Disruption of а<i> fur-</i>Like Gene Inhibits Magnetosome Formation in <i>Magnetospirillum gryphiswaldense </i>MSR-1
Ferric uptake regulator (Fur) is a key factor in the regulation of iron-dependent gene expression. In this report, a genomic library <i>of Magnetospirillum gryphiswaldense </i>MSR-1 strain was constructed and a/иг-like gene was isolated and sequenced. This gene consisted of 420 bp and encoded 139 amino acid residues. To investigate the function of this gene in MSR-I, <i>a fur </i>mutant was generated by double crossover with a kanamycin cassette inserted into its coding region. Iron uptake and magnetosome formation were dramatically inhibited by disruption <i>of fur. </i>Iron content analysis of <i>the fur </i>mutant indicated that it contained approximately 0.037% by dry weight, which was at least 10-fold less than that observed in the wild type. Electron microscopy revealed the absence of a magnetosome in <i>the fur </i>mutant, although it was able to tolerate 1 mM H<sub>2</sub>0<sub>2</sub> at a 10-fold higher level than wild type. These data suggest that Fur may possess a novel function in magnetic bacteria.