The roles of iron in the growth and physiology of the marine alga Dunaliella tertiolecta were investigated. Comparison of the electrophoretic profiles of total proteins from cells grown under iron-replete or iron-deficient conditions revealed that the abundance of a 38-kDa protein
was markedly increased in cells deprived of iron. Electron microscopy also revealed that cells subjected to iron limitation exhibited substantial chlorosis and a defective photosynthetic apparatus. In addition, immunoblot analysis showed that iron deprivation increased the abundance of a 150-kDa
protein that reacts with antibodies to human transferrin. With the use of the polymerase chain reaction and primers based on the nucleotide sequences of a gene for a transferrin-like protein in Dunaliella salina, a 9.5-kb fragment of D. tertiolecta genomic DNA that encodes a
homologous protein was isolated and sequenced. The fragment isolated from D. tertiolecta comprises 30 exons and contains an open reading frame of 3825 bp that encodes a protein of 1274 amino acids. The predicted amino acid sequence of the encoded protein shows a high degree of homology
to those of various transferring proteins from other organisms.
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