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Escherichia coli K-12 substr. MG1655 Enzyme: myristoyl-acyl carrier protein (ACP)-dependent acyltransferase



Gene: lpxM Accession Numbers: EG10614 (EcoCyc), b1855, ECK1856

Synonyms: mlt, waaN, msbB

Regulation Summary Diagram: ?

Summary:
Myristoyl-acyl carrier protein (ACP)-dependent acyltransferase (LpxM) catalyzes the transfer of myristate from myristoyl-ACP to the 3'-R-3-hydroxymyristoyl chain of KDO2-(lauroyl)-lipid IVA. This is one of the last two acylation reactions needed to synthesize KDO2-lipid A. LpxM functions optimally after laurate incorporation by LpxL has taken place [Clementz97]. LpxM shares sequence homology and functional similarity to LpxL [Karow92].

Mutants of lpxM, are characterized by attenuated cytokine induction and with an LPS that lacked the myristoyl fatty acid moiety of the lipid A [Somerville96]. Overexpression of lpxM (msbB) suppresses the temperature sensitive growth associated with mutations in the lpxL gene. Mutations in lpxM have caused reduced acylation of LPS, resulting in constitutive expression of the sigma(E) regulon above wild-type levels [Tam05]. Strains overexpressing LpxM and with a deleted kdtA, the gene encoding the KDO transferase, accumulated pentaacylated lipid A [Reynolds09].

Mutational analysis has shown that the lpxM gene is not essential for growth [Karow92].

When E. coli cells are subjected to cold shock or grown at low temperatures, palmitoleate is incorporated into lipid A instead of laurate. Myristoyl acyltransferase accepts either substrate. [Clementz97, Clementz96, Carty99]

Locations: cell wall, inner membrane

Map Position: [1,937,246 <- 1,938,217] (41.75 centisomes)
Length: 972 bp / 323 aa

Molecular Weight of Polypeptide: 37.41 kD (from nucleotide sequence)

Unification Links: ASAP:ABE-0006185 , CGSC:32359 , DIP:DIP-10262N , EchoBASE:EB0609 , EcoGene:EG10614 , EcoliWiki:b1855 , Mint:MINT-1309336 , OU-Microarray:b1855 , PortEco:lpxM , PR:PRO_000023295 , Pride:P24205 , Protein Model Portal:P24205 , RefSeq:NP_416369 , RegulonDB:EG10614 , String:511145.b1855 , UniProt:P24205

Relationship Links: InterPro:IN-FAMILY:IPR004960 , InterPro:IN-FAMILY:IPR011921 , Pfam:IN-FAMILY:PF03279

Gene-Reaction Schematic: ?

GO Terms:

Biological Process: GO:0036104 - Kdo2-lipid A biosynthetic process Inferred from experiment Inferred by computational analysis [UniProtGOA12, Clementz97]
GO:0009103 - lipopolysaccharide biosynthetic process Inferred by computational analysis [UniProtGOA12, UniProtGOA11a, GOA01a]
GO:0009244 - lipopolysaccharide core region biosynthetic process Inferred by computational analysis [GOA01a]
Molecular Function: GO:0016747 - transferase activity, transferring acyl groups other than amino-acyl groups Inferred from experiment Inferred by computational analysis [GOA01a, Clementz97]
GO:0016740 - transferase activity Inferred by computational analysis [UniProtGOA11a]
GO:0016746 - transferase activity, transferring acyl groups Inferred by computational analysis [UniProtGOA11a, GOA01a]
Cellular Component: GO:0005886 - plasma membrane Inferred by computational analysis [UniProtGOA11, UniProtGOA11a, DiazMejia09]
GO:0009276 - Gram-negative-bacterium-type cell wall Inferred by computational analysis [GOA01a]
GO:0016020 - membrane Inferred by computational analysis [UniProtGOA11a]
GO:0016021 - integral component of membrane Inferred by computational analysis [UniProtGOA11a, GOA01a]

MultiFun Terms: cell structure membrane
cell structure surface antigens (ECA, O antigen of LPS)
metabolism biosynthesis of macromolecules (cellular constituents) lipopolysaccharide lipid A

Essentiality data for lpxM 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]

Credits:
Last-Curated ? 29-Jul-2013 by Kubo A , SRI International


Enzymatic reaction of: myristoyl-acyl carrier protein (ACP)-dependent acyltransferase

Synonyms: myristoyl transferase, myristoyl acyltransferase

EC Number: 2.3.1.-

a myristoyl-[acp] + KDO2-(palmitoleoyl)-lipid IVA <=> (KDO)2-lipid A, cold adapted + a holo-[acyl-carrier protein]

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.

The reaction is favored in the direction shown.

EC Number: 2.3.1.-

a myristoyl-[acp] + (KDO)2-(lauroyl)-lipid IVA <=> (KDO)2-lipid A + a holo-[acyl-carrier protein]

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.

The reaction is favored in the direction shown.

In Pathways: superpathway of lipopolysaccharide biosynthesis , (KDO)2-lipid A biosynthesis I , superpathway of (KDO)2-lipid A biosynthesis

Summary:
Under normal growth conditions myristoyl acyltransferase incorporates a myristate residue into KDO2-(lauroyl)-lipid IVA. This is one of the last two acylation reactions needed to synthesize KDO2-lipid A.

When E. coli cells are subjected to cold shock or grown at low temperatures, palmitoleate is incorporated into lipid A instead of laurate. Myristoyl acyltransferase accepts either substrate. [Clementz97, Clementz96, Carty99]


Sequence Features

Feature Class Location Citations Comment
Transmembrane-Region 23 -> 43
[UniProt10a]
UniProt: Helical;; Non-Experimental Qualifier: potential;


Gene Local Context (not to scale): ?

Transcription Unit:

Notes:

History:
10/20/97 Gene b1855 from Blattner lab Genbank (v. M52) entry merged into EcoCyc gene EG10614; confirmed by SwissProt match.


References

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

Carty99: Carty SM, Sreekumar KR, Raetz CR (1999). "Effect of cold shock on lipid A biosynthesis in Escherichia coli. Induction At 12 degrees C of an acyltransferase specific for palmitoleoyl-acyl carrier protein." J Biol Chem 1999;274(14);9677-85. PMID: 10092655

Clementz96: Clementz T, Bednarski JJ, Raetz CR (1996). "Function of the htrB high temperature requirement gene of Escherchia coli in the acylation of lipid A: HtrB catalyzed incorporation of laurate." J Biol Chem 1996;271(20);12095-102. PMID: 8662613

Clementz97: Clementz T, Zhou Z, Raetz CR (1997). "Function of the Escherichia coli msbB gene, a multicopy suppressor of htrB knockouts, in the acylation of lipid A. Acylation by MsbB follows laurate incorporation by HtrB." J Biol Chem 1997;272(16);10353-60. PMID: 9099672

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

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

GOA01a: GOA, DDB, FB, MGI, ZFIN (2001). "Gene Ontology annotation through association of InterPro records with GO terms."

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

Karow92: Karow M, Georgopoulos C (1992). "Isolation and characterization of the Escherichia coli msbB gene, a multicopy suppressor of null mutations in the high-temperature requirement gene htrB." J Bacteriol 174(3);702-10. PMID: 1732206

Reynolds09: Reynolds CM, Raetz CR (2009). "Replacement of lipopolysaccharide with free lipid A molecules in Escherichia coli mutants lacking all core sugars." Biochemistry 48(40);9627-40. PMID: 19754149

Somerville96: Somerville JE, Cassiano L, Bainbridge B, Cunningham MD, Darveau RP (1996). "A novel Escherichia coli lipid A mutant that produces an antiinflammatory lipopolysaccharide." J Clin Invest 97(2);359-65. PMID: 8567955

Tam05: Tam C, Missiakas D (2005). "Changes in lipopolysaccharide structure induce the sigma(E)-dependent response of Escherichia coli." Mol Microbiol 55(5);1403-12. PMID: 15720549

UniProt10a: UniProt Consortium (2010). "UniProt version 2010-07 released on 2010-06-15 00:00:00." Database.

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

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."


Report Errors or Provide Feedback
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 18.5 on Thu Nov 27, 2014, biocyc13.