If an enzyme name is shown in bold, there is experimental evidence for this enzymatic activity.
Locations of Mapped Genes:
|Superclasses:||Biosynthesis → Amino Acids Biosynthesis → Individual Amino Acids Biosynthesis → Other Amino Acid Biosynthesis|
The homoserine biosynthesis pathway is a three-step pathway that converts L-aspartate into homoserine. Two of the three enzymes that catalyze the first step in this pathway are bifunctional, also serving to catalyze the final step in the pathway.
The final product of this pathway, homoserine, feeds into biosynthetic pathways for both threonine and methionine. Fittingly, this pathway is regulated by the outputs of both of those pathways. metL is repressed by abundant methionine. thrA is regulated by threonine- and isoleucine-dependent attenuation, and both the aspartate kinase and homoserine dehydrogenase activities of ThrA are inhibited by threonine. The middle enzymatic activity, aspartate semialdehyde dehydrogenase, is subject to some form of repression by both methionine and threonine.
Review: Patte, J.-C., Biosynthesis of Threonine and Lysine, Chapter 32 [Neidhardt96]
Superpathways: aspartate superpathway , superpathway of lysine, threonine and methionine biosynthesis I , threonine biosynthesis , homoserine and methionine biosynthesis , superpathway of S-adenosyl-L-methionine biosynthesis
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.
Alvarez04: Alvarez E, Ramon F, Magan C, Diez E (2004). "L-cystine inhibits aspartate-beta-semialdehyde dehydrogenase by covalently binding to the essential 135Cys of the enzyme." Biochim Biophys Acta 1696(1);23-9. PMID: 14726201
Angeles89: Angeles TS, Smanik PA, Borders CL, Viola RE (1989). "Aspartokinase-homoserine dehydrogenase I from Escherichia coli: pH and chemical modification studies of the kinase activity." Biochemistry 28(22);8771-7. PMID: 2557908
Angeles90: Angeles TS, Viola RE (1990). "The kinetic mechanisms of the bifunctional enzyme aspartokinase-homoserine dehydrogenase I from Escherichia coli." Arch Biochem Biophys 283(1);96-101. PMID: 2241177
Bearer78: Bearer CF, Neet KE (1978). "Threonine inhibition of the aspartokinase--homoserine dehydrogenase I of Escherichia coli. A slow transient and cooperativity of inhibition of the aspartokinase activity." Biochemistry 1978;17(17);3523-30. PMID: 28752
Bearer78a: Bearer CF, Neet KE (1978). "Threonine inhibition of the aspartokinase--homoserine dehydrogenase I of Escherichia coli. Stopped-flow kinetics and the cooperativity of inhibition of the homoserine dehydrogenase activity." Biochemistry 17(17);3517-22. PMID: 28751
Belfaiza84: Belfaiza J, Fazel A, Muller K, Cohen GN (1984). "E. coli aspartokinase II-homoserine dehydrogenase II polypeptide chain has a triglobular structure." Biochem Biophys Res Commun 123(1);16-20. PMID: 6383377
Biellmann80: Biellmann JF, Eid P, Hirth C, Jornvall H (1980). "Aspartate-beta-semialdehyde dehydrogenase from Escherichia coli. Purification and general properties." Eur J Biochem 1980;104(1);53-8. PMID: 6102909
Biellmann80a: Biellmann JF, Eid P, Hirth C (1980). "Affinity labeling of the Escherichia coli aspartate-beta-semialdehyde dehydrogenase with an alkylating coenzyme analogue. Half-site reactivity and competition with the substrate alkylating analogue." Eur J Biochem 1980;104(1);65-9. PMID: 6102911
Broglie83: Broglie KE, Takahashi M (1983). "Fluorescence studies of threonine-promoted conformational transitions in aspartokinase I using the substrate analogue 2'(3')-O-(2,4,6-trinitrophenyl)adenosine 5'-triphosphate." J Biol Chem 1983;258(21);12940-6. PMID: 6313682
Cassan75: Cassan M, Boy E, Borne F, Patte JC (1975). "Regulation of the lysine biosynthetic pathway in Escherichia coli K-12: isolation of a cis-dominant constitutive mutant for AK III synthesis." J Bacteriol 123(2);391-9. PMID: 238953
Cassan86: Cassan M, Parsot C, Cohen GN, Patte JC (1986). "Nucleotide sequence of lysC gene encoding the lysine-sensitive aspartokinase III of Escherichia coli K12. Evolutionary pathway leading to three isofunctional enzymes." J Biol Chem 1986;261(3);1052-7. PMID: 3003049
Clark72: Clark RB, Ogilvie JW (1972). "Aspartokinase I-homoserine dehydrogenase I of Escherichia coli K12 .Subunit molecular weight and nicotinamide-adenine dinucleotide phosphate binding." Biochemistry 11(7);1278-82. PMID: 4401168
CossartGheerbra78: Cossart-Gheerbrant P, Sibilli-Weill L, Briley PA, Chalvignac MA, Le Bras G, Cohen GN (1978). "The primary structure of Escherichia coli K12 aspartokinase I-homoserine dehydrogenase I-Isolation and characterisation of the peptides produced by cyanogen bromide." Biochim Biophys Acta 535(2);206-15. PMID: 354697
Costrejean77: Costrejean JM, Truffa-Bachi P (1977). "Threonine-sensitive homoserine dehydrogenase and aspartokinase activities of Escherichia coli K12. Kinetic and spectroscopic effects upon binding of serine and threonine." J Biol Chem 252(15);5332-6. PMID: 328500
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