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Cloning, Sequencing, Characterization, and Expressions of Divalent Metal Transporter One in the Small Intestine of Broilers¹

S. P. Bai^*,, L. Lu^*,, X. G. Luo^*,,2 and B. Liu^*,

^* Mineral Nutrition Research Division, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing 100094, P. R. China; and State Key Laboratory of Animal Nutrition, Beijing 100094, P. R. China

² Corresponding author: wlysz{at}263.net

Divalent metal transporter 1 (DMT1) is an electrogenic transporter of divalent Mn that is expressed at a high level on the brush-border membrane of enterocytes. This study is the first reported isolation of the 2 full-length cDNA sequences of the small intestinal DMT1 gene of broilers by rapid amplification of cDNA ends. The chicken DMT1 isoform I cDNA was 1,972 bp and contained a 1,695-bp open reading frame encoding a 564-amino acid protein, and the chicken DMT1 isoform II cDNA was 1,775 bp and contained a 1,593-bp open reading frame encoding a 530-amino acid protein. The 2 chicken DMT1 isoform transcripts differed in their 3'-translated regions and untranslated regions. The identities of the amino acid sequence deduced from the full-length cDNA sequence of the chicken DMT1 isoform I with DMT1 not containing the iron-responsive element of the mouse, rat, and human were 82, 82, and 80%, respectively. The identities of the amino acid sequence deduced from the full-length cDNA sequence of the chicken DMT1 isoform II with those of the mouse, rat, and human were 84, 84, and 83%, respectively. Analyses of hydrophobicity, transmembrane region, and signal peptides of DMT1 proteins deduced by nucleotide sequences suggested that chicken DMT1 isoforms are transmembrane proteins with several conserved peptide sequences, such as N-linked glycosylation signals (N-X-S/ T, where X designates any amino acid) and the consensus transport motif. The total mRNA levels of the 2 chicken DMT1 isoforms, the mRNA levels of chicken DMT1 isoform I, and the mRNA levels of chicken DMT1 isoform II in the duodenum and jejunum were higher (P < 0.002) than that in the ileum by real-time reverse transcription PCR assay. There was no significant difference (P > 0.26) between the duodenum and jejunum for the above 3 indices. The mRNA level of the chicken DMT1 isoform I was higher (P < 0.001) than that of the chicken DMT1 isoform II in each small intestinal segment of Mn-deficient broilers.

Key Words: divalent metal transporter 1 • nucleotide sequence • mRNA level • small intestine • broiler

¹ Supported by the National Basic Research Program of China (project no. 2004, CB117501; Beijing, China), the Key Program of the National Natural Science Foundation of China (project no. 30530570; Beijing, China), and Chinese Academy of Agricultural Sciences Foundation for First-Place Outstanding Scientists (Chinese Academy of Agricultural Sciences, Beijing, China).