|Gene:||eno||Accession Numbers: EG10258 (EcoCyc), b2779, ECK2773|
Component of: degradosome (extended summary available)
Subunit composition of enolase = [Eno]2
Enolase catalyzes the interconversion of 2-phosphoglycerate and phosphoenolpyruvate. It is also a component of the degradosome, a complex that degrades RNA.
Enolase dimerizes, with two active sites per dimer. It is dependent on Mg ion for its structure and denatures in the absence of Mg.[Spring71] The crystal structure of enolase was initially determined to a resolution of 2.5 Å, revealing that its dimer interface is enriched in charged residues relative to typical protein-protein interfaces [Kuhnel01]. A more recent 1.6 Å structure shows enolase bound to its recognition site on RNase E [Chandran06].
Enolase is functionally similar to enolases in other organisms, notably in its dependence on Mg, inhibition by fluoride ion in the presence of phosphate and in its catalytic parameters. Its pH optimum is significantly higher than vertebrate enolases and is somewhat above those of yeast and plant enolases. [Spring71]
Enolase is required for the rapid, degradosome-mediated degradation of ptsG mRNA in response to high levels of glucose 6-P or fructose 6-P [Morita04].
Gene Citations: [Shimada05]
Locations: cytosol, extracellular space, cytoskeleton, membrane
|Map Position: [2,904,665 <- 2,905,963] (62.6 centisomes)||Length: 1299 bp / 432 aa|
Molecular Weight of Polypeptide: 45.655 kD (from nucleotide sequence)
pI: 5.64, 5.7
Unification Links: ASAP:ABE-0009110 , CGSC:823 , DIP:DIP-31847N , EchoBASE:EB0254 , EcoGene:EG10258 , EcoliWiki:b2779 , Mint:MINT-1230935 , ModBase:P0A6P9 , OU-Microarray:b2779 , PortEco:eno , PR:PRO_000022518 , Pride:P0A6P9 , Protein Model Portal:P0A6P9 , RefSeq:NP_417259 , RegulonDB:EG10258 , SMR:P0A6P9 , String:511145.b2779 , UniProt:P0A6P9
Relationship Links: InterPro:IN-FAMILY:IPR000941 , InterPro:IN-FAMILY:IPR020809 , InterPro:IN-FAMILY:IPR020810 , InterPro:IN-FAMILY:IPR020811 , Panther:IN-FAMILY:PTHR11902 , PDB:Structure:1E9I , PDB:Structure:2FYM , PDB:Structure:3H8A , Pfam:IN-FAMILY:PF00113 , Pfam:IN-FAMILY:PF03952 , Prints:IN-FAMILY:PR00148 , Prosite:IN-FAMILY:PS00164
|Biological Process:||GO:0006096 - glycolytic process [UniProtGOA12, UniProtGOA11a, GOA06, GOA01a, Irani77]|
|Molecular Function:||GO:0000287 - magnesium ion binding
[GOA06, GOA01a, Chandran06]
GO:0004634 - phosphopyruvate hydratase activity [GOA06, GOA01, GOA01a, Poyner02, Spring71]
GO:0005515 - protein binding [AitBara10, Chandran06, Regonesi06, Butland05, Callaghan04]
GO:0042802 - identical protein binding [Lasserre06, Callaghan04]
GO:0016829 - lyase activity [UniProtGOA11a]
GO:0046872 - metal ion binding [UniProtGOA11a]
|Cellular Component:||GO:0005829 - cytosol
[DiazMejia09, Ishihama08, Zhang07a, LopezCampistrou05, Lasserre06]
GO:0016020 - membrane [Lasserre06]
GO:0000015 - phosphopyruvate hydratase complex [GOA01a]
GO:0005576 - extracellular region [UniProtGOA11, UniProtGOA11a]
GO:0005737 - cytoplasm [UniProtGOA11a, GOA06]
GO:0005856 - cytoskeleton [UniProtGOA11, UniProtGOA11a]
GO:0009986 - cell surface [UniProtGOA11, GOA06]
|MultiFun Terms:||metabolism → central intermediary metabolism|
|metabolism → energy metabolism, carbon → glycolysis|
|Growth Medium||Growth?||T (°C)||O2||pH||Osm/L||Growth Observations|
|LB Lennox||No||37||Aerobic||7||No [Baba06, Comment 1]|
Enzymatic reaction of: enolase
Synonyms: phosphopyruvate hydratase, 2-phosphoglycerate dehydratase, 2,3-diphospho-D-glycerate, 2-phospho-D glycerate phosphotransferase, 2-phospho-D-glycerate hydrolyase
EC Number: 18.104.22.168
The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the direction in which it was curated.
This reaction is reversible.
In Pathways: superpathway of hexitol degradation (bacteria) , superpathway of glycolysis and Entner-Doudoroff , superpathway of glycolysis, pyruvate dehydrogenase, TCA, and glyoxylate bypass , gluconeogenesis I , glycolysis II (from fructose-6P) , glycolysis I (from glucose-6P)
Cofactor Binding Comment: Magnesium is required for catalysis and stabilizing the dimer. There is an absolute dependence on divalent cations for activity.[Spring71]
Subunit of: degradosome
Subunit composition of
degradosome = [(Ppk)2][(Rne)4][(RhlB)2][(Pnp)3][(Eno)2]
polyphosphate kinase = (Ppk)2 (extended summary available)
ribonuclease E = (Rne)4 (extended summary available)
RNase E = Rne
RhlB, ATP-dependent RNA helicase of the RNA degradosome = (RhlB)2 (extended summary available)
polynucleotide phosphorylase = (Pnp)3 (extended summary available)
polynucleotide phosphorylase monomer = Pnp
enolase = (Eno)2 (extended summary available)
The degradosome is a large, multiprotein complex involved in RNA degradation. It consists of the RNA degradation enzymes RNase E and PNPase, as well as the ATP-dependent RNA helicase RhlB and the metabolic enzyme enolase [Py94, Carpousis94, Py96]. Polyphosphate kinase and the chaperone protein DnaK are also associated with and may be components of the degradosome [Blum97, Miczak96]. A "minimal" degradosome composed of only RNase E, PNPase and RhlB degrades malEF REP RNA in an ATP-dependent manner in vitro, with activity equivalent to purified whole degradosomes. RNase E enzymatic function is dispensible for this test case, whereas PNPase must be catalytically active and incorporated into the degradosome for degradation to occur [Coburn99]. Based on immunogold labeling studies, RhlB and RNase E are present in equimolar quantities in the degradosome, which is tethered to the cytoplasmic membrane via the amino-terminus of RNase E [Liou01].
RNase E provides the organizational structure for the degradosome. Its carboxy-terminal half binds PNPase, RhlB and enolase, and the loss of this portion of the protein prevents degradation of a number of degradosome substrates, including the ptsG and mukB mRNAs and RNA I [Kido96, Vanzo98, Morita04]. This scaffold region is flexible, with isolated segments of increased structure that may be involved in binding other degradosome constituents [Callaghan04]. RNase E binding to partner proteins can be selectively disrupted. Loss of RhlB and enolase binding results in reduced degradosome activity. Conversely, disrupted PNPase binding yields increased activity. Strains any alteration in RNase E binding do not grow as well as wild type [Leroy02]. The amino-terminal half of RNase E contains sequences involved in oligomerization [Vanzo98].
In vitro purified degradosome generates 147-nucleotide RNase E cleavage intermediates from rpsT mRNA. Continuous cycles of polyadenylation and PNPase cleavage are necessary and sufficient to break down these intermediates, though RNase II can block this second degradation step [Coburn98]. RNAs with 3' REP stabilizers or stem loops must be polyadenylated to allow breakdown by the degradosome [Khemici04, Blum99]. Poly(G) and poly(U) tails do not allow degradation, though addition of a stretch of mixed nucleotides copied from within a coding region has stimulated degradation of a test substrate [Blum99].
The DEAD-box helicases SrmB, RhlE and CsdA bind RNase E in vitro at a different site than RhlB. RhlE and CsdA can both replace RhlB in promoting PNPase activity in vitro [Khemici04a]. CsdA is induced by cold shock, and following a shift to 15 degrees C it copurifies with the degradosome [PrudhommeGenere04].
At least two poly(A)-binding proteins interact with the degradosome. The cold-shock protein CspE inhibits internal cleavage and breakdown of polyadenylated RNA by RNase E and PNPase by blocking digestion through the poly(A) tail. S1, a component of the 30S ribosome, binds to RNase E and PNPase without apparent effect on their activities [Feng01].
The global effects of mutations in degradeosome constituents on mRNA levels have been evaluated using microarrays [Bernstein04].
Locations: inner membrane
|Cellular Component:||GO:0005886 - plasma membrane [Liou01]|
|Chain||2 -> 432|
|Protein-Segment||5 -> 34|
|Protein-Segment||369 -> 372|
|Sequence-Conflict||421 -> 432|
10/20/97 Gene b2779 from Blattner lab Genbank (v. M52) entry merged into EcoCyc gene EG10258; confirmed by SwissProt match.
AitBara10: Ait-Bara S, Carpousis AJ (2010). "Characterization of the RNA degradosome of Pseudoalteromonas haloplanktis: conservation of the RNase E-RhlB interaction in the gammaproteobacteria." J Bacteriol 192(20);5413-23. PMID: 20729366
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
Bernstein04: Bernstein JA, Lin PH, Cohen SN, Lin-Chao S (2004). "Global analysis of Escherichia coli RNA degradosome function using DNA microarrays." Proc Natl Acad Sci U S A 101(9);2758-63. PMID: 14981237
Bessarab98: Bessarab DA, Kaberdin VR, Wei CL, Liou GG, Lin-Chao S (1998). "RNA components of Escherichia coli degradosome: evidence for rRNA decay." Proc Natl Acad Sci U S A 95(6);3157-61. PMID: 9501232
Blum99: Blum E, Carpousis AJ, Higgins CF (1999). "Polyadenylation promotes degradation of 3'-structured RNA by the Escherichia coli mRNA degradosome in vitro." J Biol Chem 274(7);4009-16. PMID: 9933592
Boel04: Boel G, Pichereau V, Mijakovic I, Maze A, Poncet S, Gillet S, Giard JC, Hartke A, Auffray Y, Deutscher J (2004). "Is 2-phosphoglycerate-dependent automodification of bacterial enolases implicated in their export?." J Mol Biol 337(2);485-96. PMID: 15003462
Butland05: Butland G, Peregrin-Alvarez JM, Li J, Yang W, Yang X, Canadien V, Starostine A, Richards D, Beattie B, Krogan N, Davey M, Parkinson J, Greenblatt J, Emili A (2005). "Interaction network containing conserved and essential protein complexes in Escherichia coli." Nature 433(7025);531-7. PMID: 15690043
Callaghan04: Callaghan AJ, Aurikko JP, Ilag LL, Gunter Grossmann J, Chandran V, Kuhnel K, Poljak L, Carpousis AJ, Robinson CV, Symmons MF, Luisi BF (2004). "Studies of the RNA degradosome-organizing domain of the Escherichia coli ribonuclease RNase E." J Mol Biol 340(5);965-79. PMID: 15236960
Carpousis94: Carpousis AJ, Van Houwe G, Ehretsmann C, Krisch HM (1994). "Copurification of E. coli RNAase E and PNPase: evidence for a specific association between two enzymes important in RNA processing and degradation." Cell 76(5);889-900. PMID: 7510217
Coburn99: Coburn GA, Miao X, Briant DJ, Mackie GA (1999). "Reconstitution of a minimal RNA degradosome demonstrates functional coordination between a 3' exonuclease and a DEAD-box RNA helicase." Genes Dev 13(19);2594-603. PMID: 10521403
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
Feng01: Feng Y, Huang H, Liao J, Cohen SN (2001). "Escherichia coli poly(A)-binding proteins that interact with components of degradosomes or impede RNA decay mediated by polynucleotide phosphorylase and RNase E." J Biol Chem 276(34);31651-6. PMID: 11390393
Khemici04: Khemici V, Carpousis AJ (2004). "The RNA degradosome and poly(A) polymerase of Escherichia coli are required in vivo for the degradation of small mRNA decay intermediates containing REP-stabilizers." Mol Microbiol 51(3);777-90. PMID: 14731278
Khemici04a: Khemici V, Toesca I, Poljak L, Vanzo NF, Carpousis AJ (2004). "The RNase E of Escherichia coli has at least two binding sites for DEAD-box RNA helicases: functional replacement of RhlB by RhlE." Mol Microbiol 54(5);1422-30. PMID: 15554979
Kido96: Kido M, Yamanaka K, Mitani T, Niki H, Ogura T, Hiraga S (1996). "RNase E polypeptides lacking a carboxyl-terminal half suppress a mukB mutation in Escherichia coli." J Bacteriol 178(13);3917-25. PMID: 8682798
Lasserre06: Lasserre JP, Beyne E, Pyndiah S, Lapaillerie D, Claverol S, Bonneu M (2006). "A complexomic study of Escherichia coli using two-dimensional blue native/SDS polyacrylamide gel electrophoresis." Electrophoresis 27(16);3306-21. PMID: 16858726
Leroy02: Leroy A, Vanzo NF, Sousa S, Dreyfus M, Carpousis AJ (2002). "Function in Escherichia coli of the non-catalytic part of RNase E: role in the degradation of ribosome-free mRNA." Mol Microbiol 45(5);1231-43. PMID: 12207692
LinChao99: Lin-Chao S, Wei CL, Lin YT (1999). "RNase E is required for the maturation of ssrA RNA and normal ssrA RNA peptide-tagging activity." Proc Natl Acad Sci U S A 96(22);12406-11. PMID: 10535935
Link97: Link AJ, Robison K, Church GM (1997). "Comparing the predicted and observed properties of proteins encoded in the genome of Escherichia coli K-12." Electrophoresis 18(8);1259-313. PMID: 9298646
Liou01: Liou GG, Jane WN, Cohen SN, Lin NS, Lin-Chao S (2001). "RNA degradosomes exist in vivo in Escherichia coli as multicomponent complexes associated with the cytoplasmic membrane via the N-terminal region of ribonuclease E." Proc Natl Acad Sci U S A 98(1);63-8. PMID: 11134527
LopezCampistrou05: Lopez-Campistrous A, Semchuk P, Burke L, Palmer-Stone T, Brokx SJ, Broderick G, Bottorff D, Bolch S, Weiner JH, Ellison MJ (2005). "Localization, annotation, and comparison of the Escherichia coli K-12 proteome under two states of growth." Mol Cell Proteomics 4(8);1205-9. PMID: 15911532
Morita04: Morita T, Kawamoto H, Mizota T, Inada T, Aiba H (2004). "Enolase in the RNA degradosome plays a crucial role in the rapid decay of glucose transporter mRNA in the response to phosphosugar stress in Escherichia coli." Mol Microbiol 54(4);1063-75. PMID: 15522087
Poyner02: Poyner RR, Larsen TM, Wong SW, Reed GH (2002). "Functional and structural changes due to a serine to alanine mutation in the active-site flap of enolase." Arch Biochem Biophys 401(2);155-63. PMID: 12054465
PrudhommeGenere04: Prud'homme-Genereux A, Beran RK, Iost I, Ramey CS, Mackie GA, Simons RW (2004). "Physical and functional interactions among RNase E, polynucleotide phosphorylase and the cold-shock protein, CsdA: evidence for a 'cold shock degradosome'." Mol Microbiol 54(5);1409-21. PMID: 15554978
Regonesi06: Regonesi ME, Del Favero M, Basilico F, Briani F, Benazzi L, Tortora P, Mauri P, Deho G (2006). "Analysis of the Escherichia coli RNA degradosome composition by a proteomic approach." Biochimie 88(2);151-61. PMID: 16139413
Vanzo98: Vanzo NF, Li YS, Py B, Blum E, Higgins CF, Raynal LC, Krisch HM, Carpousis AJ (1998). "Ribonuclease E organizes the protein interactions in the Escherichia coli RNA degradosome." Genes Dev 12(17);2770-81. PMID: 9732274
Wilkins98: Wilkins MR, Gasteiger E, Tonella L, Ou K, Tyler M, Sanchez JC, Gooley AA, Walsh BJ, Bairoch A, Appel RD, Williams KL, Hochstrasser DF (1998). "Protein identification with N and C-terminal sequence tags in proteome projects." J Mol Biol 278(3);599-608. PMID: 9600841
Zhang07a: Zhang N, Chen R, Young N, Wishart D, Winter P, Weiner JH, Li L (2007). "Comparison of SDS- and methanol-assisted protein solubilization and digestion methods for Escherichia coli membrane proteome analysis by 2-D LC-MS/MS." Proteomics 7(4);484-93. PMID: 17309111
Zhang09a: Zhang J, Sprung R, Pei J, Tan X, Kim S, Zhu H, Liu CF, Grishin NV, Zhao Y (2009). "Lysine acetylation is a highly abundant and evolutionarily conserved modification in Escherichia coli." Mol Cell Proteomics 8(2);215-25. PMID: 18723842
MendozaVargas09: Mendoza-Vargas A, Olvera L, Olvera M, Grande R, Vega-Alvarado L, Taboada B, Jimenez-Jacinto V, Salgado H, Juarez K, Contreras-Moreira B, Huerta AM, Collado-Vides J, Morett E (2009). "Genome-wide identification of transcription start sites, promoters and transcription factor binding sites in E. coli." PLoS One 4(10);e7526. PMID: 19838305
Olvera09: Olvera L, Mendoza-Vargas A, Flores N, Olvera M, Sigala JC, Gosset G, Morett E, Bolivar F (2009). "Transcription analysis of central metabolism genes in Escherichia coli. Possible roles of sigma38 in their expression, as a response to carbon limitation." PLoS One 4(10);e7466. PMID: 19838295
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