ɛ‐Crystallin, a novel avian and reptilian eye lens protein

Stapel, S. O.; Zweers, Anneke; Dodemont, H.; Kan, Jaap H.; Jong, Wilfried W. de

doi:10.1111/j.1432-1033.1985.tb08728.x

Cited by 41 publications

(15 citation statements)

References 21 publications

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“…3). Because in the chicken lens no e-crystallin is detectable (12,13), the DNA of this species was used for comparison. From Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Approximately 250,000 plaques were obtained. The library was screened with antiserum against duck e-crystallin (13). To obtain longer cDNA clones, the library was subsequently rescreened with 32P-labeled 5' e-crystallin probes.…”

Section: Methodsmentioning

confidence: 99%

“…It is found in many bird and crocodile lenses at levels of up to 23% of total protein (12,13). Duck lens e-crystallin appeared to be almost indistinguishable, on the basis of partial amino acid sequence analysis, from duck heart lactate dehydrogenase (LDH) B4, and it displayed almost the full activity of this glycolytic enzyme (12).…”

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confidence: 99%

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Duck lens epsilon-crystallin and lactate dehydrogenase B4 are identical: a single-copy gene product with two distinct functions.

Hendriks

Mulders²,

Bibby³

et al. 1988

Proc. Natl. Acad. Sci. U.S.A.

109

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To investigate whether or not duck lens e-crystaliin and duck heart lactate dehydrogenase (LDH) B4are the product of the same gene, we have isolated and sequenced cDNA clones of duck e-crystallin. By using these clones we demonstrate that there is a single-copy Ldh-B gene in duck and in chicken. In the duck lens this gene is overexpressed, and its product is subject to posttranslational modification. Reconstruction of the evolutionary history of the LDH protein family reveals that the mammalian Ldh-C gene most probably originated from an ancestral Ldh-A gene and that the amino acid replacement rate in LDH-C is approximately 4 times the rate in LDH-A. Molecular modeling of LDH-B sequences shows that the increased thermostability of the avian tetramer might be explained by mutations that increase the number of ion pairs. Furthermore, the replacement of bulky side chains by glycines on the corners of the duck protein suggests an adaptation to facilitate close packing in the lens.

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“…3). Because in the chicken lens no e-crystallin is detectable (12,13), the DNA of this species was used for comparison. From Fig.…”

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Duck lens epsilon-crystallin and lactate dehydrogenase B4 are identical: a single-copy gene product with two distinct functions.

Hendriks

Mulders²,

Bibby³

et al. 1988

Proc. Natl. Acad. Sci. U.S.A.

109

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“…Furthermore, in the amino acid sequences of duck lens e-crystallin and LDH-B extracted from duck heart, the products of the same gene (16), two residues, Asn-114 and Phe-118, that are otherwise well conserved in LDH-A and -B subunits in vertebrates are replaced by glycine residues (8). In fact, the Phe/Gly-118 change is present in all of the other e-crystallin sequences previously examined (22). It has been hypothesized that these changes, presumably not beneficial to LDH enzymatic function, were selected for by the requirements of lens, producing flat patches on the surface of the LDH-B4 tetramer, perhaps involved in intermolecular interactions (5,16).…”

mentioning

confidence: 91%

“…e-Crystallin/LDH-B itself has some interesting features. It is found only in the lenses of many avian and crocodilian species (8,22), suggesting that it was recruited more recently than 6-crystallin/ ASL, in a common ancestor of the archosaurs. The fact that e-crystallin (as such) is not expressed in the lenses of all birds implies that its expression was lost again in some lines of descent.…”

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confidence: 99%

Evidence for neutral and selective processes in the recruitment of enzyme-crystallins in avian lenses.

Wistow

Anderson

Piatigorsky

1990

Proc. Natl. Acad. Sci. U.S.A.

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In apparent contrast to most other tissues, the ocular lenses in vertebrates show striking differences in protein composition between taxa, most notably in the recruitment of different enzymes as major structural proteins. This variability appears to be the result ofat least partially neutral evolutionary processes, although there is also evidence for selective modification in molecular structure. Here we describe a bird, the chimney swift (Chaetura pelagica), that lacks 8-crystallin/ argininosuccinate lyase, usually the major crystallin of avian lenses. Clearly, 6-crystallin is not specifically required for a functionally effective avian lens. Furthermore the lens composition of the swift is more similar to that of the related hummingbirds than to that of the barn swallow (Hirundo rustica), suggesting that phylogeny is more important than environmental selection in the recruitment of crystallins. However differences in e-crystallin/lactate dehydrogenase-B sequence between swift and hummingbird and other avian and reptilian species suggest that selective pressures may also be working at the molecular level. These differences also confirm the close relationship between swifts and hummingbirds.In many vertebrate species recruited enzymes comprise a large fraction of the crystallins, the soluble, structural proteins of the lens (1, 2). This phenomenon, a form of genesharing or protein multifunctionality, has wide implications for the processes of protein evolution and the mechanisms of differential gene expression. It also raises questions about the origins and roles of specific crystallins, why particular proteins were recruited as crystallins, and how important they are for correct lens development and function. Here we show that the expression of S-crystallin/argininosuccinate Iyase (ASL) (3) varies widely in avian lenses and appears to be more dependent on phylogeny than on any obvious functional or environmental selection. We have shown previously that two S-crystallin genes are abundantly expressed in the embryonic duck lens (refs. 4, 5; G.W. and J.P., unpublished data), whereas only one gene contributes significantly to 8-crystallin in the chicken lens (6, 7). Now we describe an avian species, the chimney swift (Chaetura pelagica), a fast-flying insectivore, that has no detectable lens expression of 8-crystallin at all, although its lens does contain abundant E-crystallin/lactate dehydrogenase B (LDH-B) (8). The hummingbirds are thought to be most closely related to the swifts in spite of marked superficial differences, most notably in feeding behavior. We have found that Anna's hummingbird (Calypte anna) does express detectable 8-crystallin but at a rather low level and also has extremely abundant e-crystallin. In contrast, the more distantly related barn swallow (Hirundo rustica), another fast-flying insectivore with similar feeding habits to the swift, has a quite different lens crystallin composition, with a more typical level of 6-crystallin and low or absent e-crystallin. Surprisingly, moreover...

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A Kinetic Analysis of the Endogenous Lactate Dehydrogenase Activity of Duck Lens ε-Crystallin in Reverse Micelles

Lee

Chang

1998

Journal of Colloid and Interface Science

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ɛ‐Crystallin, a novel avian and reptilian eye lens protein

Cited by 41 publications

References 21 publications

Duck lens epsilon-crystallin and lactate dehydrogenase B4 are identical: a single-copy gene product with two distinct functions.

Duck lens epsilon-crystallin and lactate dehydrogenase B4 are identical: a single-copy gene product with two distinct functions.

Evidence for neutral and selective processes in the recruitment of enzyme-crystallins in avian lenses.

A Kinetic Analysis of the Endogenous Lactate Dehydrogenase Activity of Duck Lens ε-Crystallin in Reverse Micelles

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