Redox-Dependent Dynamics in Heme-Bound Bacterial Iron Response Regulator (Irr) Protein

Biochemistry ◽  
2016 ◽  
Vol 55 (29) ◽  
pp. 4047-4054 ◽  
Author(s):  
Kazuo Kobayashi ◽  
Megumi Nakagaki ◽  
Haruto Ishikawa ◽  
Kazuhiro Iwai ◽  
Mark R. O’Brian ◽  
...  
Keyword(s):  
Response Regulator ◽  
Iron Response Regulator

scholarly journals Mechanistic insights into heme-mediated transcriptional regulation via a bacterial manganese-binding iron regulator, iron response regulator (Irr)

2020 ◽  
Vol 295 (32) ◽  
pp. 11316-11325
Author(s):  
Dayeon Nam ◽  
Yuki Matsumoto ◽  
Takeshi Uchida ◽  
Mark R. O'Brian ◽  
Koichiro Ishimori
Keyword(s):  
Binding Site ◽  
Fluorescence Anisotropy ◽  
Response Regulator ◽  
Binding Activity ◽  
Control Element ◽  
Heme Binding ◽  
Cluster Region ◽  
Ice Binding ◽  
Iron Response Regulator ◽  
Ice Complex

The transcription factor iron response regulator (Irr) is a key regulator of iron homeostasis in the nitrogen-fixating bacterium Bradyrhizobium japonicum. Irr acts by binding to target genes, including the iron control element (ICE), and is degraded in response to heme binding. Here, we examined this binding activity using fluorescence anisotropy with a 6-carboxyfluorescein-labeled ICE-like oligomer (FAM-ICE). In the presence of Mn2+, Irr addition increased the fluorescence anisotropy, corresponding to formation of the Irr–ICE complex. The addition of EDTA to the Irr–ICE complex reduced fluorescence anisotropy, but fluorescence was recovered after Mn2+ addition, indicating that Mn2+ binding is a prerequisite for complex formation. Binding activity toward ICE was lost upon introduction of substitutions in a His-cluster region of Irr, revealing that Mn2+ binds to this region. We observed that the His-cluster region is also the heme binding site; results from fluorescence anisotropy and electrophoretic mobility shift analyses disclosed that the addition of a half-equivalent of heme dissociates Irr from ICE, likely because of Mn2+ release due to heme binding. We hypothesized that heme binding to another heme binding site, Cys-29, would also inhibit the formation of the Irr–ICE complex because it is proximal to the ICE binding site, which was supported by the loss of ICE binding activity in a Cys-29–mutated Irr. These results indicate that Irr requires Mn2+ binding to form the Irr–ICE complex and that the addition of heme dissociates Irr from ICE by replacing Mn2+ with heme or by heme binding to Cys-29.

scholarly journals Protein oxidation mediated by heme-induced active site conversion specific for heme-regulated transcription factor, iron response regulator

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Chihiro Kitatsuji ◽  
Kozue Izumi ◽  
Shusuke Nambu ◽  
Masaki Kurogochi ◽  
Takeshi Uchida ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Protein Oxidation ◽  
Active Site ◽  
Response Regulator ◽  
Iron Response Regulator

scholarly journals Agrobacterium tumefaciens membrane-bound ferritin plays a role in protection against hydrogen peroxide toxicity and is negatively regulated by the iron response regulator

2012 ◽  
Vol 329 (1) ◽  
pp. 87-92 ◽  
Author(s):  
Nantaporn Ruangkiattikul ◽  
Sakkarin Bhubhanil ◽  
Jareeya Chamsing ◽  
Phettree Niamyim ◽  
Rojana Sukchawalit ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Agrobacterium Tumefaciens ◽  
Response Regulator ◽  
Membrane Bound ◽  
Iron Response Regulator

scholarly journals Unusual Heme Binding in the Bacterial Iron Response Regulator Protein: Spectral Characterization of Heme Binding to the Heme Regulatory Motif

Biochemistry ◽  
2011 ◽  
Vol 50 (6) ◽  
pp. 1016-1022 ◽  
Author(s):  
Haruto Ishikawa ◽  
Megumi Nakagaki ◽  
Ai Bamba ◽  
Takeshi Uchida ◽  
Hiroshi Hori ◽  
...  
Keyword(s):  
Response Regulator ◽  
Spectral Characterization ◽  
Heme Binding ◽  
Regulatory Motif ◽  
Regulator Protein ◽  
Iron Response Regulator ◽  
Response Regulator Protein

scholarly journals 2P062 Heme Binding Affinity of Iron Response Regulator (Irr) and its Regulation Mechanism

2004 ◽  
Vol 44 (supplement) ◽  
pp. S125
Author(s):  
M. Nakagaki ◽  
A. Bamba ◽  
H. Ishikawa ◽  
K. Iwai ◽  
Mark O'Brian ◽  
...  
Keyword(s):  
Binding Affinity ◽  
Response Regulator ◽  
Regulation Mechanism ◽  
Heme Binding ◽  
Iron Response Regulator

scholarly journals Identification of a Functional fur Gene in Bradyrhizobium japonicum

1999 ◽  
Vol 181 (18) ◽  
pp. 5843-5846 ◽  
Author(s):  
Iqbal Hamza ◽  
Richard Hassett ◽  
Mark R. O’Brian
Keyword(s):  
Escherichia Coli ◽  
Iron Metabolism ◽  
Bradyrhizobium Japonicum ◽  
Iron Uptake ◽  
Response Regulator ◽  
Functional Complementation ◽  
Global Regulator ◽  
Uptake Activity ◽  
Iron Response Regulator

ABSTRACT The recent identification of the iron response regulator (Irr) inBradyrhizobium japonicum raised the question of whether the global regulator Fur is present in that organism. A furgene homolog was isolated by the functional complementation of anEscherichia coli fur mutant. The B. japonicumFur bound to a Fur box DNA element in vitro, and a furmutant grown in iron-replete medium was derepressed for iron uptake activity. Thus, B. japonicum expresses at least two regulators of iron metabolism.

scholarly journals Iron Response Regulator Protein IrrB in Magnetospirillum gryphiswaldense MSR-1 Helps Control the Iron/Oxygen Balance, Oxidative Stress Tolerance, and Magnetosome Formation

2015 ◽  
Vol 81 (23) ◽  
pp. 8044-8053 ◽  
Author(s):  
Qing Wang ◽  
Meiwen Wang ◽  
Xu Wang ◽  
Guohua Guan ◽  
Ying Li ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Cell Growth ◽  
Iron Homeostasis ◽  
Response Regulator ◽  
Pcr Analysis ◽  
Oxygen Balance ◽  
Iron Storage ◽  
Magnetospirillum Gryphiswaldense ◽  
High Iron ◽  
Iron Response Regulator

ABSTRACTMagnetotactic bacteria are capable of forming nanosized, membrane-enclosed magnetosomes under iron-rich and oxygen-limited conditions. The complete genomic sequence ofMagnetospirillum gryphiswaldensestrain MSR-1 has been analyzed and found to contain fivefurhomologue genes whose protein products are predicted to be involved in iron homeostasis and the response to oxidative stress. Of these, only the MGMSRv2_3149 gene (irrB) was significantly downregulated under high-iron and low-oxygen conditions, during the transition of cell growth from the logarithmic to the stationary phase. The encoded protein, IrrB, containing the conserved HHH motif, was identified as an iron response regulator (Irr) protein belonging to the Fur superfamily. To investigate the function of IrrB, we constructed anirrBdeletion mutant (ΔirrB). The levels of cell growth and magnetosome formation were lower in the ΔirrBstrain than in the wild type (WT) under both high-iron and low-iron conditions. The ΔirrBstrain also showed lower levels of iron uptake and H2O2tolerance than the WT. Quantitative real-time reverse transcription-PCR analysis indicated that theirrBmutation reduced the expression of numerous genes involved in iron transport, iron storage, heme biosynthesis, and Fe-S cluster assembly. Transcription studies of the otherfurhomologue genes in the ΔirrBstrain indicated complementary functions of the Fur proteins in MSR-1. IrrB appears to be directly responsible for iron metabolism and homeostasis and to be indirectly involved in magnetosome formation. We propose two IrrB-regulated networks (under high- and low-iron conditions) in MSR-1 cells that control the balance of iron and oxygen metabolism and account for the coexistence of five Fur homologues.

scholarly journals 3P081 Heme Binding in Iron Response Regulator (Irr) and its Regulation Mechanism

2005 ◽  
Vol 45 (supplement) ◽  
pp. S224
Author(s):  
M. Nakagaki ◽  
T. Uchida ◽  
K. Kobayashi ◽  
H. Ishikawa ◽  
H. Kitagawa ◽  
...  
Keyword(s):  
Response Regulator ◽  
Regulation Mechanism ◽  
Heme Binding ◽  
Iron Response Regulator
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