2.3.1.269: apolipoprotein N-acyltransferase
This is an abbreviated version!
For detailed information about apolipoprotein N-acyltransferase, go to the full flat file.
Word Map on EC 2.3.1.269
-
2.3.1.269
-
apolipoproteins
-
n-acylation
-
triacylated
-
membrane-embedded
-
prolipoprotein
-
diacylglyceryl
-
phosphatidylglycerol
-
acyl-enzyme
-
braun
- 2.3.1.269
-
apolipoproteins
-
n-acylation
-
triacylated
-
membrane-embedded
- prolipoprotein
-
diacylglyceryl
- phosphatidylglycerol
- acyl-enzyme
-
braun
Reaction
Synonyms
ALP N-acyltransferase, apolipoprotein N-acyl transferase, BCG_2070c, lnt, LntMs, NMB0713, Ppm1Tb
ECTree
Advanced search results
General Information
General Information on EC 2.3.1.269 - apolipoprotein N-acyltransferase
Please wait a moment until all data is loaded. This message will disappear when all data is loaded.
evolution
malfunction
metabolism
physiological function
additional information
apolipoprotein N-acyltransferase (Lnt) belongs to the nitrilase superfamily. Nitrilases are multimeric proteins that contain a common Glu-Lys-Cys catalytic triad that hydrolyse carbon-nitrogen bonds
evolution
apolipoprotein N-acyltransferase Lnt is Lnt is a reverse amidase and belongs to the nitrilase superfamily. Nitrilases generally require the Glu/Lys/Cys catalytic triad's conformation, also found in Lnt, and have a conserved alphabetabetaalpha sandwich fold. First, the intermediate is formed by the nucleophilic attack on the sn-1-glycerophospholipid's carbonyl (in phosphatidylethanolamine (PE), preferentially). Second, the intermediate (acyl-Lnt) undergoes a nucleophilic attack by the alpha-amino group of the protein substrate generating the triacylated lipoprotein
evolution
the enzyme is a member of the nitrilase superfamily which catalyses hydrolysis or condensation of carbon-nitrogen amine and nitrile bonds
-
depletion of apolipoprotein N-acyltransferase causes mislocalization of outer membrane lipoproteins in Escherichia coli
malfunction
Acinetobacter species can tolerate a complete loss-of-function mutation in gene lnt. Absence of a fully functional Lnt impairs modification of lipoproteins, increases outer membrane permeability and susceptibility to antibiotics, and alters normal cellular morphology. In addition, loss of lnt triggers a global transcriptional response to this added cellular stress. Without Lnt, the bacterial cell envelope becomes more permeable and modification of outer membrane lipoproteins is impaired. Cells of the lnt mutant have structural defects. The genome expression profile of Acinetobacter baylyi changes in response to lnt mutation. Phenotypes, overview
malfunction
Acinetobacter species can tolerate a complete loss-of-function mutation in gene lnt. Absence of a fully functional Lnt impairs modification of lipoproteins, increases outer membrane permeability and susceptibility to antibiotics, and alters normal cellular morphology. In addition, loss of lnt triggers a global transcriptional response to this added cellular stress. Without Lnt, the bacterial cell envelope becomes more permeable and modification of outer membrane lipoproteins is impaired. Phenotypes, overview
malfunction
-
Acinetobacter species can tolerate a complete loss-of-function mutation in gene lnt. Absence of a fully functional Lnt impairs modification of lipoproteins, increases outer membrane permeability and susceptibility to antibiotics, and alters normal cellular morphology. In addition, loss of lnt triggers a global transcriptional response to this added cellular stress. Without Lnt, the bacterial cell envelope becomes more permeable and modification of outer membrane lipoproteins is impaired. Cells of the lnt mutant have structural defects. The genome expression profile of Acinetobacter baylyi changes in response to lnt mutation. Phenotypes, overview
-
malfunction
-
Acinetobacter species can tolerate a complete loss-of-function mutation in gene lnt. Absence of a fully functional Lnt impairs modification of lipoproteins, increases outer membrane permeability and susceptibility to antibiotics, and alters normal cellular morphology. In addition, loss of lnt triggers a global transcriptional response to this added cellular stress. Without Lnt, the bacterial cell envelope becomes more permeable and modification of outer membrane lipoproteins is impaired. Cells of the lnt mutant have structural defects. The genome expression profile of Acinetobacter baylyi changes in response to lnt mutation. Phenotypes, overview
-
malfunction
Acinetobacter baumannii AB5075-UW
-
Acinetobacter species can tolerate a complete loss-of-function mutation in gene lnt. Absence of a fully functional Lnt impairs modification of lipoproteins, increases outer membrane permeability and susceptibility to antibiotics, and alters normal cellular morphology. In addition, loss of lnt triggers a global transcriptional response to this added cellular stress. Without Lnt, the bacterial cell envelope becomes more permeable and modification of outer membrane lipoproteins is impaired. Phenotypes, overview
-
genome expression profile of Acinetobacter baylyi changes in response to gene lnt mutation, overview
metabolism
in Gram-negative bacteria, lipid modification of proteins is catalysed in a three-step pathway. Apolipoprotein N-acyl transferase (Lnt) catalyses the third step in this pathway, whereby it transfers an acyl chain from a phospholipid to the amine group of the N-terminal cysteine residue of the apolipoprotein
metabolism
three membrane proteins are involved in processing precursors of lipoproteins, in the following order: the diacylglyceryl transferase Lgt, the signal peptidase LspA, and the N-acyltransferase Lnt
metabolism
-
genome expression profile of Acinetobacter baylyi changes in response to gene lnt mutation, overview
-
metabolism
-
genome expression profile of Acinetobacter baylyi changes in response to gene lnt mutation, overview
-
-
the enzyme is essential for the growth and viability of Salmonella typhimurium
physiological function
-
the enzyme required for in vitro and in vivo growth
physiological function
lipoproteins are important components of the cell envelope and are responsible for many essential cellular functions. They are produced by the post-translational covalent attachment of lipids that occurs via a sequential 3-step process controlled by three integral membrane enzymes. The last step of this process, unique to Gram-negative bacteria, is the N-acylation of the terminal cysteine by apolipoprotein N-acyltransferase (Lnt) to form the final mature lipoprotein
physiological function
Lnt acts on apolipoproteins. It catalyzes the transfer of an acyl chain from the sn-1 position of a lipid to the N-terminal cysteine, generating a triacylated lipoprotein. In its structure, a catalytic triad (E267/K335/C387) is accessible near TMHs 3, 4 and 5, and a long and unique loop (also described as an arm, lid, etc.) containing a short helix
physiological function
proper acylation of outer membrane lipoprotein BamD requires enzyme Lnt in Acinetobacter baylyi. Lnt is required for full maturation of outer membrane lipoprotein BamD
physiological function
-
proper acylation of outer membrane lipoprotein BamD requires enzyme Lnt in Acinetobacter baylyi. Lnt is required for full maturation of outer membrane lipoprotein BamD
-
physiological function
-
proper acylation of outer membrane lipoprotein BamD requires enzyme Lnt in Acinetobacter baylyi. Lnt is required for full maturation of outer membrane lipoprotein BamD
-
catalytic mechanism two-step reaction catalysed by Lnt, catalytic residue Cys387, the transacylation reaction uses a ping-pong mechanism, structure of the active site with catalytic triad and Glu343, overview. Lnt activity depends on its affinity to the lipid substrate. The enzyme contains an exo-membrane nitrilase domain fused to a transmembrane (TM) domain. The TM domain of Lnt contains eight TM helices which form a membrane-embedded cavity with a lateral opening and a periplasmic exit. The nitrilase domain is located on the periplasmic side of the membrane, with its catalytic cavity connected to the periplasmic exit of the TM domain. An amphipathic lid loop from the nitrilase domain interacts with the periplasmic lipid leaflet, forming an interfacial entrance from the lipid bilayer to the catalytic centre for both the lipid donor and acceptor substrates. Essential Lnt residues are located within the central cavity. Molecular dynamics simulations
additional information
-
catalytic mechanism two-step reaction catalysed by Lnt, catalytic residue Cys387, the transacylation reaction uses a ping-pong mechanism, structure of the active site with catalytic triad and Glu343, overview. Lnt activity depends on its affinity to the lipid substrate. The enzyme contains an exo-membrane nitrilase domain fused to a transmembrane (TM) domain. The TM domain of Lnt contains eight TM helices which form a membrane-embedded cavity with a lateral opening and a periplasmic exit. The nitrilase domain is located on the periplasmic side of the membrane, with its catalytic cavity connected to the periplasmic exit of the TM domain. An amphipathic lid loop from the nitrilase domain interacts with the periplasmic lipid leaflet, forming an interfacial entrance from the lipid bilayer to the catalytic centre for both the lipid donor and acceptor substrates. Essential Lnt residues are located within the central cavity. Molecular dynamics simulations
additional information
structure-function analysis of enzyme Lnt, significance of unique features in terms of substrate's recognition and binding mechanism influenced by exclusive residues, two transmembrane helices, and a flexible loop, structure comparisons, detailed overview. In the Lnt structure, a catalytic triad (E267/K335/C387) is accessible near TMHs 3, 4 and 5, and a long and unique loop (also described as an arm, lid, etc.) containing a short helix. The Lnt full reaction occurs as a two-step ping-pong. E343 as an important and conserved residue
additional information
two crystal forms of Lnt from Escherichia coli are observed. In one form a highly dynamic arm occurs that is able to restrict access to the active site as well as a covalent modification to the active site cysteine consistent with the thioester acyl-intermediate. In the second form, the enzyme crystallizes in an open conformation exposing the active site to the environment. Three unique Lnt molecules that when taken together suggest the movement of essential loops and residues are triggered by substrate binding that could control the interaction between Lnt and the incoming substrate apolipoprotein, mechanism, detailed overview. In the case of Lnt, the nitrilase domain catalyzes the attachment of a fatty acid derived from a phospholipid to the alpha-amino group of the N-terminal cysteine of the apolipoprotein creating the final mature lipoprotein. This attachment occurs via a proposed 2-step ping-pong mechanism where the first step is the acyl transfer of the phospholipid substrate to create a thioester linkage on the active site cysteine. The second step is the transfer of the acyl chain from this cysteine to the N-terminal cysteine of the apolipoprotein. This occurs at the catalytic triad of E267-K335-C387 where E267 acts as a general base to activate the nucleophile of the thiol group of C387 that can then attack the ester linkage between the acyl chain and the glycerol backbone of the phospholipid substrate to form the thioester acyl intermediate. K335 provides part of the oxyanion hole to stabilize this tetrahedral intermediate of the reaction. In the second step, with Lnt now in its thioester-acyl intermediate state, the alpha-amino group at the N-terminus of the incoming apolipoprotein attacks the thioester linkage to transfer the acyl chain to produce the final mature lipoprotein. Similar to the first step, K335 stabilizes the tetrahedral intermediate of the reaction. Docking study and molecular dynamics simulations
additional information
-
two crystal forms of Lnt from Escherichia coli are observed. In one form a highly dynamic arm occurs that is able to restrict access to the active site as well as a covalent modification to the active site cysteine consistent with the thioester acyl-intermediate. In the second form, the enzyme crystallizes in an open conformation exposing the active site to the environment. Three unique Lnt molecules that when taken together suggest the movement of essential loops and residues are triggered by substrate binding that could control the interaction between Lnt and the incoming substrate apolipoprotein, mechanism, detailed overview. In the case of Lnt, the nitrilase domain catalyzes the attachment of a fatty acid derived from a phospholipid to the alpha-amino group of the N-terminal cysteine of the apolipoprotein creating the final mature lipoprotein. This attachment occurs via a proposed 2-step ping-pong mechanism where the first step is the acyl transfer of the phospholipid substrate to create a thioester linkage on the active site cysteine. The second step is the transfer of the acyl chain from this cysteine to the N-terminal cysteine of the apolipoprotein. This occurs at the catalytic triad of E267-K335-C387 where E267 acts as a general base to activate the nucleophile of the thiol group of C387 that can then attack the ester linkage between the acyl chain and the glycerol backbone of the phospholipid substrate to form the thioester acyl intermediate. K335 provides part of the oxyanion hole to stabilize this tetrahedral intermediate of the reaction. In the second step, with Lnt now in its thioester-acyl intermediate state, the alpha-amino group at the N-terminus of the incoming apolipoprotein attacks the thioester linkage to transfer the acyl chain to produce the final mature lipoprotein. Similar to the first step, K335 stabilizes the tetrahedral intermediate of the reaction. Docking study and molecular dynamics simulations