An Iron-regulated Gene, magA, Encoding an Iron Transport Protein of Magnetospirillum sp. Strain AMB-1

• Published in: The Journal of biological chemistry 1995-11, Vol.270 (47), p.28392-28396
• Main Authors: Nakamura, C, Burgess, J G, Sode, K, Matsunaga, T
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Bacteria - genetics; Bacteria - isolation & purification; Bacteria - metabolism; Bacterial Proteins - chemistry; Base Sequence; Blotting, Northern; Carrier Proteins - biosynthesis; Carrier Proteins - chemistry; Carrier Proteins - genetics; Carrier Proteins - metabolism; Cation Transport Proteins; Cloning, Molecular; DNA Transposable Elements; Enterococcus hirae; Escherichia coli; Escherichia coli Proteins; Gene Expression Regulation, Bacterial - drug effects; Iron - metabolism; Iron - pharmacology; Kinetics; Magnetics; Magnetospirillum; Molecular Sequence Data; Mutagenesis, Insertional; Open Reading Frames; Potassium Channels; Recombinant Proteins - biosynthesis; Recombinant Proteins - chemistry; Restriction Mapping; RNA, Messenger - analysis; RNA, Messenger - biosynthesis; Sequence Homology, Amino Acid
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.270.47.28392

Magnetospirillum sp. AMB-1 is a freshwater magnetic bacterium which synthesizes intracellular particles of magnetite (Fe O ). A genomic DNA fragment required for synthesis of magnetic particles was previously isolated from a nonmagnetic transposon Tn 5 mutant. We have determined the complete nucleotide sequence of this fragment. The 2975-base pair region contains two putative open reading frames. One open reading frame, designated magA , encodes a polypeptide which is homologous to the cation efflux proteins, the Escherichia coli potassium ion-translocating protein, KefC, and the putative Na /H -antiporter, NapA, from Enterococcus hirae . Northern hybridization demonstrated that the magA mRNA transcript is 1.3 kilobases in size, corresponding to the size of the magA gene. A functional promoter was located upstream from the magA gene, and the transcription in AMB-1 was regulated by environmental iron concentration. Vesicles isolated from E. coli in which the MagA protein was expressed exhibited iron accumulation ability. We consider that the MagA protein is an iron transport involved in the synthesis of magnetic particles in AMB-1.