|Gene:||metA||Accession Numbers: EG10581 (EcoCyc), b4013, ECK4005|
Homoserine O-succinyltransferase (MetA) catalyzes the first unique step in the de novo methionine biosynthesis pathway in Escherichia coli (see pathway L-methionine biosynthesis I). It transfers a succinyl group from succinyl-CoA to homoserine. It is regulated at several levels and it appears to have a role in regulating bacterial growth. Its activity is regulated through allosteric feedback inhibition by the pathway end product methionine and also synergistically by the methionine derivative S-adenosylmethionine [Born99] (see pathway S-adenosyl-L-methionine cycle I). Expression of the enzyme is negatively regulated at the transcriptional level by the methionine regulon repressor MetJ and positively regulated by the activator MetR. MetA has also been shown to be a heat shock protein [Ron90, Biran95]. It was found to be very thermolabile, undergoing aggregation and proteolysis at elevated temperatures [Biran00, Gur02, Mordukhova08]. It appears to be regulated by temperature-dependent proteolysis, thereby mediating a change in growth rate as a function of temperature [Katz09].
Review: Hondrop, E.R. and R.G. Matthews (2006) "Methionine" EcoSal 22.214.171.124 [ECOSAL] .
The gene encoding this enzyme has been cloned, overexpressed, and its protein product characterized [Born99]. Site-directed mutagenesis and steady-state kinetic studies identified amino acid residues important to its catalytic mechanism [Rosen04, Ziegler07, Coe07] . Because this enzyme is not found in humans, it is of interest in the design of antimicrobials [Coe07]. The crystal structure of the orthologous MetA from Bacillus cereus in complex with homoserine has been determined at 2.0 Å resolution [Zubieta08].
The apparent molecular mass of the subunit was determined by SDS-PAGE and the apparent molecular mass of the native enzyme was determined by gel filtration chromatography [Born99].
Gene Citations: [Old93]
|Map Position: [4,212,303 -> 4,213,232] (90.79 centisomes, 327°)||Length: 930 bp / 309 aa|
Molecular Weight of Polypeptide: 35.727 kD (from nucleotide sequence), 35.6 kD (experimental) [Born99 ]
Molecular Weight of Multimer: 86.0 kD (experimental) [Born99]
Unification Links: ASAP:ABE-0013121 , CGSC:516 , EchoBASE:EB0576 , EcoGene:EG10581 , EcoliWiki:b4013 , Mint:MINT-1343536 , ModBase:P07623 , OU-Microarray:b4013 , PortEco:metA , PR:PRO_000023208 , Pride:P07623 , Protein Model Portal:P07623 , RefSeq:NP_418437 , RegulonDB:EG10581 , SMR:P07623 , String:511145.b4013 , Swiss-Model:P07623 , UniProt:P07623
|Biological Process:||GO:0008152 - metabolic process
GO:0008652 - cellular amino acid biosynthetic process [UniProtGOA11a]
GO:0009086 - methionine biosynthetic process [UniProtGOA11a]
GO:0019281 - L-methionine biosynthetic process from homoserine via O-succinyl-L-homoserine and cystathionine [GOA06, GOA01a]
|Molecular Function:||GO:0008899 - homoserine O-succinyltransferase activity
[GOA06, GOA01, GOA01a, Born99]
GO:0042803 - protein homodimerization activity [Born99]
GO:0003824 - catalytic activity [UniProtGOA11a]
GO:0016740 - transferase activity [UniProtGOA11a]
GO:0016746 - transferase activity, transferring acyl groups [UniProtGOA11a]
|Cellular Component:||GO:0005737 - cytoplasm
[UniProtGOA11, UniProtGOA11a, GOA06, GOA01a]
GO:0005829 - cytosol [DiazMejia09]
|MultiFun Terms:||metabolism → biosynthesis of building blocks → amino acids → methionine|
|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 0.4% glucose||No||37||Aerobic||7.2||0.27||No [Patrick07, Comment 3]|
|M9 medium with 1% glycerol||No||37||Aerobic||7.2||0.35||No [Joyce06]|
|MOPS medium with 0.4% glucose||Indeterminate||37||Aerobic||7.2||0.22||Yes [Baba06, Comment 2] |
No [Feist07, Comment 4]
Enzymatic reaction of: homoserine O-succinyltransferase
Synonyms: homoserine O-transsuccinylase, succinyl-CoA:L-homoserine O-succinyltransferase, homoserine succinyltransferase, O-succinylhomoserine synthetase, HTS
EC Number: 126.96.36.199
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 S-adenosyl-L-methionine biosynthesis , L-homoserine and L-methionine biosynthesis , superpathway of L-lysine, L-threonine and L-methionine biosynthesis I , aspartate superpathway , L-methionine biosynthesis I
The enzyme employs a ping-pong mechanism in which the succinyl group of succinyl-CoA is first transferred to the enzyme, forming a succinyl-enzyme intermediate, and then transferred to homoserine to form the product O-succinylhomoserine. The equilibrium constant for the reaction strongly favored production of O-succinylhomoserine from succinyl-CoA [Born99].
|Chain||2 -> 309|
|Active-Site||47, 142, 235|
10/20/97 Gene b4013 from Blattner lab Genbank (v. M52) entry merged into EcoCyc gene EG10581; 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
Born99: Born TL, Blanchard JS (1999). "Enzyme-catalyzed acylation of homoserine: mechanistic characterization of the Escherichia coli metA-encoded homoserine transsuccinylase." Biochemistry 1999;38(43);14416-23. PMID: 10572016
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
Duclos89: Duclos B, Cortay JC, Bleicher F, Ron EZ, Richaud C, Saint Girons I, Cozzone AJ (1989). "Nucleotide sequence of the metA gene encoding homoserine trans-succinylase in Escherichia coli." Nucleic Acids Res 17(7);2856. PMID: 2654885
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
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
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
Katz09: Katz C, Rasouly A, Gur E, Shenhar Y, Biran D, Ron EZ (2009). "Temperature-dependent proteolysis as a control element in Escherichia coli metabolism." Res Microbiol 160(9);684-6. PMID: 19770038
Mordukhova08: Mordukhova EA, Lee HS, Pan JG (2008). "Improved thermostability and acetic acid tolerance of Escherichia coli via directed evolution of homoserine o-succinyltransferase." Appl Environ Microbiol 74(24);7660-8. PMID: 18978085
Ron90: Ron EZ, Alajem S, Biran D, Grossman N (1990). "Adaptation of Escherichia coli to elevated temperatures: the metA gene product is a heat shock protein." Antonie Van Leeuwenhoek 1990;58(3);169-74. PMID: 2256677
Ziegler07: Ziegler K, Noble SM, Mutumanje E, Bishop B, Huddler DP, Born TL (2007). "Identification of catalytic cysteine, histidine, and lysine residues in Escherichia coli homoserine transsuccinylase." Biochemistry 46(10);2674-83. PMID: 17302437
Zubieta08: Zubieta C, Arkus KA, Cahoon RE, Jez JM (2008). "A single amino acid change is responsible for evolution of acyltransferase specificity in bacterial methionine biosynthesis." J Biol Chem 283(12);7561-7. PMID: 18216013
Marincs06: Marincs F, Manfield IW, Stead JA, McDowall KJ, Stockley PG (2006). "Transcript analysis reveals an extended regulon and the importance of protein-protein co-operativity for the Escherichia coli methionine repressor." Biochem J 396(2);227-34. PMID: 16515535
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