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Escherichia coli K-12 substr. MG1655 Enzyme: UDP-2,3-diacylglucosamine hydrolase



Gene: lpxH Accession Numbers: EG12666 (EcoCyc), b0524, ECK0517

Synonyms: ybbF

Regulation Summary Diagram: ?

Summary:
UDP-2,3-diacylglucosamine hydrolase (LpxH) catalyzes the fourth step in lipid A synthesis by hydrolyzing UDP-2,3-bis(3-hydroxymyristoyl)glucosamine, yielding 2,3-bis(3-hydroxymyristoyl)-β-D-glucosaminyl 1-phosphate (lipid X). It catalyzes the attack of water on the α-P atom of the UDP moiety to form lipid X and UMP. Substrate characteristics and a detailed catalytic mechanism have been described [Takayama83, Babinski02].

LpxH is a peripheral membrane protein which is stimulated by Mn2+ in vitro [Babinski02, Raetz07].

Although LpxH and CDP-diacylglycerol pyrophosphatase (Cdh) both carry out the same activity in vitro, Cdh can not substritute for LpxH in vivo [Babinski02a]. Likewise, the Cdh substrate CDP-diacylglycerol is not a substrate for LpxH [Babinski02].

LpxH is essential for growth [Babinski02a]. Although present in E. coli, LpxH is unusual in that it is missing in about one third of Gram-negative genomes [Metzger10, Raetz07].

Locations: cytosol, inner membrane

Map Position: [552,441 <- 553,163] (11.91 centisomes)
Length: 723 bp / 240 aa

Molecular Weight of Polypeptide: 26.894 kD (from nucleotide sequence)

Unification Links: ASAP:ABE-0001804 , DIP:DIP-10125N , EchoBASE:EB2532 , EcoGene:EG12666 , EcoliWiki:b0524 , ModBase:P43341 , OU-Microarray:b0524 , PortEco:lpxH , PR:PRO_000023124 , Protein Model Portal:P43341 , RefSeq:NP_415057 , RegulonDB:EG12666 , SMR:P43341 , String:511145.b0524 , UniProt:P43341

Relationship Links: InterPro:IN-FAMILY:IPR004843 , InterPro:IN-FAMILY:IPR010138 , Pfam:IN-FAMILY:PF00149

Gene-Reaction Schematic: ?

GO Terms:

Biological Process: GO:0009245 - lipid A biosynthetic process Inferred from experiment Inferred by computational analysis [UniProtGOA11, GOA01, Babinski02a, Babinski02]
GO:0006629 - lipid metabolic process Inferred by computational analysis [UniProtGOA11]
Molecular Function: GO:0008758 - UDP-2,3-diacylglucosamine hydrolase activity Inferred from experiment [Babinski02a, Babinski02]
GO:0016462 - pyrophosphatase activity Inferred by computational analysis [GOA01]
GO:0016787 - hydrolase activity Inferred by computational analysis [UniProtGOA11, GOA01]
Cellular Component: GO:0019897 - extrinsic component of plasma membrane Inferred from experiment [Babinski02a]
GO:0005737 - cytoplasm Inferred by computational analysis [UniProtGOA11a, UniProtGOA11, GOA01]
GO:0005829 - cytosol Inferred by computational analysis [DiazMejia09]

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

Essentiality data for lpxH knockouts: ?

Growth Medium Growth? T (°C) O2 pH Osm/L Growth Observations
LB Lennox No 37 Aerobic 7   No [Baba06, Comment 1]

Credits:
Curated 22-Aug-2006 by Shearer A , SRI International
Last-Curated ? 29-Jul-2013 by Kubo A , SRI International


Enzymatic reaction of: UDP-2,3-diacylglucosamine hydrolase

Synonyms: lipid X synthase

EC Number: 3.6.1.54

UDP-2,3-bis[O-(3R)-3-hydroxymyristoyl]-α-D-glucosamine + H2O <=> 2,3-bis[(3R)-3-hydroxymyristoyl]-α-D-glucosaminyl 1-phosphate + UMP + 2 H+

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 (KDO)2-lipid A biosynthesis , superpathway of lipopolysaccharide biosynthesis , lipid IVA biosynthesis

Kinetic Parameters:

Substrate
Km (μM)
Citations
UDP-2,3-bis[O-(3R)-3-hydroxymyristoyl]-α-D-glucosamine
62.0
[Babinski02]

pH(opt): 8 [Babinski02]


Gene Local Context (not to scale): ?

Transcription Unit:

Notes:

History:
10/20/97 Gene b0524 from Blattner lab Genbank (v. M52) entry merged into EcoCyc gene EG12666; 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

Babinski02: Babinski KJ, Ribeiro AA, Raetz CR (2002). "The Escherichia coli gene encoding the UDP-2,3-diacylglucosamine pyrophosphatase of lipid A biosynthesis." J Biol Chem 277(29);25937-46. PMID: 12000770

Babinski02a: Babinski KJ, Kanjilal SJ, Raetz CR (2002). "Accumulation of the lipid A precursor UDP-2,3-diacylglucosamine in an Escherichia coli mutant lacking the lpxH gene." J Biol Chem 277(29);25947-56. PMID: 12000771

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

Metzger10: Metzger LE, Raetz CR (2010). "An alternative route for UDP-diacylglucosamine hydrolysis in bacterial lipid A biosynthesis." Biochemistry 49(31);6715-26. PMID: 20608695

Raetz07: Raetz CR, Reynolds CM, Trent MS, Bishop RE (2007). "Lipid A modification systems in gram-negative bacteria." Annu Rev Biochem 76;295-329. PMID: 17362200

Takayama83: Takayama K, Qureshi N, Mascagni P, Nashed MA, Anderson L, Raetz CR (1983). "Fatty acyl derivatives of glucosamine 1-phosphate in Escherichia coli and their relation to lipid A. Complete structure of A diacyl GlcN-1-P found in a phosphatidylglycerol-deficient mutant." J Biol Chem 258(12);7379-85. PMID: 6345522

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

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


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 Wed Nov 26, 2014, biocyc13.