Escherichia coli K-12 substr. MG1655 Transporter: guanine / hypoxanthine transporter GhxQ

Gene: ghxQ Accession Numbers: G7503 (EcoCyc), b4464, ECK2880

Synonyms: b2885 (obsolete), ygfR, b2884 (obsolete), ygfQ

Regulation Summary Diagram: ?

Regulation summary diagram for ghxQ

Cloned and overexpressed GhxQ transports labelled guanine and hypoxanthine, but not adenine, xanthine, uric acid or uracil in E. coli K-12 [Papakostas13]. GhxQ is a member of the nucleobase:cation symporter 2 (NCS2) family of transporters [Saier09].

GhxQ has been predicted to be a xanthine, uracil permease by bioinformatic analysis [Xi00]. Expression of ghxQ was induced at acidic pH [Tucker02] and increased after puromycin challenge of a relA strain [Sabina03]. Expression of a genomic library clone containing ghxQ and fragments of its flanking genes resulted in reduced expression of a rybB-LacZ fusion [Thompson07].

ghxQ: guanine / hypoxanthine permease Q

Locations: inner membrane

Map Position: [3,025,143 -> 3,026,510] (65.2 centisomes, 235°)
Length: 1368 bp / 455 aa

Molecular Weight of Polypeptide: 46.758 kD (from nucleotide sequence)

Unification Links: ASAP:ABE-0174113 , EchoBASE:EB2879 , EcoGene:EG13067 , EcoliWiki:b4464 , OU-Microarray:b2884 , PortEco:ygfQ , Protein Model Portal:Q46817 , RefSeq:YP_026186 , RegulonDB:G7503 , String:511145.b4464 , UniProt:Q46817

Relationship Links: EcoO157Cyc:Homolog:Z4223 , EcoO157Cyc:Homolog:Z4223-MONOMER , EcoO157Cyc:Homolog:Z5153-MONOMER , InterPro:IN-FAMILY:IPR006043 , InterPro:IN-FAMILY:IPR029940 , Panther:IN-FAMILY:PTHR11119 , Panther:IN-FAMILY:PTHR11119:SF9 , Pfam:IN-FAMILY:PF00860 , Prosite:IN-FAMILY:PS01116

In Paralogous Gene Group: 467 (3 members)

Gene-Reaction Schematic: ?

Gene-Reaction Schematic

GO Terms:

Biological Process: GO:0035344 - hypoxanthine transport Inferred from experiment [Papakostas13]
GO:0061489 - guanine import into cell Inferred from experiment [Papakostas13]
GO:1903716 - guanine transmembrane transport Inferred from experiment [Papakostas13]
GO:0006810 - transport Inferred by computational analysis [UniProtGOA11a, Xi00]
GO:0006863 - purine nucleobase transport Inferred by computational analysis [GOA01a]
GO:0055085 - transmembrane transport Inferred by computational analysis [GOA01a]
Molecular Function: GO:0015208 - guanine transmembrane transporter activity Inferred from experiment [Papakostas13]
GO:0005215 - transporter activity Inferred by computational analysis [GOA01a, Xi00]
GO:0005345 - purine nucleobase transmembrane transporter activity Inferred by computational analysis [GOA01a]
Cellular Component: GO:0005886 - plasma membrane Inferred from experiment Inferred by computational analysis [UniProtGOA11, UniProtGOA11a, DiazMejia09, Daley05]
GO:0005887 - integral component of plasma membrane Inferred by computational analysis [Daley05]
GO:0016020 - membrane Inferred by computational analysis [UniProtGOA11a, GOA01a]
GO:0016021 - integral component of membrane Inferred by computational analysis [UniProtGOA11a]

MultiFun Terms: transport Electrochemical potential driven transporters Porters (Uni-, Sym- and Antiporters)

Essentiality data for ghxQ 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]

Curated 13-May-2008 by Johnson A , JCVI
Last-Curated ? 11-Dec-2013 by Mackie A , Macquarie University

Enzymatic reaction of: hypoxanthine transport

Transport reaction diagram for hypoxanthine transport

Inhibitors (Competitive): guanine (Kic = 3µM) [Papakostas13] , N1-methylguanine (Kic = 105µM) [Papakostas13] , thioguanine (Kic = 4µM) [Papakostas13] , azaguanine (Kic = 154µM) [Papakostas13] , mercaptopurine (Kic = 51µM) [Papakostas13]

Kinetic Parameters:

Km (μM)
Vmax (µmol mg-1 min-1)

Enzymatic reaction of: guanine transport (guanine / hypoxanthine transporter GhxQ)

Transport reaction diagram for guanine transport

Kinetic Parameters:

Km (μM)
Vmax (µmol mg-1 min-1)

Sequence Features

Protein sequence of guanine / hypoxanthine transporter GhxQ with features indicated

Feature Class Location Citations Comment
Transmembrane-Region 32 -> 55
UniProt: Helical.
Transmembrane-Region 66 -> 84
UniProt: Helical.
Transmembrane-Region 87 -> 103
UniProt: Discontinuously helical.
Transmembrane-Region 116 -> 135
UniProt: Helical.
Transmembrane-Region 148 -> 168
UniProt: Helical.
Transmembrane-Region 187 -> 204
UniProt: Helical.
Transmembrane-Region 209 -> 228
UniProt: Helical.
Transmembrane-Region 261 -> 289
UniProt: Helical.
Transmembrane-Region 303 -> 318
UniProt: Helical.
Transmembrane-Region 321 -> 336
UniProt: Discontinuously helical.
Transmembrane-Region 341 -> 355
UniProt: Helical.
Transmembrane-Region 367 -> 386
UniProt: Helical.
Intramembrane-Region 392 -> 427
UniProt: Discontinuously helical.

Gene Local Context (not to scale): ?

Gene local context diagram

Transcription Unit:

Transcription-unit diagram


10/21/2004 (paley) Merged genes G7504/ygfR into G7503/ygfQ
Markus Krummenacker on Tue Oct 14, 1997:
Gene object created from Blattner lab Genbank (v. M52) entry.
Peter D. Karp on Thu Jan 16, 2003:
Predicted gene function revised as a result of E. coli genome reannotation by Serres et al. [Serres01 ].
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

Daley05: Daley DO, Rapp M, Granseth E, Melen K, Drew D, von Heijne G (2005). "Global topology analysis of the Escherichia coli inner membrane proteome." Science 308(5726);1321-3. PMID: 15919996

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

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

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

Papakostas13: Papakostas K, Botou M, Frillingos S (2013). "Functional identification of the hypoxanthine/guanine transporters YjcD and YgfQ and the adenine transporters PurP and YicO of Escherichia coli K-12." J Biol Chem 288(52);36827-40. PMID: 24214977

Sabina03: Sabina J, Dover N, Templeton LJ, Smulski DR, Soll D, LaRossa RA (2003). "Interfering with different steps of protein synthesis explored by transcriptional profiling of Escherichia coli K-12." J Bacteriol 185(20);6158-70. PMID: 14526028

Saier09: Saier MH, Yen MR, Noto K, Tamang DG, Elkan C (2009). "The Transporter Classification Database: recent advances." Nucleic Acids Res 37(Database issue);D274-8. PMID: 19022853

Serres01: Serres MH, Gopal S, Nahum LA, Liang P, Gaasterland T, Riley M (2001). "A functional update of the Escherichia coli K-12 genome." Genome Biol 2(9);RESEARCH0035. PMID: 11574054

Thompson07: Thompson KM, Rhodius VA, Gottesman S (2007). "{sigma}E Regulates and Is Regulated by a Small RNA in Escherichia coli." J Bacteriol 189(11);4243-56. PMID: 17416652

Tucker02: Tucker DL, Tucker N, Conway T (2002). "Gene expression profiling of the pH response in Escherichia coli." J Bacteriol 184(23);6551-8. PMID: 12426343

UniProt15: UniProt Consortium (2015). "UniProt version 2015-01 released on 2015-01-16 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."

Xi00: Xi H, Schneider BL, Reitzer L (2000). "Purine catabolism in Escherichia coli and function of xanthine dehydrogenase in purine salvage." J Bacteriol 182(19);5332-41. PMID: 10986234

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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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