Lambda-crystallin, a major rabbit lens protein, is related to hydroxyacyl-coenzyme A dehydrogenases.
It has recently been discovered that several lens proteins in birds and lower vertebrates are active enzymes or enzyme-related proteins (Wistow, G., Mulders, J. W. M., and de Jong, W. W. (1987) Nature 326, 622-624; Wistow, G., and Piatigorsky, J. (1987) Science 236, 1554-1556). We report here a novel lens protein, designated as lambda-crystallin, that occurs in rabbit and hare. It constitutes 7-8% of the total lens protein and has a subunit molecular mass of 35 kDa. Sequencing of cDNA clones encoding rabbit lambda-crystallin revealed 30% homology (at the amino acid sequence level) with L-3-hydroxyacyl-CoA dehydrogenase from pig mitochondria and 26% homology with enoyl-CoA hydratase-3-hydroxyacyl-CoA dehydrogenase from rat peroxisomes. Also, the presence of a putative beta-alpha-beta nucleotide-binding fold and low levels of non-lens expression are indicative of some enzymatic function for lambda-crystallin (or highly related sequences) in non-lens tissues. lambda-Crystallin thus represents the first example of an enzyme-related crystallin in lenses from mammalian species. The recruitment of enzymes as lens structural proteins apparently is an evolutionary strategy which has been applied independently in different lineages.
Mulders
J W
JW
Department of Biochemistry, University of Nijmegen, The Netherlands.
Hendriks
W
W
Blankesteijn
W M
WM
Bloemendal
H
H
de Jong
W W
WW
D015094:3-Hydroxyacyl CoA Dehydrogenases / Q000032:analysis*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D003459:Crystallins / Q000032:analysis*; D004247:DNA / Q000032:analysis; D008969:Molecular Sequence Data; D008970:Molecular Weight; D011817:Rabbits
D003459:Crystallins; D004247:DNA; D015094:3-Hydroxyacyl CoA Dehydrogenases