Cloning, expression, and characterization of cadmium and manganese uptake genes from Lactobacillus plantarum.
An Mn(2+) and Cd(2+) uptake gene, mntA, was cloned from Lactobacillus plantarum ATCC 14917 into Escherichia coli. Its expression conferred on E. coli cells increased Cd(2+) sensitivity as well as energy-dependent Cd(2+) uptake activity. Both transcription and translation of mntA were induced by Mn(2+) starvation in L. plantarum, as indicated by reverse transcriptase PCR and immunoblotting. Two Cd(2+) uptake systems have been identified in L. plantarum: one is a high-affinity Mn(2+) and Cd(2+) uptake system that is expressed in Mn(2+)-starved cells, and the other is a nonsaturable Cd(2+) uptake system that is expressed in Cd(2+)-sufficient cells (Z. Hao, H. R. Reiske, and D. B. Wilson, Appl. Environ. Microbiol. 65:592-99, 1999). MntA was not detected in an Mn(2+)-dependent mutant of L. plantarum which had lost high-affinity Mn(2+) and Cd(2+) uptake activity. The results suggest that mntA is the gene encoding the high-affinity Mn(2+) and Cd(2+) transporter. On the basis of its predicted amino acid sequence, MntA belongs to the family of P-type cation-translocating ATPases. The topology and potential Mn(2+)- and Cd(2+)-binding sites of MntA are discussed. A second clone containing a low-affinity Cd(2+) transport system was also isolated.
Hao
Z
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Institute for Comparative and Environmental Toxicology, Cornell University, Ithaca, New York 14853, USA.
Chen
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S
Wilson
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D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins; D001692:Biological Transport / Q000235:genetics; D002104:Cadmium / Q000378:metabolism*; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D027682:Cation Transport Proteins; D017124:Conserved Sequence; D005798:Genes, Bacterial; D015698:Genomic Library; D006801:Humans; D007700:Kinetics; D007778:Lactobacillus / Q000235:genetics* / Q000378:metabolism*; D008345:Manganese / Q000378:metabolism*; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D017433:Protein Structure, Secondary; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
D001426:Bacterial Proteins; D002352:Carrier Proteins; D027682:Cation Transport Proteins; D012333:RNA, Messenger; D011994:Recombinant Proteins; C400921:mntA protein, Lactobacillus plantarum; D002104:Cadmium; D008345:Manganese