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MetaCyc Polypeptide: IlvI

Gene: ilvI Accession Numbers: EG10500 (MetaCyc), b0077, ECK0079

Species: Escherichia coli K-12 substr. MG1655

Component of: acetolactate synthase / acetohydroxybutanoate synthase (extended summary available)

Summary:
IlvI is the large catalytic subunit of the bifunctional acetohydroxybutanoate synthase /acetolactate synthase (IlvI/H, AHAS III) which carries out both the first step in valine biosynthesis and the second step in isoleucine biosynthesis. The IlvI/H protein complex catalyzes the conversion of pyruvate and oxobutanoate into 2-aceto-2-hydroxy-butyrate and the conversion of pyruvate into 2-acetolactate. Both reactions generate carbon dioxide as a product. [De74, Gollop89, Barak87, Vyazmensky96, Weinstock92]

C-terminal and N-terminal ilvH mutants were constructed and used to determine the minimum activation peptide necessary to activate IlvI [Zhao13a]. Interactions between large and small subunits of different AHAS isozymes were investigated. IlvI could be activated by IlvM just as well as IlvH. [Vyazmensky09]

Isolated IlvI has only 5% of the molar activity of its holoenzyme. However, isolated IlvI has similar substrate specificity and similar cofactor dependence as its holoenzyme. Assembly of the holoenzyme requires FAD. [Vyazmensky96]

Gene Citations: [Haughn85]

Locations: cytosol

Map Position: [85,630 -> 87,354]

Molecular Weight of Polypeptide: 62.984 kD (from nucleotide sequence), 60 kD (experimental) [Vyazmensky96 ]

Unification Links: ASAP:ABE-0000290 , CGSC:601 , DIP:DIP-6850N , EchoBASE:EB0495 , EcoGene:EG10500 , EcoliWiki:b0077 , ModBase:P00893 , OU-Microarray:b0077 , PortEco:ilvI , PR:PRO_000023008 , Pride:P00893 , Protein Model Portal:P00893 , RefSeq:YP_025294 , RegulonDB:EG10500 , SMR:P00893 , String:511145.b0077 , UniProt:P00893

Relationship Links: InterPro:IN-FAMILY:IPR000399 , InterPro:IN-FAMILY:IPR011766 , InterPro:IN-FAMILY:IPR012000 , InterPro:IN-FAMILY:IPR012001 , InterPro:IN-FAMILY:IPR012846 , Panther:IN-FAMILY:PTHR18968:SF13 , Pfam:IN-FAMILY:PF00205 , Pfam:IN-FAMILY:PF02775 , Pfam:IN-FAMILY:PF02776 , Prosite:IN-FAMILY:PS00187

Gene-Reaction Schematic: ?

GO Terms:

Biological Process: GO:0009097 - isoleucine biosynthetic process Inferred from experiment Inferred by computational analysis [UniProtGOA12, Gollop89]
GO:0009099 - valine biosynthetic process Inferred from experiment Inferred by computational analysis [UniProtGOA12, Gollop89]
GO:0008652 - cellular amino acid biosynthetic process Inferred by computational analysis [UniProtGOA11a]
GO:0009082 - branched-chain amino acid biosynthetic process Inferred by computational analysis [UniProtGOA11a, GOA01a]
Molecular Function: GO:0000287 - magnesium ion binding Inferred from experiment Inferred by computational analysis [GOA01a, Vyazmensky96]
GO:0003984 - acetolactate synthase activity Inferred from experiment Inferred by computational analysis [GOA01, GOA01a, De74, Gollop89]
GO:0030976 - thiamine pyrophosphate binding Inferred from experiment Inferred by computational analysis [GOA01a, Vyazmensky96]
GO:0050660 - flavin adenine dinucleotide binding Inferred from experiment Inferred by computational analysis [GOA01a, Vyazmensky96]
GO:0003824 - catalytic activity Inferred by computational analysis [GOA01a]
GO:0016740 - transferase activity Inferred by computational analysis [UniProtGOA11a]
GO:0046872 - metal ion binding Inferred by computational analysis [UniProtGOA11a]
Cellular Component: GO:0005829 - cytosol Inferred from experiment Inferred by computational analysis [DiazMejia09, Ishihama08]

MultiFun Terms: metabolism biosynthesis of building blocks amino acids isoleucine/valine

Credits:
Imported from EcoCyc 16-Sep-2014 by Paley S , SRI International


Subunit of: acetolactate synthase / acetohydroxybutanoate synthase

Synonyms: acetolactate synthase III, acetohydroxy acid synthase III, AHAS III, acetohydroxybutanoate synthase III

Species: Escherichia coli K-12 substr. MG1655

Subunit composition of acetolactate synthase / acetohydroxybutanoate synthase = [IlvI]2[IlvH]2

Summary:
Acetohydroxy acid synthase III (AHAS III) is one of two functional isozymes catalyzing the decarboxylation of pyruvate and transfer of the resulting acetaldehyde group to either pyruvate or α-ketobutyrate, producing α-acetolactate for the valine pathway and α-aceto-α-hydroxybutyrate for the isoleucine pathway. This is the first common step in the biosynthesis of the branched-chain amino acids isoleucine, leucine, and valine. A third isozyme, AHAS II, is not functional in E. coli K-12 due to the presence of a frame shift mutation in the gene encoding the large subunit, ilvG. [Neidhardt96]

In the presence of both pyruvate and α-ketobutyrate, AHAS III produces approximately 40-fold more acetohydroxybutyrate than acetolactate, while AHAS I shows no product preference [Barak87, Gollop89].

The differential regulation of enzymatic activity and expression of the isozymes has direct physiological consequences and has been under intense study. The end products of the branched-chain amino acid biosynthesis pathways all inhibit AHAS III activity, although inhibition by valine is most significant [Gollop89]. Both AHAS I and III are inhibited by valine [De78]. Activity of AHAS III is only partially inhibited by leucine, while AHAS I activity can be almost completely inhibited [Gollop83].

Molecular Weight: 155 kD (experimental) [Vyazmensky96]

Credits:
Imported from EcoCyc 16-Sep-2014 by Paley S , SRI International


Enzymatic reaction of: acetolactate synthase

Synonyms: acetolactate pyruvate-lyase (carboxylating), acetohydroxy acid synthase

EC Number: 2.2.1.6

2 pyruvate + H+ <=> (S)-2-acetolactate + CO2

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

This reaction is reversible.

In Pathways: superpathway of leucine, valine, and isoleucine biosynthesis , pyruvate fermentation to isobutanol (engineered) , valine biosynthesis

Credits:
Imported from EcoCyc 16-Sep-2014 by Paley S , SRI International

Cofactors or Prosthetic Groups: thiamin diphosphate [De78, Vyazmensky96], FAD [Vyazmensky96], Mg2+ [Vyazmensky96]

Inhibitors (Unknown Mechanism): sulfometuron methyl [Barak88] , L-isoleucine [Barak88] , L-valine [Gollop89] , L-leucine

Primary Physiological Regulators of Enzyme Activity: L-isoleucine , L-valine , L-leucine

Kinetic Parameters:

Substrate
Km (μM)
Citations
pyruvate
6000.0
[Gollop89]

pH(opt): 9 [De78]


Enzymatic reaction of: acetohydroxybutanoate synthase

Synonyms: acetohydroxybutyrate pyruvate-lyase (carboxylating)

EC Number: 2.2.1.6

pyruvate + 2-oxobutanoate + H+ <=> (S)-2-aceto-2-hydroxybutanoate + CO2

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 favored in the direction shown.

In Pathways: isoleucine biosynthesis I , superpathway of threonine metabolism , superpathway of leucine, valine, and isoleucine biosynthesis , isoleucine biosynthesis I (from threonine)

Credits:
Imported from EcoCyc 16-Sep-2014 by Paley S , SRI International

Cofactors or Prosthetic Groups: thiamin diphosphate [Vyazmensky96], Mg2+ [Vyazmensky96], FAD [Vyazmensky96]

Inhibitors (Unknown Mechanism): L-valine [Gollop89, Comment 1] , L-leucine [Gollop83]

Kinetic Parameters:

Substrate
Km (μM)
Citations
pyruvate
7600.0
[De78]


Sequence Features

Feature Class Location Citations Comment
Amino-Acid-Sites-That-Bind 51
[UniProt10]
UniProt: Thiamine pyrophosphate; Non-Experimental Qualifier: by similarity;
Amino-Acid-Sites-That-Bind 153
[UniProt10]
UniProt: FAD; Non-Experimental Qualifier: by similarity;
Sequence-Conflict 202 -> 203
[Ayala91, Squires83, UniProt10a]
Alternate sequence: SV; UniProt: (in Ref. 1; CAA25755 and 5; CAA38854);
Sequence-Conflict 206
[Ayala91, Squires83, UniProt10a]
Alternate sequence: V; UniProt: (in Ref. 1; CAA25755 and 5; CAA38854);
Sequence-Conflict 254
[Ayala91, Squires83, UniProt10a]
Alternate sequence: V; UniProt: (in Ref. 1; CAA25755 and 5; CAA38854);
Nucleotide-Phosphate-Binding-Region 261 -> 282
[UniProt10]
UniProt: FAD; Non-Experimental Qualifier: by similarity;
Nucleotide-Phosphate-Binding-Region 304 -> 323
[UniProt10]
UniProt: FAD; Non-Experimental Qualifier: by similarity;
Protein-Segment 397 -> 477
[UniProt10]
UniProt: Thiamine pyrophosphate binding; Sequence Annotation Type: region of interest;
Sequence-Conflict 422
[Ayala91, Squires83, UniProt10a]
Alternate sequence: S; UniProt: (in Ref. 1; CAA25755 and 5; CAA38854);
Sequence-Conflict 437 -> 438
[Ayala91, UniProt10a]
Alternate sequence: FA; UniProt: (in Ref. 5; CAA38854);
Metal-Binding-Site 448
[UniProt10]
UniProt: Magnesium; Non-Experimental Qualifier: by similarity;
Metal-Binding-Site 475
[UniProt10]
UniProt: Magnesium; Non-Experimental Qualifier: by similarity;
Sequence-Conflict 507 -> 509
[Ayala91, Squires83, UniProt10a]
Alternate sequence: RG; UniProt: (in Ref. 1; CAA25755 and 5; CAA38854);

History:
Socorro Gama-Castro on Fri Oct 29, 2004:
The start site of this gene was originally assigned solely on the basis of sequence considerations [Blattner97 ]. However, it was changed because Lago et al [2 ] attested that the real start site is actually located 90 bp downstream. The demonstration is based on protein sequencing.
10/20/97 Gene b0077 from Blattner lab Genbank (v. M52) entry merged into EcoCyc gene EG10500; confirmed by SwissProt match.


References

Ayala91: Ayala J.A. (1991). "Regulation of transcription at the 2-minute region of the genetic map of Escherichia coli." Data submission to EMBL/GenBank/DDBJ databases on 1991-01.

Barak87: Barak Z, Chipman DM, Gollop N (1987). "Physiological implications of the specificity of acetohydroxy acid synthase isozymes of enteric bacteria." J Bacteriol 169(8);3750-6. PMID: 3301814

Barak88: Barak Z, Calvo JM, Schloss JV (1988). "Acetolactate synthase isozyme III from Escherichia coli." Methods Enzymol 1988;166;455-8. PMID: 3071721

Blattner97: Blattner FR, Plunkett G, Bloch CA, Perna NT, Burland V, Riley M, Collado-Vides J, Glasner JD, Rode CK, Mayhew GF, Gregor J, Davis NW, Kirkpatrick HA, Goeden MA, Rose DJ, Mau B, Shao Y (1997). "The complete genome sequence of Escherichia coli K-12." Science 277(5331);1453-74. PMID: 9278503

De74: De Felice M, Guardiola J, Esposito B, Iaccarino M (1974). "Structural genes for a newly recognized acetolactate synthase in Escherichia coli K-12." J Bacteriol 120(3);1068-77. PMID: 4612003

De78: De Felice M, Squires C, Levinthal M (1978). "A comparative study of the acetohydroxy acid synthase isoenzymes of Escherichia coli K-12." Biochim. Biophys. Acta 541;9-17.

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

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."

Gollop83: Gollop N, Chipman DM, Barak Z (1983). "Inhibition of acetohydroxy acid synthase by leucine." Biochim Biophys Acta 1983;748(1);34-9. PMID: 6351926

Gollop89: Gollop N, Damri B, Barak Z, Chipman DM (1989). "Kinetics and mechanism of acetohydroxy acid synthase isozyme III from Escherichia coli." Biochemistry 28(15);6310-7. PMID: 2675968

Haughn85: Haughn GW, Squires CH, De Felice M, Largo CT, Calvo JM (1985). "Unusual organization of the ilvIH promoter of Escherichia coli." J Bacteriol 1985;163(1);186-98. PMID: 3891724

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

Neidhardt96: Neidhardt FC, Curtiss III R, Ingraham JL, Lin ECC, Low Jr KB, Magasanik B, Reznikoff WS, Riley M, Schaechter M, Umbarger HE "Escherichia coli and Salmonella, Cellular and Molecular Biology, Second Edition." American Society for Microbiology, Washington, D.C., 1996.

Squires83: Squires CH, De Felice M, Devereux J, Calvo JM (1983). "Molecular structure of ilvIH and its evolutionary relationship to ilvG in Escherichia coli K12." Nucleic Acids Res 1983;11(15);5299-313. PMID: 6308579

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.

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

UniProtGOA12: UniProt-GOA (2012). "Gene Ontology annotation based on UniPathway vocabulary mapping."

Vyazmensky09: Vyazmensky M, Zherdev Y, Slutzker A, Belenky I, Kryukov O, Barak Z, Chipman DM (2009). "Interactions between large and small subunits of different acetohydroxyacid synthase isozymes of Escherichia coli." Biochemistry 48(36);8731-7. PMID: 19653643

Vyazmensky96: Vyazmensky M, Sella C, Barak Z, Chipman DM (1996). "Isolation and characterization of subunits of acetohydroxy acid synthase isozyme III and reconstitution of the holoenzyme." Biochemistry 35(32);10339-46. PMID: 8756689

Weinstock92: Weinstock O, Sella C, Chipman DM, Barak Z (1992). "Properties of subcloned subunits of bacterial acetohydroxy acid synthases." J Bacteriol 1992;174(17);5560-6. PMID: 1512191

Zhao13a: Zhao Y, Niu C, Wen X, Xi Z (2013). "The minimum activation peptide from ilvH can activate the catalytic subunit of AHAS from different species." Chembiochem 14(6);746-52. PMID: 23512804


Report Errors or Provide Feedback
Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 42:D459-D471 2014
Page generated by SRI International Pathway Tools version 18.5 on Sun Nov 23, 2014, BIOCYC13A.