Escherichia coli K-12 substr. MG1655 Transporter: water channel AqpZ

Gene: aqpZ Accession Numbers: EG13270 (EcoCyc), b0875, ECK0866

Synonyms: bniP, AqpZ water MIP channel

Regulation Summary Diagram: ?

Regulation summary diagram for aqpZ

Subunit composition of water channel AqpZ = [AqpZ]4
         AqpZ monomer = AqpZ

AqpZ is a water channel, or aquaporin, that allows bi-directional passive diffusion of water in E. coli. It is a member of the Major Intrinsic Protein (MIP) family, a large and diverse family of transmembrane channels that transport a range of substrates by energy independent mechanisms [Saier14]. AqpZ mediates the rapid entry or exit of water in response to changes in extracellular osmolarity [Delamarche99].

AqpZ structure has been analysed by electron microscopy [Ringler99], atomic force microscopy [Scheuring99] and x-ray crystallography [Savage03, Daniels04, Savage07, Jiang06b]. AqpZ contains 6 transmembrane helices and two half membrane helices with the N and C-termini located in the cytoplasm. AqpZ forms homotetramers of 4 monomer channels. The monomer channel adopts an 'hour-glass' structure with periplasmic and cytoplasmic conical shaped vestibules connected by a narrow central amphipathic pore which constitutes a water conduction pathway. A selectivity filter, formed by the side chains of Phe43, His174, Arg189 and Thr183 is located at the narrowest point in the channel. Two distinct conformations of the channel have been obtained, differentiated by the side chain displacement of Arg189. The conformations may represent open and closed forms of the channel or they could be dynamic conformations occurring during water permeation.

Purified AqpZ, reconstituted into proteoliposomes, displays high osmotic water permeability [Borgnia99]. Expression of aqpZ in Xenopus oocytes, produces a marked increase in osmotic water permeability [Calamita95]. Expression of aqpZ from a plasmid increases osmotic water permeability [Hubert05]. An aqpZ::lacZ-kan knockout mutant is viable but forms small colonies in rich and minimal media and has reduced viability in hypotonic media [Calamita98]. No phenotypic effect could be detected in an aqpZ::cam knockout strain under a range of conditions [Soupene02].

Cardiolipin stabilises and modulates the function of AqpZ [Laganowsky14].

aqpZ mRNA is monocistronic. Expression of aqpZ-lacZ from a low copy plasmid peaks during mid logarithmic growth and is dependent upon the extracellular osmolality [Calamita98]. Expression of a chromosomal aqpZ-lacZ fusion is independent of osmolality and increases in a σS-dependent manner as cell growth enters the stationary phase [Soupene02].

Reviews: [Calamita00a, Hedfalk06, Wood06a]

Citations: [Fushimi97, Scheuring00, Borgnia01, Pohl01, Scheuring02, Stroud03, Mohanty04, Wang05d, Mallo06, Jensen06, Hashido05, Hu12, Savage10]

Locations: inner membrane

Map Position: [914,575 <- 915,270] (19.71 centisomes, 71°)
Length: 696 bp / 231 aa

Molecular Weight of Polypeptide: 23.703 kD (from nucleotide sequence), 20.0 kD (experimental) [Calamita97 ]

Molecular Weight of Multimer: 80.0 kD (experimental) [Borgnia99]

Unification Links: ASAP:ABE-0002976 , DIP:DIP-35499N , EchoBASE:EB3055 , EcoGene:EG13270 , EcoliWiki:b0875 , ModBase:P60844 , OU-Microarray:b0875 , PortEco:aqpZ , PR:PRO_000022113 , Protein Model Portal:P60844 , RefSeq:NP_415396 , RegulonDB:EG13270 , SMR:P60844 , String:511145.b0875 , UniProt:P60844

Relationship Links: InterPro:IN-FAMILY:IPR000425 , InterPro:IN-FAMILY:IPR022357 , InterPro:IN-FAMILY:IPR023271 , InterPro:IN-FAMILY:IPR023743 , Panther:IN-FAMILY:PTHR19139 , PDB:Structure:1RC2 , PDB:Structure:2abm , PDB:Structure:2o9d , PDB:Structure:2o9e , PDB:Structure:2o9f , PDB:Structure:2o9g , PDB:Structure:3NK5 , PDB:Structure:3NKA , PDB:Structure:3NKC , Pfam:IN-FAMILY:PF00230 , Prints:IN-FAMILY:PR00783 , Prosite:IN-FAMILY:PS00221

In Paralogous Gene Group: 220 (2 members)

Gene-Reaction Schematic: ?

Gene-Reaction Schematic

GO Terms:

Biological Process: GO:0006833 - water transport Inferred from experiment Inferred by computational analysis [GOA01a, Borgnia99, Savage03, Mallo06, Delamarche99]
GO:0006970 - response to osmotic stress Inferred from experiment [Calamita98, Delamarche99]
GO:0009992 - cellular water homeostasis Inferred from experiment [Delamarche99, Calamita98]
GO:0006810 - transport Inferred by computational analysis [UniProtGOA11a, GOA01a]
GO:0015793 - glycerol transport Inferred by computational analysis [Gaudet10]
GO:0034220 - ion transmembrane transport Inferred by computational analysis [Gaudet10]
GO:0055085 - transmembrane transport Inferred by computational analysis [GOA01a]
Molecular Function: GO:0005515 - protein binding Inferred from experiment [Jiang06b]
GO:0015250 - water channel activity Inferred from experiment Inferred by computational analysis [GOA06, GOA01a, Borgnia99, Savage03, Delamarche99]
GO:0042802 - identical protein binding Inferred from experiment [Borgnia99, Jiang06b]
GO:0005215 - transporter activity Inferred by computational analysis [GOA01a]
GO:0015254 - glycerol channel activity Inferred by computational analysis [Gaudet10]
Cellular Component: GO:0005886 - plasma membrane Inferred from experiment Inferred by computational analysis [UniProtGOA11, UniProtGOA11a, GOA06, DiazMejia09, Daley05]
GO:0005887 - integral component of plasma membrane Inferred from experiment Inferred by computational analysis [Gaudet10, Borgnia99]
GO:0016021 - integral component of membrane Inferred from experiment Inferred by computational analysis [UniProtGOA11a, GOA01a, Romantsov10]
GO:0016020 - membrane Inferred by computational analysis [UniProtGOA11a, GOA01a]

MultiFun Terms: cell processes adaptations osmotic pressure
cell structure membrane
transport Channel-type Transporters alpha-type channels

Essentiality data for aqpZ 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]
Yes [Feist07, Comment 4]

Created 06-Dec-2007 by Johnson A , JCVI
Revised 09-Jul-2014 by Mackie A , Macquarie University
Last-Curated ? 09-Jul-2014 by Mackie A , Macquarie University

Enzymatic reaction of: water channel AqpZ

Transport reaction diagram for water channel AqpZ

Sequence Features

Protein sequence of AqpZ monomer with features indicated

Feature Class Location Common Name Citations Comment
Transmembrane-Region 1 -> 26 M1
Mutagenesis-Variant 9  
[Borgnia99, UniProt11]
UniProt: No effect.
Transmembrane-Region 9 -> 29  
UniProt: Helical; Name=1;; Non-Experimental Qualifier: potential;
Sequence-Conflict 14  
[Fushimi95, UniProt15]
UniProt: (in Ref. 2; BAA08441).
Amino-Acid-Site 20  
UniProt: Involved in tetramerization or stability of the tetramer; Sequence Annotation Type: site.
Mutagenesis-Variant 20  
[Borgnia99, UniProt11]
UniProt: Loss of oligomerization; no alteration of water permeability.
Sequence-Conflict 26  
[Fushimi95, UniProt15]
UniProt: (in Ref. 2; BAA08441).
Transmembrane-Region 34 -> 54  
UniProt: Helical; Name=2;; Non-Experimental Qualifier: potential;
Transmembrane-Region 36 -> 53 M2
Amino-Acid-Site 43  
Selectivity filter
Protein-Segment 63 -> 65  
UniProt: NPA 1; Sequence Annotation Type: short sequence motif.
Transmembrane-Region 63 -> 72 M3
Transmembrane-Region 79 -> 103 M4
Transmembrane-Region 82 -> 102  
UniProt: Helical; Name=3;; Non-Experimental Qualifier: potential;
Sequence-Conflict 99  
[Calamita95, UniProt10a]
UniProt: (in Ref. 1; AAC43518);
Transmembrane-Region 131 -> 151  
UniProt: Helical; Name=4;; Non-Experimental Qualifier: potential;
Transmembrane-Region 131 -> 152 M5
Transmembrane-Region 156 -> 176  
UniProt: Helical; Name=5;; Non-Experimental Qualifier: potential;
Transmembrane-Region 162 -> 181 M6
Amino-Acid-Site 174  
Selectivity filter
Mutagenesis-Variant 183  
[Borgnia99, UniProt11]
UniProt: No effect.
Amino-Acid-Site 183  
Selectivity filter
Protein-Segment 186 -> 188  
UniProt: NPA 2; Sequence Annotation Type: short sequence motif.
Transmembrane-Region 186 -> 197 M7
Mutagenesis-Variant 189  
[Borgnia99, UniProt11]
R → S or V: Loss of function.
Amino-Acid-Site 189  
[Savage03, Jiang06b]
Selectivity filter; two distinct conformations of the side chain of Arg189 were resolved in crystal structures
Transmembrane-Region 202 -> 222  
UniProt: Helical; Name=6;; Non-Experimental Qualifier: potential;
Transmembrane-Region 206 -> 229 M8

Gene Local Context (not to scale): ?

Gene local context diagram

Transcription Unit:

Transcription-unit diagram


10/20/97 Gene b0875 from Blattner lab Genbank (v. M52) entry merged into EcoCyc gene EG13270; confirmed by SwissProt match.


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

Borgnia01: Borgnia MJ, Agre P (2001). "Reconstitution and functional comparison of purified GlpF and AqpZ, the glycerol and water channels from Escherichia coli." Proc Natl Acad Sci U S A 98(5);2888-93. PMID: 11226336

Borgnia99: Borgnia MJ, Kozono D, Calamita G, Maloney PC, Agre P (1999). "Functional reconstitution and characterization of AqpZ, the E. coli water channel protein." J Mol Biol 291(5);1169-79. PMID: 10518952

Calamita00a: Calamita G (2000). "The Escherichia coli aquaporin-Z water channel." Mol Microbiol 2000;37(2);254-62. PMID: 10931322

Calamita95: Calamita G, Bishai WR, Preston GM, Guggino WB, Agre P (1995). "Molecular cloning and characterization of AqpZ, a water channel from Escherichia coli." J Biol Chem 1995;270(49);29063-6. PMID: 7493926

Calamita97: Calamita G, Kempf B, Rudd KE, Bonhivers M, Kneip S, Bishai WR, Bremer E, Agre P (1997). "The aquaporin-Z water channel gene of Escherichia coli: structure, organization and phylogeny." Biol Cell 89(5-6);321-9. PMID: 9468603

Calamita98: Calamita G, Kempf B, Bonhivers M, Bishai WR, Bremer E, Agre P (1998). "Regulation of the Escherichia coli water channel gene aqpZ." Proc Natl Acad Sci U S A 1998;95(7);3627-31. PMID: 9520416

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

Daniels04: Daniels BV, Jiang JS, Fu D (2004). "Crystallization and preliminary crystallographic analysis of the Escherichia coli water channel AqpZ." Acta Crystallogr D Biol Crystallogr 60(Pt 3);561-3. PMID: 14993693

Delamarche99: Delamarche C, Thomas D, Rolland JP, Froger A, Gouranton J, Svelto M, Agre P, Calamita G (1999). "Visualization of AqpZ-mediated water permeability in Escherichia coli by cryoelectron microscopy." J Bacteriol 181(14);4193-7. PMID: 10400575

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

Feist07: Feist AM, Henry CS, Reed JL, Krummenacker M, Joyce AR, Karp PD, Broadbelt LJ, Hatzimanikatis V, Palsson BO (2007). "A genome-scale metabolic reconstruction for Escherichia coli K-12 MG1655 that accounts for 1260 ORFs and thermodynamic information." Mol Syst Biol 3;121. PMID: 17593909

Fushimi95: Fushimi K. (1995). "Cloning and expression of a new member of aquaporin water channel family of E. coli." Data submission to EMBL/GenBank/DDBJ databases on 1995-03.

Fushimi97: Fushimi K, Bai L, Marumo F, Sasaki S (1997). "Isolation of a gene encoding nodulin-like intrinsic protein of Escherichia coli." Biochem Mol Biol Int 41(5);995-1003. PMID: 9137831

Gaudet10: Gaudet P, Livstone M, Thomas P (2010). "Annotation inferences using phylogenetic trees." PMID: 19578431

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."

GOA06: GOA, SIB (2006). "Electronic Gene Ontology annotations created by transferring manual GO annotations between orthologous microbial proteins."

Hashido05: Hashido M, Ikeguchi M, Kidera A (2005). "Comparative simulations of aquaporin family: AQP1, AQPZ, AQP0 and GlpF." FEBS Lett 579(25);5549-52. PMID: 16225876

Hedfalk06: Hedfalk K, Tornroth-Horsefield S, Nyblom M, Johanson U, Kjellbom P, Neutze R (2006). "Aquaporin gating." Curr Opin Struct Biol 16(4);447-56. PMID: 16837191

Hu12: Hu G, Chen LY, Wang J (2012). "Insights into the mechanisms of the selectivity filter of Escherichia coli aquaporin Z." J Mol Model 18(8);3731-41. PMID: 22392432

Hubert05: Hubert JF, Duchesne L, Delamarche C, Vaysse A, Gueune H, Raguenes-Nicol C (2005). "Pore selectivity analysis of an aquaglyceroporin by stopped-flow spectrophotometry on bacterial cell suspensions." Biol Cell 97(9);675-86. PMID: 15859950

Jensen06: Jensen MO, Mouritsen OG (2006). "Single-channel water permeabilities of Escherichia coli aquaporins AqpZ and GlpF." Biophys J 90(7);2270-84. PMID: 16399837

Jiang06b: Jiang J, Daniels BV, Fu D (2006). "Crystal structure of AqpZ tetramer reveals two distinct R189 conformations associated with water permeation through the narrowest constriction of the water-conducting channel." J Biol Chem 281(1):454-60. PMID: 16239219

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

Laganowsky14: Laganowsky A, Reading E, Allison TM, Ulmschneider MB, Degiacomi MT, Baldwin AJ, Robinson CV (2014). "Membrane proteins bind lipids selectively to modulate their structure and function." Nature 510(7503);172-5. PMID: 24899312

Mallo06: Mallo RC, Ashby MT (2006). "AqpZ-mediated water permeability in Escherichia coli measured by stopped-flow spectroscopy." J Bacteriol 188(2);820-2. PMID: 16385074

Mohanty04: Mohanty AK, Wiener MC (2004). "Membrane protein expression and production: effects of polyhistidine tag length and position." Protein Expr Purif 33(2);311-25. PMID: 14711520

Pohl01: Pohl P, Saparov SM, Borgnia MJ, Agre P (2001). "Highly selective water channel activity measured by voltage clamp: analysis of planar lipid bilayers reconstituted with purified AqpZ." Proc Natl Acad Sci U S A 98(17);9624-9. PMID: 11493683

Ringler99: Ringler P, Borgnia MJ, Stahlberg H, Maloney PC, Agre P, Engel A (1999). "Structure of the water channel AqpZ from Escherichia coli revealed by electron crystallography." J Mol Biol 291(5);1181-90. PMID: 10518953

Romantsov10: Romantsov T, Battle AR, Hendel JL, Martinac B, Wood JM (2010). "Protein localization in Escherichia coli cells: comparison of the cytoplasmic membrane proteins ProP, LacY, ProW, AqpZ, MscS, and MscL." J Bacteriol 192(4);912-24. PMID: 20008071

Saier14: Saier MH, Reddy VS, Tamang DG, Vastermark A (2014). "The transporter classification database." Nucleic Acids Res 42(1);D251-8. PMID: 24225317

Savage03: Savage DF, Egea PF, Robles-Colmenares Y, O'Connell JD, Stroud RM (2003). "Architecture and selectivity in aquaporins: 2.5 a X-ray structure of aquaporin Z." PLoS Biol 1(3);E72. PMID: 14691544

Savage07: Savage DF, Stroud RM (2007). "Structural basis of aquaporin inhibition by mercury." J Mol Biol 368(3);607-17. PMID: 17376483

Savage10: Savage DF, O'Connell JD, Miercke LJ, Finer-Moore J, Stroud RM (2010). "Structural context shapes the aquaporin selectivity filter." Proc Natl Acad Sci U S A 107(40);17164-9. PMID: 20855585

Scheuring00: Scheuring S, Tittmann P, Stahlberg H, Ringler P, Borgnia M, Agre P, Gross H, Engel A (2000). "The aquaporin sidedness revisited." J Mol Biol 299(5);1271-8. PMID: 10873451

Scheuring02: Scheuring S, Muller DJ, Stahlberg H, Engel HA, Engel A (2002). "Sampling the conformational space of membrane protein surfaces with the AFM." Eur Biophys J 31(3);172-8. PMID: 12029329

Scheuring99: Scheuring S, Ringler P, Borgnia M, Stahlberg H, Muller DJ, Agre P, Engel A (1999). "High resolution AFM topographs of the Escherichia coli water channel aquaporin Z." EMBO J 18(18);4981-7. PMID: 10487750

Soupene02: Soupene E, King N, Lee H, Kustu S (2002). "Aquaporin Z of Escherichia coli: reassessment of its regulation and physiological role." J Bacteriol 184(15);4304-7. PMID: 12107150

Stroud03: Stroud RM, Savage D, Miercke LJ, Lee JK, Khademi S, Harries W (2003). "Selectivity and conductance among the glycerol and water conducting aquaporin family of channels." FEBS Lett 555(1);79-84. PMID: 14630323

UniProt10: UniProt Consortium (2010). "UniProt version 2010-07 released on 2010-06-15 00:00:00." Database.

UniProt10a: UniProt Consortium (2010). "UniProt version 2010-11 released on 2010-11-02 00:00:00." Database.

UniProt11: UniProt Consortium (2011). "UniProt version 2011-06 released on 2011-06-30 00:00:00." Database.

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."

Wang05d: Wang Y, Schulten K, Tajkhorshid E (2005). "What makes an aquaporin a glycerol channel? A comparative study of AqpZ and GlpF." Structure 13(8);1107-18. PMID: 16084383

Wood06a: Wood JM (2006). "Osmosensing by bacteria." Sci STKE 2006(357);pe43. PMID: 17047223

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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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