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Calcium Binding Dramatically Stabilizes an Ancestral Crystallin Fold in Tunicate βγ-Crystallin.

ABSTRACT: The tunicate (Ciona intestinalis) βγ-crystallin represents an intermediate case between the calcium-binding proteins ancestral to the vertebrate βγ-crystallin fold and the vertebrate structural crystallins. Unlike the structural βγ-crystallins in the vertebrate eye lens, this βγ-crystallin strongly binds Ca²⁺. Furthermore, Ca²⁺ binding greatly stabilizes the protein, an effect that has previously been observed in microbial βγ-crystallins but not in those of vertebrates. This relationship between binding and protein stabilization makes the tunicate βγ-crystallin an interesting model for studying the evolution of the human βγ-crystallin. We also compare and contrast the binding sites of tunicate βγ-crystallin with those of other βγ-crystallins to develop hypotheses about the functional origin of the lack of Ca²⁺-binding sites in human crystallins.

SUBMITTER: Kozlyuk N

PROVIDER: S-EPMC6936725 | biostudies-literature | 2016 Dec

REPOSITORIES: biostudies-literature

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Calcium Binding Dramatically Stabilizes an Ancestral Crystallin Fold in Tunicate βγ-Crystallin.

Kozlyuk Natalia N Sengupta Suvrajit S Bierma Jan C JC Martin Rachel W RW

Biochemistry 20161208 50

The tunicate (Ciona intestinalis) βγ-crystallin represents an intermediate case between the calcium-binding proteins ancestral to the vertebrate βγ-crystallin fold and the vertebrate structural crystallins. Unlike the structural βγ-crystallins in the vertebrate eye lens, this βγ-crystallin strongly binds Ca2+. Furthermore, Ca2+ binding greatly stabilizes the protein, an effect that has previously been observed in microbial βγ-crystallins but not in those of vertebrates. Thi ...[more]

PMID: 27992995

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