Purchase this article with an account.
C. Yang, J.F. Koretz; The Structural and Functional Role of the Region Bridging the N-Terminal and Central Core of Alpha-Crystallin . Invest. Ophthalmol. Vis. Sci. 2003;44(13):2138.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Purpose: The N-terminal region of alphaA- or alphaB-crystallin can be deleted, as shown by this laboratory and by Feil et al. (2001) without loss of the remaining sequence's ability to fold into a compact, soluble structure or to exhibit chaperone-like activity. There is some disagreement, however, as to the impact of N-terminal removal on the level of function remaining. To characterize the boundary between the N-terminal and central core of alphaA-crystallin, a series of deletion mutants have been designed and expressed. Methods: The alphaA-crystallin homology model of Salerno, Salerno, Eifert, and Koretz (in press) was used as the basis for selection of deletion points. In addition to the original mutant with a sequence beginning at residue 51, other mutants with sequences beginning at residues 55, 59, and 60 were produced. These mutants were characterized structurally using gel filtration chromatography and far-UV CD spectroscopy, and functionally using the insulin denaturation assay. Results: All four mutant species appear to fold similarly, as determined from comparison of their CD spectra. The soluble aggregates generated by them all show a molecular weight by gel filtration chromatography consistent with a tetramer, although broadening of the elution peak suggests a tetramer-dimer equilibrium. Chaperone-like activity, however, is close to nil for all the mutants except for the original one beginning at residue 51. Conclusion: The amino acid sequence bridging the N-terminal and central core regions of alphaA-crystallin does not seem to be essential for proper protein folding or assembly into soluble aggregates. One or more of the residues in the region between 51 and 55, however, appear to be critical for chaperone-like activity.
This PDF is available to Subscribers Only