Cloning, Expression, and Characterization of Cadmium and Manganese Uptake Genes from Lactobacillus plantarum

AUTOR(ES)
FONTE

American Society for Microbiology

RESUMO

An Mn2+ and Cd2+ uptake gene, mntA, was cloned from Lactobacillus plantarum ATCC 14917 into Escherichia coli. Its expression conferred on E. coli cells increased Cd2+ sensitivity as well as energy-dependent Cd2+ uptake activity. Both transcription and translation of mntA were induced by Mn2+ starvation in L. plantarum, as indicated by reverse transcriptase PCR and immunoblotting. Two Cd2+ uptake systems have been identified in L. plantarum: one is a high-affinity Mn2+ and Cd2+ uptake system that is expressed in Mn2+-starved cells, and the other is a nonsaturable Cd2+ uptake system that is expressed in Cd2+-sufficient cells (Z. Hao, H. R. Reiske, and D. B. Wilson, Appl. Environ. Microbiol. 65:592–99, 1999). MntA was not detected in an Mn2+-dependent mutant of L. plantarum which had lost high-affinity Mn2+ and Cd2+ uptake activity. The results suggest that mntA is the gene encoding the high-affinity Mn2+ and Cd2+ 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 Mn2+- and Cd2+-binding sites of MntA are discussed. A second clone containing a low-affinity Cd2+ transport system was also isolated.

ACESSO AO ARTIGO

Documentos Relacionados