Escherichia coli K-12 substr. MG1655 Enzyme: low-specificity L-threonine aldolase

Gene: ltaE Accession Numbers: G6455 (EcoCyc), b0870, ECK0861

Synonyms: ltaA, ybjU

Regulation Summary Diagram: ?

Regulation summary diagram for ltaE

Subunit composition of low-specificity L-threonine aldolase = [LtaE]4

The low-specificity L-threonine aldolase (LtaE) can act on both L-threonine and L-allo-threonine as well as L-threo-phenylserine and L-erythro-phenylserine, but does not utilize the D isomers. The enzyme requires pyridoxal phosphate as a cofactor. L-threonine aldolase may serve in an alternative pathway for glycine biosynthesis when the major pathway is disrupted by a mutation in glyA [Liu98].

LtaE was found to be part of a serendipitous metabolic pathway that produces an intermediate of the pyridoxal 5'-phosphate biosynthesis I pathway, 4-phospho-hydroxy-L-threonine, that lies downstream of PdxB. The pathway diverts 3-phosphohydroxypyruvate from serine biosynthesis. Here, LtaE catalyzes the aldol condensation of glycolaldehyde and glycine to form 4-hydroxy-L-threonine [Kim10c].

An ltaE mutant has no growth defect when grown on glucose as the sole source of carbon [Liu98].

LtaE: "low-specificity L-threonine aldolase" [Liu98]

Locations: cytosol

Map Position: [907,516 <- 908,517] (19.56 centisomes, 70°)
Length: 1002 bp / 333 aa

Molecular Weight of Polypeptide: 36.495 kD (from nucleotide sequence), 36.5 kD (experimental) [Liu98 ]

Molecular Weight of Multimer: 140 kD (experimental) [Liu98]

Unification Links: ASAP:ABE-0002954 , EchoBASE:EB3454 , EcoGene:EG13690 , EcoliWiki:b0870 , ModBase:P75823 , OU-Microarray:b0870 , PortEco:ltaE , PR:PRO_000023135 , Pride:P75823 , Protein Model Portal:P75823 , RefSeq:NP_415391 , RegulonDB:G6455 , SMR:P75823 , String:511145.b0870 , Swiss-Model:P75823 , UniProt:P75823

Relationship Links: InterPro:IN-FAMILY:IPR001597 , InterPro:IN-FAMILY:IPR015421 , InterPro:IN-FAMILY:IPR015422 , InterPro:IN-FAMILY:IPR015424 , InterPro:IN-FAMILY:IPR023603 , Pfam:IN-FAMILY:PF01212

Gene-Reaction Schematic: ?

Gene-Reaction Schematic

Instance reaction of [DL-allothreonine ↔ acetaldehyde + glycine] (4.1.2.-):
i1: L-allo-threonine ↔ glycine + acetaldehyde (

Genetic Regulation Schematic: ?

Genetic regulation schematic for ltaE

GO Terms:

Biological Process: GO:0006545 - glycine biosynthetic process Inferred from experiment [Liu98]
GO:0006520 - cellular amino acid metabolic process Inferred by computational analysis [GOA01]
GO:0006567 - threonine catabolic process Inferred by computational analysis [Gaudet10]
Molecular Function: GO:0008732 - L-allo-threonine aldolase activity Inferred from experiment [Liu98]
GO:0030170 - pyridoxal phosphate binding Inferred from experiment Inferred by computational analysis [GOA01, Liu98]
GO:0042802 - identical protein binding Inferred from experiment [diSalvo14, Liu98]
GO:0050179 - phenylserine aldolase activity Inferred from experiment [Liu98]
GO:0003824 - catalytic activity Inferred by computational analysis [GOA01]
GO:0016829 - lyase activity Inferred by computational analysis [UniProtGOA11, GOA01]
Cellular Component: GO:0005829 - cytosol Inferred from experiment Inferred by computational analysis [Gaudet10, DiazMejia09, Ishihama08]
GO:0005737 - cytoplasm

MultiFun Terms: metabolism biosynthesis of building blocks amino acids glycine

Essentiality data for ltaE 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]

Curated 07-Dec-2010 by Keseler I , SRI International
Last-Curated ? 17-Nov-2011 by Fulcher C , SRI International

Enzymatic reaction of: 4-hydroxy-L-threonine aldolase (low-specificity L-threonine aldolase)

EC Number: 4.1.2.-

4-hydroxy-L-threonine <=> glycolaldehyde + glycine

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the direction of enzyme catalysis.

This reaction is reversible. [Kim10c]

Alternative Substrates for 4-hydroxy-L-threonine: 4-hydroxy-L-allo-threonine [Kim10c ]

In the reverse aldol condensation reaction the enzyme produces 4-hydroxy-L-threonine and 4-hydroxy-L-allo-threonine in a ratio of 1.0:0.7 [Kim10c].

Cofactors or Prosthetic Groups: pyridoxal 5'-phosphate

Kinetic Parameters:

Km (μM)

Enzymatic reaction of: threonine aldolase

EC Number:

L-threonine <=> acetaldehyde + glycine

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: superpathway of L-threonine metabolism , L-threonine degradation IV

Cofactors or Prosthetic Groups: pyridoxal 5'-phosphate [Liu98]

Kinetic Parameters:

Km (μM)

T(opt): 65-70 °C [Liu98]

pH(opt): 8.5-9 [Liu98]

Enzymatic reaction of: phenylserine aldolase (low-specificity L-threonine aldolase)

EC Number:

L-threo-3-phenylserine <=> benzaldehyde + glycine

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

Reversibility of this reaction is unspecified.

Alternative Substrates for L-threo-3-phenylserine: L-serine [Contestabile01 ]

Cofactors or Prosthetic Groups: pyridoxal 5'-phosphate [Liu98]

Activators (Unknown Mechanism): L-erythro-3-phenylserine [Liu98]

Kinetic Parameters:

Km (μM)

Enzymatic reaction of: L-allo-threonine aldolase (low-specificity L-threonine aldolase)

Synonyms: L-allo-TA, L-allo-threonine acetaldehyde-lyase

EC Number:

L-allo-threonine <=> glycine + acetaldehyde

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the direction of enzyme catalysis.

This reaction is reversible.

Cofactors or Prosthetic Groups: pyridoxal 5'-phosphate [Comment 5, Liu98]

Kinetic Parameters:

Km (μM)

pH(opt): 7.0 [Contestabile01]

Sequence Features

Protein sequence of LtaE with features indicated

Feature Class Location Citations Comment
N6-pyridoxal-phosphate-Lys-Modification 197
UniProt: N6-(pyridoxal phosphate)lysine; Non-Experimental Qualifier: by similarity.

Gene Local Context (not to scale): ?

Gene local context diagram

Transcription Units:

Transcription-unit diagram

Transcription-unit diagram

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

Contestabile01: Contestabile R, Paiardini A, Pascarella S, di Salvo ML, D'Aguanno S, Bossa F (2001). "l-Threonine aldolase, serine hydroxymethyltransferase and fungal alanine racemase. A subgroup of strictly related enzymes specialized for different functions." Eur J Biochem 268(24);6508-25. PMID: 11737206

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

diSalvo14: di Salvo ML, Remesh SG, Vivoli M, Ghatge MS, Paiardini A, D'Aguanno S, Safo MK, Contestabile R (2014). "On the catalytic mechanism and stereospecificity of Escherichia coli l-threonine aldolase." FEBS J 281(1);129-45. PMID: 24165453

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

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

GOA01: 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

Kim10c: Kim J, Kershner JP, Novikov Y, Shoemaker RK, Copley SD (2010). "Three serendipitous pathways in E. coli can bypass a block in pyridoxal-5'-phosphate synthesis." Mol Syst Biol 6;436. PMID: 21119630

Liu98: Liu JQ, Dairi T, Itoh N, Kataoka M, Shimizu S, Yamada H (1998). "Gene cloning, biochemical characterization and physiological role of a thermostable low-specificity L-threonine aldolase from Escherichia coli." Eur J Biochem 1998;255(1);220-6. PMID: 9692922

UniProt11: UniProt Consortium (2011). "UniProt version 2011-11 released on 2011-11-22 00:00:00." Database.

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

Other References Related to Gene Regulation

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

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Please cite the following article in publications resulting from the use of EcoCyc: Nucleic Acids Research 41:D605-12 2013
Page generated by SRI International Pathway Tools version 19.0 on Tue Oct 6, 2015, biocyc13.