1I5I

THE C18S MUTANT OF BOVINE (GAMMA-B)-CRYSTALLIN

Summary for 1I5I

• Entry DOI: 10.2210/pdb1i5i/pdb
• Related: 4gcr
• Descriptor: (GAMMA-B) CRYSTALLIN (2 entities in total)
• Functional Keywords: structural protein, eye lens protein, crystallin
• Biological source: Bos taurus (cattle)
• Total number of polymer chains: 1
• Total formula weight: 20976.49

Authors

Zarutskie, J.A.,Asherie, N.,Pande, J.,Pande, A.,Lomakin, J.,Lomakin, A.,Ogun, O.,Stern, L.J.,King, J.A.,Benedek, G.B. (deposition date: 2001-02-27, release date: 2001-03-07, Last modification date: 2023-08-09)

Primary citation

Asherie, N.,Pande, J.,Pande, A.,Zarutskie, J.A.,Lomakin, J.,Lomakin, A.,Ogun, O.,Stern, L.J.,King, J.,Benedek, G.B.
Enhanced crystallization of the Cys18 to Ser mutant of bovine gammaB crystallin.
J.Mol.Biol., 314:663-669, 2001

PubMed Abstract: The cysteine residues of the gamma crystallins, a family of ocular lens proteins, are involved in the aggregation and phase separation of these proteins. Both these phenomena are implicated in cataract formation. We have used bovine gammaB crystallin as a model system to study the role of the individual cysteine residues in the aggregation and phase separation of the gamma crystallins. Here, we compare the thermodynamic and kinetic behavior of the recombinant wild-type protein (WT) and the Cys18 to Ser (C18S) mutant. We find that the solubilities of the two proteins are similar. The kinetics of crystallization, however, are different. The WT crystallizes slowly enough for the metastable liquid-liquid coexistence to be easily observed. C18S, on the other hand, crystallizes rapidly; the metastable coexisting liquid phases of the pure mutant do not form. Nevertheless, the coexistence curve of C18S can be determined provided that crystallization is kinetically suppressed. In this way we found that the coexistence curve coincides with that of the WT. Despite the difference in the kinetics of crystallization, the two proteins were found to have the same crystal forms and almost identical X-ray structures. Our results demonstrate that even conservative point mutations can bring about dramatic changes in the kinetics of crystallization. The implications of our findings for cataract formation and protein crystallization are discussed.

PubMed: 11733987
DOI: 10.1006/jmbi.2001.5155

Experimental method

X-RAY DIFFRACTION (2.4 Å)