title: Identification of amino acid residues important for the function of Agrobacterium tumefaciens Irr protein.
abstract: The key amino acid residues that influence the function of the Agrobacterium tumefaciens iron response regulator protein (Irr(At) ) were investigated. Several Irr(At)  mutant proteins containing substitutions in amino acids corresponding to candidate metal- and haem-binding sites were constructed. The ability of the mutant proteins to repress the promoter of the membrane bound ferritin (mbfA) gene was investigated using a promoter-lacZ fusion assay. A single mutation at residue H94 significantly decreased the repressive activity of Irr(At) . Multiple mutation analysis revealed the importance of H45, H65, the HHH motif (H92, H93 and H94) and H127 for the repressor function of Irr(At) . H94 is essential for the iron responsiveness of Irr(At) . Furthermore, the Irr(At)  mutant proteins showed differential abilities to complement the H(2) O(2) -hyper-resistant phenotype of an irr mutant.
authors: Applied Biological Sciences, Chulabhorn Graduate Institute, Bangkok, Thailand.
authors: Sakkarin
authors: S
authors: Bhubhanil
authors: Nantaporn
authors: N
authors: Ruangkiattikul
authors: Phettree
authors: P
authors: Niamyim
authors: Jareeya
authors: J
authors: Chamsing
authors: Patchara
authors: P
authors: Ngok-Ngam
authors: Rojana
authors: R
authors: Sukchawalit
authors: Skorn
authors: S
authors: Mongkolsuk
mesh_terms: D016960:Agrobacterium tumefaciens / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D009154:Mutation; D014157:Transcription Factors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D014157:Transcription Factors; C114259:iron response regulator protein, Bacteria