MUTATION OF ALPHA-B-CRYSTALLIN - EFFECTS ON CHAPERONE-LIKE ACTIVITY

A recent paper by Plater et al. [20], showed that the mutation of a si ngle phenylalanine residue F27R in mouse alpha B completely abolished the chaperone-like property of alpha-crystallin when assayed with insu lin at 25 degrees C or with gamma-crystallin at 66 degrees C. We have produced the same mutation as well as some additional mutations in hum an alpha B-crystallin. Our data suggest that the F27R mutation effecte d the thermal stability of alpha B-crystallin making it unstable at te mperatures greater than or equal to 60 degrees C. In agreement with th e published work, at these temperatures the F27R human recombinant alp ha B-crystallin does not protect the target protein from aggregation. When assayed with insulin or alpha-lactalbumin at 25 or 37 degrees C, however, there were no differences in the protective abilities between the native alpha B-crystallin or the F27R mutated human alpha B-cryst allin. Several other multiple mutations involving proline residues wer e also produced. These mutations did not effect the chaperone-like pro perties of human alpha B-crystallin, but some of them did effect the n ative molecular weight size as judged by gel filtration chromatography . (C) 1998 Elsevier Science B.V. All rights reserved.