Escherichia coli K-12 substr. MG1655 Enzyme: ferric reductase, NADPH-dependent

Gene: yqjH Accession Numbers: G7593 (EcoCyc), b3070, ECK3060

Regulation Summary Diagram: ?

Regulation summary diagram for yqjH

YqjH is an NADPH-dependent ferric reductase containing FAD, which is used as a cofactor rather than a substrate. The enzyme is only weakly active with purified ferric enterobactin [Wang11]; the hydrolyzed ferric enterobactin complex is the most efficient substrate [Miethke11].

Reports disagree on whether the FAD cofactor is covalently bound to a cysteine sidechain via a thioether bond [Wang11] or not covalently attached [Miethke11]. A preliminary report of crystallization and structure analysis of the YqjH protein has appeared. YqjH is structurally related to the NAD(P)H:flavin oxidoreductase superfamily [Bamford08]. The reaction mechanism of YqjH has been investigated in detail; a transient flavosemiquinone is involved in the single-electron transfer in a double-displacement-type reaction. The K55 and R130 residues are required for substrate binding and enzymatic activity. While the enzyme has high affinity for the intact ferric enterobactin, the catalytic turnover rate is much slower than for the hydrolyzed ferric triscatecholate [Miethke11].

The slow growth phenotype of a fes deletion mutant is enhanced by deletion of yqjH, supporting a role for YqjH in adaptation to iron starvation. Deletion of yqjH increases the toxicity of nickel [Wang11].

yqjH is part of the Fur regulon [McHugh03]; a candidate FUR box has been found upstream of the ORF [Panina01]. Expression of yqjH is repressed by both Fur and YqjI and is induced in response to nickel [Wang11].

Locations: cytosol

Map Position: [3,213,749 <- 3,214,513] (69.27 centisomes, 249°)
Length: 765 bp / 254 aa

Molecular Weight of Polypeptide: 28.872 kD (from nucleotide sequence)

Unification Links: ASAP:ABE-0010079 , EchoBASE:EB2787 , EcoGene:EG12953 , EcoliWiki:b3070 , ModBase:Q46871 , OU-Microarray:b3070 , PortEco:yqjH , Pride:Q46871 , Protein Model Portal:Q46871 , RefSeq:NP_417541 , RegulonDB:G7593 , SMR:Q46871 , String:511145.b3070 , UniProt:Q46871

Relationship Links: InterPro:IN-FAMILY:IPR007037 , InterPro:IN-FAMILY:IPR013113 , InterPro:IN-FAMILY:IPR017927 , InterPro:IN-FAMILY:IPR017938 , Pfam:IN-FAMILY:PF04954 , Pfam:IN-FAMILY:PF08021 , Prosite:IN-FAMILY:PS51384

Gene-Reaction Schematic: ?

Gene-Reaction Schematic

Genetic Regulation Schematic: ?

Genetic regulation schematic for yqjH

GO Terms:

Biological Process: GO:0033212 - iron assimilation Inferred from experiment [Miethke11]
GO:0071289 - cellular response to nickel ion Inferred from experiment [Wang11]
GO:0055114 - oxidation-reduction process Inferred by computational analysis [UniProtGOA11a, GOA01a]
Molecular Function: GO:0050660 - flavin adenine dinucleotide binding Inferred from experiment [Bamford08]
GO:0052851 - ferric-chelate reductase (NADPH) activity Inferred from experiment Inferred by computational analysis [GOA01, Wang11]
GO:0071949 - FAD binding Inferred from experiment [Miethke11]
GO:0016491 - oxidoreductase activity Inferred by computational analysis [UniProtGOA11a, GOA01a]
Cellular Component: GO:0005829 - cytosol Inferred from experiment Inferred by computational analysis [DiazMejia09, Ishihama08]
GO:0005737 - cytoplasm Inferred by computational analysis [UniProtGOA11, UniProtGOA11a]

MultiFun Terms: cell processes adaptations Fe aquisition

Essentiality data for yqjH knockouts: ?

Growth Medium Growth? T (°C) O2 pH Osm/L Growth Observations
LB enriched Yes 37 Aerobic 6.95   Yes [Gerdes03, Comment 1]
LB Lennox Yes 37 Aerobic 7   Yes [Baba06, Comment 2]
M9 medium with 1% glycerol Yes 37 Aerobic 7.2 0.35 Yes [Joyce06, Comment 3]
MOPS medium with 0.4% glucose Yes 37 Aerobic 7.2 0.22 Yes [Baba06, Comment 2]

Last-Curated ? 30-Nov-2011 by Keseler I , SRI International

Enzymatic reaction of: ferric reductase

EC Number:

2 Fe2+ + 2 (2,3-dihydroxybenzoylserine)3 + NADP+ <=> 2 ferric (2,3-dihydroxybenzoylserine)3 + NADPH + 9 H+

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the Enzyme Commission system.

The reaction is physiologically favored in the opposite direction.

Alternative Substrates for ferric (2,3-dihydroxybenzoylserine)3: ferric enterobactin complex [Miethke11 ] , ferric dicitrate [Miethke11 ]

The enzyme is most active with the hydrolyzed ferric triscatecholate complex, but is able to utilize intact ferric triscatecholates and ferric dicitrate with lower catalytic efficiency [Miethke11].

Kinetic Parameters:

Km (μM)
ferric enterobactin complex
ferric dicitrate
ferric (2,3-dihydroxybenzoylserine)3

Enzymatic reaction of: ferric reductase

EC Number:

2 Fe2+ + 2 a siderophore + NADP+ + H+ <=> 2 an Fe(III)-siderophore + NADPH

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the Enzyme Commission system.

The reaction is physiologically favored in the opposite direction.

The enzyme is specific for NADPH [Wang11].

Kinetic Parameters:

Km (μM)

Sequence Features

Protein sequence of ferric reductase, NADPH-dependent with features indicated

Feature Class Location Citations Comment
Conserved-Region 15 -> 136
UniProt: FAD-binding FR-type;

Gene Local Context (not to scale): ?

Gene local context diagram

Transcription Unit:

Transcription-unit diagram


Markus Krummenacker on Tue Oct 14, 1997:
Gene object created from Blattner lab Genbank (v. M52) entry.


Baba06: Baba T, Ara T, Hasegawa M, Takai Y, Okumura Y, Baba M, Datsenko KA, Tomita M, Wanner BL, Mori H (2006). "Construction of Escherichia coli K-12 in-frame, single-gene knockout mutants: the Keio collection." Mol Syst Biol 2;2006.0008. PMID: 16738554

Bamford08: Bamford VA, Armour M, Mitchell SA, Cartron M, Andrews SC, Watson KA (2008). "Preliminary X-ray diffraction analysis of YqjH from Escherichia coli: a putative cytoplasmic ferri-siderophore reductase." Acta Crystallogr Sect F Struct Biol Cryst Commun 64(Pt 9);792-6. PMID: 18765906

DiazMejia09: Diaz-Mejia JJ, Babu M, Emili A (2009). "Computational and experimental approaches to chart the Escherichia coli cell-envelope-associated proteome and interactome." FEMS Microbiol Rev 33(1);66-97. PMID: 19054114

Gerdes03: Gerdes SY, Scholle MD, Campbell JW, Balazsi G, Ravasz E, Daugherty MD, Somera AL, Kyrpides NC, Anderson I, Gelfand MS, Bhattacharya A, Kapatral V, D'Souza M, Baev MV, Grechkin Y, Mseeh F, Fonstein MY, Overbeek R, Barabasi AL, Oltvai ZN, Osterman AL (2003). "Experimental determination and system level analysis of essential genes in Escherichia coli MG1655." J Bacteriol 185(19);5673-84. PMID: 13129938

GOA01: GOA, MGI (2001). "Gene Ontology annotation based on Enzyme Commission mapping." Genomics 74;121-128.

GOA01a: GOA, DDB, FB, MGI, ZFIN (2001). "Gene Ontology annotation through association of InterPro records with GO terms."

Ishihama08: Ishihama Y, Schmidt T, Rappsilber J, Mann M, Hartl FU, Kerner MJ, Frishman D (2008). "Protein abundance profiling of the Escherichia coli cytosol." BMC Genomics 9;102. PMID: 18304323

Joyce06: Joyce AR, Reed JL, White A, Edwards R, Osterman A, Baba T, Mori H, Lesely SA, Palsson BO, Agarwalla S (2006). "Experimental and computational assessment of conditionally essential genes in Escherichia coli." J Bacteriol 188(23);8259-71. PMID: 17012394

McHugh03: McHugh JP, Rodriguez-Quinones F, Abdul-Tehrani H, Svistunenko DA, Poole RK, Cooper CE, Andrews SC (2003). "Global iron-dependent gene regulation in Escherichia coli. A new mechanism for iron homeostasis." J Biol Chem 278(32);29478-86. PMID: 12746439

Miethke11: Miethke M, Hou J, Marahiel MA (2011). "The siderophore-interacting protein YqjH acts as a ferric reductase in different iron assimilation pathways of Escherichia coli." Biochemistry 50(50);10951-64. PMID: 22098718

Panina01: Panina EM, Mironov AA, Gelfand MS (2001). "Comparative analysis of FUR regulons in gamma-proteobacteria." Nucleic Acids Res 29(24);5195-206. PMID: 11812853

UniProt09: UniProt Consortium (2009). "UniProt version 15.8 released on 2009-10-01 00:00:00." Database.

UniProtGOA11: UniProt-GOA (2011). "Gene Ontology annotation based on the manual assignment of UniProtKB Subcellular Location terms in UniProtKB/Swiss-Prot entries."

UniProtGOA11a: UniProt-GOA (2011). "Gene Ontology annotation based on manual assignment of UniProtKB keywords in UniProtKB/Swiss-Prot entries."

Wang11: Wang S, Wu Y, Outten FW (2011). "Fur and the novel regulator YqjI control transcription of the ferric reductase gene yqjH in E. coli." J Bacteriol 193(2):563-74. PMID: 21097627

Other References Related to Gene Regulation

Chen07: Chen Z, Lewis KA, Shultzaberger RK, Lyakhov IG, Zheng M, Doan B, Storz G, Schneider TD (2007). "Discovery of Fur binding site clusters in Escherichia coli by information theory models." Nucleic Acids Res 35(20);6762-77. PMID: 17921503

Lavrrar03: Lavrrar JL, McIntosh MA (2003). "Architecture of a fur binding site: a comparative analysis." J Bacteriol 185(7);2194-202. PMID: 12644489

Wang14a: Wang S, Blahut M, Wu Y, Philipkosky KE, Outten FW (2014). "Communication between binding sites is required for YqjI regulation of target promoters within the yqjH-yqjI intergenic region." J Bacteriol 196(17);3199-207. PMID: 24982304

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Please cite the following article in publications resulting from the use of EcoCyc: Nucleic Acids Research 41:D605-12 2013
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