Lactate Dehydrogenase Like Crystallin: A Potentially Protective Shield for Indian Spiny-Tailed Lizard (Uromastyx hardwickii) Lens Against Environmental Stress?
Taxon specific lens crystallins in vertebrates are either similar or identical with various metabolic enzymes. These bifunctional crystallins serve as structural protein in lens along with their catalytic role. In the present study, we have partially purified and characterized lens crystallin from Indian spiny-tailed lizard (Uromastyx hardwickii). We have found lactate dehydrogenase (LDH) activity in lens indicating presence of an enzyme crystallin with dual functions. Taxon specific lens crystallins are product of gene sharing or gene duplication phenomenon where a pre-existing enzyme is recruited as lens crystallin in addition to structural role. In lens, same gene adopts refractive role in lens without modification or loss of pre-existing function during gene sharing phenomenon. Apart from conventional role of structural protein, LDH activity containing crystallin in U. hardwickii lens is likely to have adaptive characteristics to offer protection against toxic effects of oxidative stress and ultraviolet light, hence justifying its recruitment. Taxon specific crystallins may serve as good models to understand structure–function relationship of these proteins.
Keywordsε-Crystallin Gene recruitment Gene sharing Lactate dehydrogenase Reptilian lens Taxon specific crystallin
Reverse phase-high performance liquid chromatography
DNA sequencing analysis and N-terminal protein sequencing were provided by Centralized Science Laboratory, University of Karachi, Pakistan and RI-INBRE Centralized Core Facility, University of Rhode Island, USA, supported by Grant # 5P20GM103430-13 from the National Institute of General Medical Sciences of the National Institute of Health.
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