title: Positive regulation of fur gene expression via direct interaction of fur in a pathogenic bacterium, Vibrio vulnificus.
abstract: In pathogenic bacteria, the ability to acquire iron, which is mainly regulated by the ferric uptake regulator (Fur), is essential to maintain growth as well as its virulence. In Vibrio vulnificus, a human pathogen causing gastroenteritis and septicemia, fur gene expression is positively regulated by Fur when the iron concentration is limited (H.-J. Lee et al., J. Bacteriol. 185:5891-5896, 2003). Footprinting analysis revealed that an upstream region of the fur gene was protected by the Fur protein from DNase I under iron-depleted conditions. The protected region, from -142 to -106 relative to the transcription start site of the fur gene, contains distinct AT-rich repeats. Mutagenesis of this repeated sequence resulted in abolishment of binding by Fur. To confirm the role of this cis-acting element in Fur-mediated control of its own gene in vivo, fur expression was monitored in V. vulnificus strains using a transcriptional fusion containing the mutagenized Fur-binding site (fur(mt)::luxAB). Expression of fur(mt)::luxAB showed that it was not regulated by Fur and was not influenced by iron concentration. Therefore, this study demonstrates that V. vulnificus Fur acts as a positive regulator under iron-limited conditions by direct interaction with the fur upstream region.
authors.affiliation: Department of Parasitology, Yonsei University School of Medicine, 134 Shinchon-dong, Seodaemun-gu, Seoul 152-750, Republic of Korea.
authors.forename: Hyun-Jung
authors.initials: HJ
authors.lastname: Lee
authors.forename: So Hyun
authors.initials: SH
authors.lastname: Bang
authors.forename: Kyu-Ho
authors.initials: KH
authors.lastname: Lee
authors.forename: Soon-Jung
authors.initials: SJ
authors.lastname: Park
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D018983:DNA Footprinting; D017931:DNA Primers; D003850:Deoxyribonuclease I / Q000378:metabolism; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D007501:Iron / Q000378:metabolism; D007700:Kinetics; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010957:Plasmids; D011401:Promoter Regions, Genetic; D011994:Recombinant Proteins / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics* / Q000378:metabolism; D041261:Vibrio vulnificus / Q000235:genetics* / Q000472:pathogenicity
chemical_list: D001426:Bacterial Proteins; D017931:DNA Primers; D011994:Recombinant Proteins; D012097:Repressor Proteins; C068477:ferric uptake regulating proteins, bacterial; D007501:Iron; D003850:Deoxyribonuclease I