Mutation of alpha B-crystallin: effects on chaperone-like activity.
A recent paper by Plater et al. [20], showed that the mutation of a single phenylalanine residue F27R in mouse alpha B completely abolished the chaperone-like property of alpha-crystallin when assayed with insulin 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 human alpha B-crystallin. Our data suggest that the F27R mutation effected the thermal stability of alpha B-crystallin making it unstable at temperatures > or = 60 degrees C. In agreement with the published work, at these temperatures the F27R human recombinant alpha 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-crystallin. Several other multiple mutations involving proline residues were also produced. These mutations did not effect the chaperone-like properties of human alpha B-crystallin, but some of them did effect the native molecular weight size as judged by gel filtration chromatography.
Horwitz
J
J
Jules Stein Eye Institute, UCLA School of Medicine 90095-7008, USA. Horwitz@jsei.ucla.edu
Bova
M
M
Huang
Q L
QL
Ding
L
L
Yaron
O
O
Lowman
S
S
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D002417:Cattle; D002942:Circular Dichroism; D003459:Crystallins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D017931:DNA Primers / Q000235:genetics; D004355:Drug Stability; D006801:Humans; D066298:In Vitro Techniques; D007768:Lactalbumin / Q000737:chemistry / Q000378:metabolism; D051379:Mice; D018832:Molecular Chaperones / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D008970:Molecular Weight; D016297:Mutagenesis, Site-Directed; D017354:Point Mutation; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013696:Temperature
D003459:Crystallins; D017931:DNA Primers; D018832:Molecular Chaperones; D011994:Recombinant Proteins; D007768:Lactalbumin