title: Regulation of MntH by a dual Mn(II)- and Fe(II)-dependent transcriptional repressor (DR2539) in Deinococcus radiodurans.
abstract: The high intracellular Mn/Fe ratio observed within the bacteria Deinococcus radiodurans may contribute to its remarkable resistance to environmental stresses. We isolated DR2539, a novel regulator of intracellular Mn/Fe homeostasis in D. radiodurans. Electrophoretic gel mobility shift assays (EMSAs) revealed that DR2539 binds specifically to the promoter of the manganese acquisition transporter (MntH) gene, and that DR0865, the only Fur homologue in D. radiodurans, cannot bind to the promoter of mntH, but it can bind to the promoter of another manganese acquisition transporter, MntABC. β-galactosidase expression analysis indicated that DR2539 acts as a manganese- and iron-dependent transcriptional repressor. Further sequence alignment analysis revealed that DR2539 has evolved some special characteristics. Site-directed mutagenesis suggested that His98 plays an important role in the activities of DR2539, and further protein-DNA binding activity assays showed that the activity of H98Y mutants decreased dramatically relative to wild type DR2539. Our study suggests that D. radiodurans has evolved a very efficient manganese regulation mechanism that involves its high intracellular Mn/Fe ratio and permits resistance to extreme conditions.
authors.affiliation: Key Laboratory for Nuclear-Agricultural Sciences of Chinese Ministry of Agriculture and Zhejiang Province, Institute of Nuclear-Agricultural Sciences, Zhejiang University, Hangzhou, China.
authors.forename: Hongxing
authors.initials: H
authors.lastname: Sun
authors.forename: Mingfeng
authors.initials: M
authors.lastname: Li
authors.forename: Guangzhi
authors.initials: G
authors.lastname: Xu
authors.forename: Huan
authors.initials: H
authors.lastname: Chen
authors.forename: Jiandong
authors.initials: J
authors.lastname: Jiao
authors.forename: Bing
authors.initials: B
authors.lastname: Tian
authors.forename: Liangyan
authors.initials: L
authors.lastname: Wang
authors.forename: Yuejin
authors.initials: Y
authors.lastname: Hua
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics*; D027682:Cation Transport Proteins / Q000096:biosynthesis / Q000235:genetics*; D034301:Deinococcus / Q000235:genetics / Q000378:metabolism*; D005296:Ferrous Compounds / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D008345:Manganese / Q000378:metabolism; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D012097:Repressor Proteins / Q000502:physiology*; D016415:Sequence Alignment
chemical_list: D001426:Bacterial Proteins; D027682:Cation Transport Proteins; D005296:Ferrous Compounds; C433793:MntH protein, bacteria; D012097:Repressor Proteins; D008345:Manganese