Dataset Information

?-Crystallins of the chicken lens: remnants of an ancient vertebrate gene family in birds.

ABSTRACT: ?-Crystallins, abundant proteins of vertebrate lenses, were thought to be absent from birds. However, bird genomes contain well-conserved genes for ?S- and ?N-crystallins. Although expressed sequence tag analysis of chicken eye found no transcripts for these genes, RT-PCR detected spliced transcripts for both genes in chicken lens, with lower levels in cornea and retina/retinal pigment epithelium. The level of mRNA for ?S in chicken lens was relatively very low even though the chicken crygs gene promoter had lens-preferred activity similar to that of mouse. Chicken ?S was detected by a peptide antibody in lens, but not in other ocular tissues. Low levels of ?S and ?N proteins were detected in chicken lens by shotgun mass spectroscopy. Water-soluble and water-insoluble lens fractions were analyzed and 1934 proteins (< 1% false discovery rate) were detected, increasing the known chicken lens proteome 30-fold. Although chicken ?S is well conserved in protein sequence, it has one notable difference in leucine 16, replacing a surface glutamine conserved in other ?-crystallins, possibly affecting solubility. However, L16 and engineered Q16 versions were both highly soluble and had indistinguishable circular dichroism, tryptophan fluorescence and heat stability (melting temperature Tm ~ 65 °C) profiles. L16 has been present in birds for over 100 million years and may have been adopted for a specific protein interaction in the bird lens. However, evolution has clearly reduced or eliminated expression of ancestral ?-crystallins in bird lenses. The conservation of genes for ?S- and ?N-crystallins suggests they may have been preserved for reasons unrelated to the bulk properties of the lens.

SUBMITTER: Chen Y

PROVIDER: S-EPMC5576348 | biostudies-literature | 2016 Apr

REPOSITORIES: biostudies-literature

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γ-Crystallins of the chicken lens: remnants of an ancient vertebrate gene family in birds.

Chen Yingwei Y Sagar Vatsala V Len Hoay-Shuen HS Peterson Katherine K Fan Jianguo J Mishra Sanghamitra S McMurtry John J Wilmarth Phillip A PA David Larry L LL Wistow Graeme G

The FEBS journal 20160311 8

γ-Crystallins, abundant proteins of vertebrate lenses, were thought to be absent from birds. However, bird genomes contain well-conserved genes for γS- and γN-crystallins. Although expressed sequence tag analysis of chicken eye found no transcripts for these genes, RT-PCR detected spliced transcripts for both genes in chicken lens, with lower levels in cornea and retina/retinal pigment epithelium. The level of mRNA for γS in chicken lens was relatively very low even though the chicken crygs gene ...[more]

PMID: 26913478

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Dataset Information

?-Crystallins of the chicken lens: remnants of an ancient vertebrate gene family in birds.

Publications

γ-Crystallins of the chicken lens: remnants of an ancient vertebrate gene family in birds.

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