Regular Article
Characterization of γS-Crystallin Isoforms from Lip Shark (Chiloscyllium colax): Evolutionary Comparison between γS and β/γ Crystallins

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Abstract

γS-Crystallin from shark eye lenses, formerly termed βs crystallin in mammalian lenses, is structurally characterized in this study by cDNA cloning and sequencing. To facilitate sequence characterization of γS-crystallin possessing intermediate structural properties between β- and γ-crystallins, cDNA mixture was constructed from the poly(A)+mRNA isolated from shark eye lenses, and amplification by polymerase chain reaction (PCR) was carried out to obtain nucleotide segments encoding multiple shark γS-crystallins. Sequencing several positive clones revealed that a multiplicity of isoforms exists in the γS-crystallin class of this cartilaginous fish, similar to authentic γ-crystallin family characterized from the same shark species. Comparison of protein sequences encoded by two representative shark γS1 and γS2 cDNAs with those published sequences of β-, γ-, and γS crystallins from bovine, human, bullfrog and carp lenses indicated that there is about 35–64% sequence homology between shark γS crystallins and structurally related crystallins from different evolutionary classes, with a higher sequence similarity between shark γS and mammalian γ-crystallins than that of shark γS and carp γS or bovine γS crystallins. A phylogenetic tree constructed on the basis of the sequence divergence among various β-, γ-, and γS crystallins corroborates the closer relatedness of shark γS to authentic γ-crystallin than to mammalian and teleostean γS crystallins. It further strengthens the supposition that ancestral precursors of γS-crystallins were present in the shark lens long before the appearance of present-day teleostean and mammalian γS-crystallins.

References (28)

  • S.-H. Chiou

    FEBS Lett.

    (1986)
  • T. Chang et al.

    Biochim. Biophys. Acta

    (1988)
  • F.-M. Pan et al.

    Biochem. Biophys. Res. Commun.

    (1994)
  • G.L.M. van Rens et al.

    Gene

    (1989)
  • T. Chang et al.

    Biochim. Biophys. Acta

    (1987)
  • J. Hein

    Methods Enzymol.

    (1990)
  • R.J. Siezen et al.

    Exp. Eye Res.

    (1988)
  • S.-H. Chiou

    FEBS Lett.

    (1989)
  • S.-H. Chiou et al.

    FEBS Lett.

    (1990)
  • G. Wistow et al.

    J. Mol. Biol.

    (1983)
  • S.-F. Lu et al.

    Biochem. Biophys. Res. Commun.

    (1995)
  • F.-M. Pan et al.

    Biochem. Biophys. Res. Commun.

    (1995)
  • F.-M. Pan et al.

    Biochem. Biophys. Res. Commun.

    (1995)
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    The sequence data of cDNAs for shark γS-crystallins have been deposited in the EMBL Data Library under the Accession Numbers X79226 and X79227 for γS1 and γS2, respectively.

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    Corresponding address: Institute of Biochemical Sciences, National Taiwan University, P.O. Box 23-106, Taipei, Taiwan. Fax: (886)-2-3635038.

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