|Gene:||lpxT||Accession Numbers: G7146 (EcoCyc), b2174, ECK2168|
LpxT is responsible for transfer of a phosphate group from undecaprenyl-pyrophosphate to the position 1 phosphate of approximately one-third of lipid A molecules to create lipid A 1-diphosphate. LpxT is one of four Und-PP pyrophosphatases in E. coli along with BacA, YbjG, and PgpB. Und-P acts as a carrier for glycan intermediates of carbohydrate polymers such as peptidoglycan, teichoic acids, enterobacterial common antigen, and O antigen. Und-PP must be converted to Und-P by an Und-PP pyrophosphatase in order to be used and reused for attachment of these glycan intermediates.
In vitro assays show LpxT transfers a phosphate from Und-PP to Kdo2-lipid A [Touze08]. Bacitracin inhibited this reaction by sequestering Und-PP in vivo [Touze08]. Activation of the BasSR two-component system by Fe3+ results in the post-translational inhibition of LpxT-dependent lipid A modification [Herrera10].
lpxT mutants do not produce lipid A 1-diphosphate [Touze08]. The LpxT gene product appears to have a low level of undecaprenyl pyrophosphate (C55PP) phosphatase activity [El05]. Simultaneous inactivation of three genes encoding C55PP phosphatases, pgpB, bacA, and ybjG, is lethal [El05]. Depletion of BacA in the triple mutant strain causes changes in cell morphology and lysis [El05]. Overexpression of lpxT, pgpB, bacA, and ybjG leads to increased C55PP phosphatase activity in crude membrane extracts [El05]. Expression of C55PP phosphatase activity from any one of the three genes pgpB, bacA and ybjG appears to be sufficient for synthesis of undecaprenyl phosphate and survival, while expression of lpxT alone does not appear to be sufficient [El05]. bacA lpxT and bacA lpxT ybjG mutants have reduced survival in response to the inhibition of Und-PP synthesis by fosmidomycin [Tatar07]. A waaL bacA lpxT ybjG quadruple deletion mutant of W3110 expressing wbbL for O16 antigen production had increased levels of O16 attached to Und-PP resulting in a growth defect due to severely decreased availability of Und-P from recycling of Und-PP [Tatar07].
Expression of lpxT is increased by exposure to sodium salicylate [Pomposiello01]. Expression of lpxT was upregulated under basic conditions during anaerobic growth, and under acidic conditions during aerobic growth [Hayes06]. Expression of lpxT is repressed in biofilms in a tnaA mutant [Lee07].
Locations: inner membrane
|Map Position: [2,266,876 -> 2,267,589] (48.86 centisomes)||Length: 714 bp / 237 aa|
Molecular Weight of Polypeptide: 26.759 kD (from nucleotide sequence)
Unification Links: ASAP:ABE-0007196 , EchoBASE:EB3828 , EcoGene:EG14075 , EcoliWiki:b2174 , ModBase:P76445 , OU-Microarray:b2174 , PortEco:lpxT , Protein Model Portal:P76445 , RefSeq:NP_416679 , RegulonDB:G7146 , String:511145.b2174 , UniProt:P76445
In Paralogous Gene Group: 211 (2 members)
|Biological Process:||GO:0008152 - metabolic process
GO:0043165 - Gram-negative-bacterium-type cell outer membrane assembly [Touze08]
GO:0006810 - transport [UniProtGOA11]
|Molecular Function:||GO:0016776 - phosphotransferase activity, phosphate group as acceptor
GO:0050380 - undecaprenyl-diphosphatase activity [Touze08]
GO:0003824 - catalytic activity [GOA01]
|Cellular Component:||GO:0005886 - plasma membrane
[UniProtGOA11a, UniProtGOA11, DiazMejia09, Zhang07a, Daley05]
GO:0016020 - membrane [UniProtGOA11, GOA01]
GO:0016021 - integral component of membrane [UniProtGOA11]
|MultiFun Terms:||cell structure|
|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]|
Enzymatic reaction of: undecaprenyl-pyrophosphate pyrophosphatase (protein with low undecaprenyl pyrophosphate phosphatase activity)
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.
Reversibility of this reaction is unspecified.
|Feature Class||Location||Common Name||Citations||Comment|
|Transmembrane-Region||6 -> 26||LpxT TM1|
|Transmembrane-Region||63 -> 83|
|Transmembrane-Region||63 -> 82||LpxT TM2|
|Transmembrane-Region||91 -> 111||LpxT TM3|
|Active-Site||194, 183, 184, 190, 150, 149, 148, 147, 124, 123, 116||acid phosphatase catalytic site|
|Transmembrane-Region||146 -> 166||LpxT TM4|
|Transmembrane-Region||168 -> 188|
|Transmembrane-Region||170 -> 189||LpxT TM5|
|Transmembrane-Region||195 -> 215||LpxT TM6|
Peter D. Karp on Thu Jan 16, 2003:
Predicted gene function revised as a result of E. coli genome reannotation by Serres et al. [Serres01 ].
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
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
El05: El Ghachi M, Derbise A, Bouhss A, Mengin-Lecreulx D (2005). "Identification of multiple genes encoding membrane proteins with undecaprenyl pyrophosphate phosphatase (UppP) activity in Escherichia coli." J Biol Chem 280(19);18689-95. PMID: 15778224
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
Hayes06: Hayes ET, Wilks JC, Sanfilippo P, Yohannes E, Tate DP, Jones BD, Radmacher MD, BonDurant SS, Slonczewski JL (2006). "Oxygen limitation modulates pH regulation of catabolism and hydrogenases, multidrug transporters, and envelope composition in Escherichia coli K-12." BMC Microbiol 6;89. PMID: 17026754
Herrera10: Herrera CM, Hankins JV, Trent MS (2010). "Activation of PmrA inhibits LpxT-dependent phosphorylation of lipid A promoting resistance to antimicrobial peptides." Mol Microbiol 76(6);1444-60. PMID: 20384697
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
Pomposiello01: Pomposiello PJ, Bennik MH, Demple B (2001). "Genome-wide transcriptional profiling of the Escherichia coli responses to superoxide stress and sodium salicylate." J Bacteriol 183(13);3890-902. PMID: 11395452
Tatar07: Tatar LD, Marolda CL, Polischuk AN, van Leeuwen D, Valvano MA (2007). "An Escherichia coli undecaprenyl-pyrophosphate phosphatase implicated in undecaprenyl phosphate recycling." Microbiology 153(Pt 8);2518-29. PMID: 17660416
Touze08: Touze T, Tran AX, Hankins JV, Mengin-Lecreulx D, Trent MS (2008). "Periplasmic phosphorylation of lipid A is linked to the synthesis of undecaprenyl phosphate." Mol Microbiol 67(2);264-77. PMID: 18047581
Zhang07a: Zhang N, Chen R, Young N, Wishart D, Winter P, Weiner JH, Li L (2007). "Comparison of SDS- and methanol-assisted protein solubilization and digestion methods for Escherichia coli membrane proteome analysis by 2-D LC-MS/MS." Proteomics 7(4);484-93. PMID: 17309111
Gogol11: Gogol EB, Rhodius VA, Papenfort K, Vogel J, Gross CA (2011). "Small RNAs endow a transcriptional activator with essential repressor functions for single-tier control of a global stress regulon." Proc Natl Acad Sci U S A 108(31);12875-80. PMID: 21768388
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