutation in the tetramerization domain (48,49), which is associated with adrenocortical carcinoma (ACC) in children from southern Brazil (50). Both the WT and mutant peptides formed amyloid-like fibrils when incubated at pH 4.0 and elevated temperatures, with the mutant being susceptible at a lower temperature.…”

“…It should be noted, however, that in vivo the ability to form homo-or hetero-oligomers also may be modulated by the present of DNA binding sites and by the presence of several proteins that recently have been shown to specifically interact with the tetramerization domain. Mutant p53 with Arg337 changed to Cys, a change which is associated with Li-Fraumeni-like syndrome, also forms hetero-tetramers with wild-type p53; however, the hetero-tetramer retains some functional activity including DNA binding and an ability to activate transcription of some genes (49,59,60). However, the thermal stability of the R337C mutant is much lower than that of wild-type p53, and at physiological temperatures, less than half of this mutant is tetrameric.…”

ArhGAP30 promotes p53 acetylation and function in colorectal cancer

“…5f). However, the mutations that disrupted tetramerization (L344P) 46 or deleted the extreme C-terminal ARTICLE region of p53 (G374stop) were both able to abolish the p53-ArhGAP30 interaction (Fig. 5g).…”