gene reactions comment
B0084 MCTP1App,MCTP2App (FtsI (penicillin-binding protein 3, PBP3) is an essential cell division protein |CITS: [1103132]| which is present at low abundance of about 100 molecules per cell |CITS: [9379897]|. Binding of beta-lactam antibiotics to FtsI inhibits FtsI activity and is lethal |CITS: [3902760]|. FtsI is localized to the division site; localization is dependent on FtsZ, FtsA, FtsQ, FtsL, and FtsW, but not FtsN |CITS: [9379897][9603865][9882665][11703663][11807049]|. FtsA alone can force FtsI to localize to the cell poles independently of the Z ring, suggesting that FtsA and FtsI interact in a separate pathway |CITS: [15516588]|. This is supported by bacterial two-hybrid evidence |CITS: [14663069]|. FtsI contains a small N-terminal cytoplasmic domain, a transmembrane helix and a C-terminal periplasmic region that can be separated into a noncatalytic and a catalytic domain |CITS: [2677607][9614966]|. The cytoplasmic domain and transmembrane helix are essential for its role in cell division |CITS: [9260951][8631709]|. The transmembrane helix is necessary and sufficient for localization of FtsI to the Z ring |CITS: [9882665][14702319][15601716]|. The noncatalytic periplasmic domain is required for recruitment of FtsN |CITS: [14702319]|. The catalytic C-terminal domain contains the transpeptidase activity and is involved in peptidoglycan synthesis at the division septum |CITS: [6450748][3531167][9260951]|. Constriction of the Z ring during cell division requires the transpeptidase activity of FtsI |CITS: [9012823]|. The C-terminal 349 amino acids contain the penicillin-binding region |CITS: [6092133]|. A fraction of FtsI molecules are modified with glycerol and fatty acids |CITS: [3053665]|. Overproduction of FtsI suppresses the filamentous phenotype of strains with mutations in ftsI and ftsH |CITS: [3316193]|. Inactivation of FtsI by binding of beta-lactam antibiotics or mutagenesis induces the SOS response via the DpiBA two-component signal transduction system. The resulting cell division arrest may enable survival of the cells despite exposure to otherwise lethal antibiotics |CITS: [15308764]|. Selected reviews: |CITS: [15491352][12626683][9614966]|)
B0433 AGM4Pt2pp,AGMt2pp,AGM3Pt2pp (AmpG is a member of the major facilitator superfamily of transporters, and together with AmpD, is essential for induction of the AmpC Β-lactamase and is involved in the recycling of cell wall peptides |CITS: [90120556] [94049112] [95291453] [96100441]|. Mutants in ampG are unable to induce ampC and display greatly increased cell wall turnover |CITS: [95009971]|. AmpG is responsible for the transport of precursors of the anhMurNAc tripeptide into the cytoplasm |CITS:[8878601]|. These precursors are the products of peptidoglycan degradation and include the disaccharide GlcNAc-anhMurNAc as well as GlcNAc-anhMurNAc-oligopeptides (tri-, tetra-, and pentapeptides). Transport is dependent on the proton motive force |CITS:[12426329]|. Following uptake of these muropeptides, they are degraded, releasing the components which can subsequently be used in cell wall synthesis |CITS: [95302966]|. Experiments with β-lactamase fusions show AmpG contains two large cytoplasmic loops and 10 transmembrane segments |CITS:[15728916]|. Cytosolic muramyl peptides probably induce expression of ampC by binding to its regulator AmpR |CITS: [97302495]|.)
B0635 MCTP1App,MCTP2App (The mrdA (or pbpA) gene encodes the PBP2 protein responsible for maintaining the rod cell shape and mecillinam sensitivity in E. coli along with rodA |CITS:[6243629]|, |CITS:[1091862]|. The pbpA and rodA genes are members of a single transcriptional unit called the rodA operon, and rodA also has its own promoter within the pbpA gene |CITS:[2644207]|, |CITS:[6300030]|. Biochemical assays have shown that PBP2 is probably a bifunctional enzyme involved in the formation and cross-linking of peptidoglycan by transglycosylation and transpeptidation |CITS:[3009484]|. The active site was identified by the SXXK box at serine 330 |CITS:[3533535]|. The transpeptidase activity and penicillin-binding property of PBP2 are separable |CITS:[2656638]|. PBP2 exists at an estimated 10 to 20 copies per cell |CITS:[319999]|. The pbpA gene has been found to be deleterious for growth at high copy number |CITS:[6348028]|. PBP2 has no signal peptide, and a stretch of 25 non-ionic amino acids in the N-terminal region anchors the protein in the inner membrane |CITS:[3533535]|. GFP-PBP2 fusions have been shown to localize in the cylindrical portion of the cell membrane as well as at the site of constriction prior to division, but not in the old pole. The signal at the site of constriction disappears just before separation of daughter cells. This localization at mid-cell was dependent upon active PBP3, though PBP2 was found to not be a stable component of the divisome. PBP2 is active at the division site and required to maintain the diameter of the newly formed pole there |CITS:[12519203]|. Mutation or inhibition of PBP2 alone or coupled with mutation or inhibition of other proteins involved in murein synthesis or cell division have been isolated and characterized. |CITS:[345275]|, |CITS:[201607]|, |CITS:[363690]|, |CITS:[6243629]|, |CITS:[6451612]|, |CITS:[7007327]|, |CITS:[7027927]|, |CITS:[3894330]|, |CITS:[2066344]|, |CITS:[8407846]|, |CITS:[2656638]|, |CITS:[1038366]|, |CITS:[1103132]|, |CITS:[11418550]|. Buoyant density studies of pbpA mutants have been performed |CITS:[1885519]|. )
B0732 MANPGH (The mngB gene encodes an alpha-mannosidase |CITS: [14645248]|.)
B0839 MDDCP1pp,MDDCP3pp,MDDCP5pp,MDDCP2pp,MDDCP4pp (DacC is a penicillin-binding protein that is required for proper cell morphology and provides some resistance to penicillin |CITS: [1447130][12354237][6215397]|. It is one of four DD-carboxypeptidase low-molecular weight PBPs in Escherichia coli (along with PBP4, PBP6 and DacD) that modify peptidoglycans through the removal of the terminal D-alanine from pentapeptide side chains |CITS:[368033]|, |CITS:[8955390]|. The carboxy-terminus of DacC is capable of forming an alpha helix and interacts with membranes chiefly through hydrophobic forces |CITS: [9371419][9858668]|. Deletion of this membrane-anchoring portion of the protein produces soluble DacC. Whereas overexpression of native DacC results in membrane vesicles in the cystoplasm, overexpression of this soluble variant yields inclusion bodies. Both forms of DacC can be purified with Procion rubine MX-B and subsequently bind stoichiometrically with penicillin |CITS: [1447130]|. Despite being part of a family of D-alanine carboxypeptidases, DacC lacks detectable activity against bisacetyl-L-lysine-D-alanyl-D-alanine and other test substrates |CITS: [1447130]|. Deletions in dacC are viable, though slightly penicillin sensitive |CITS: [6215397]|. dacC dacA double mutants are viable, though they show defects in morphology and cell division when bolA, which is required for dacC expression on entry to stationary phase, is overexpressed |CITS: [3903044][12354237][2684651]|. A complete deletion of dacA-D is also viable, as is a strain lacking eight of the known penicillin-binding protein genes, dacC among them |CITS: [8955390][10383966]|. Overexpression of DacC allows cell division in ftsI23 mutants, but leads to cell lysis during early exponential growth |CITS: [2254246][11325933]|.)
B1193 MLTGY4pp,MLTGY1pp,MLTGY2pp,MLTGY3pp (EmtA is a lytic endotransglycosylase which is expressed in Escherichia coli as a membrane-bound lipoprotein. Overexpression of emtA results in the hydrolysis of glycan strands isolated from the murein (peptidoglycan) sacculus, which serves as a bacterial exoskeleton |CITS:[9642199]|. It is believed that the emtA gene product, like other murein hydrolases, is involved in cleavage of the net-like murein structure thereby allowing for cell enlargement and division and also for localized opening of the peptidoglycan layer to allow the export of bulky compounds such as DNA, toxins, flagella, and fimbrial proteins |CITS:[8824596]|, |CITS:[9642199]|.)
B1325 ALAGLUE (YcjG is an L-Ala-D/L-Glu epimerase (of the enolase superfamily) that may act on murein |CITS: [11747447]|. The substrate specificity of the enzyme is not strict |CITS: [11747447]|. Kinetic characterization is performed; the k(cat)/K(M) with L-Ala-D/L-Glu as a substrate is about 10(4) per M per sec|CITS: [11747447]|. The crystal structure has been determined |CITS: [11747448]|.)
B2027 O16AP3pp,O16AP2pp,O16AP1pp (In E. coli strains O8 and O9, the orthologous Wzz protein was shown to control the length of the O-antigen component of lipopolysaccharide |CITS: [8606163][9383197]|. Regulation of O-antigen chain length is required for virulence of Salmonella typhimurium |CITS: [12603743]|. E. coli K12 does not produce O-antigen. WzzB appears to be present as a dimer in the membrane |CITS: [16079137]|. rol: "regulator of O length" |CITS: [1715860]| cld: "chain length determinant" |CITS: [7682279]|)
B2032 O16GLCT1 (No information about this protein was found by a literature search conducted on November 29, 2005.)
B2033 O16AT (No information about this protein was found by a literature search conducted on February 26, 2004.)
B2034 O16GALFT (WbbI (GalF) is not required for colanic acid biosynthesis |CITS: [8759852]|. In E. coli O7:K1, GalF binds to and regulates GalU UDP-glucose pyrophosphorylase |CITS: [8971705]|. In E. coli K30, GalF is involved in biosynthesis of capsular polysaccharide, and transcription of the galF gene is activated by RcsB |CITS: [12581358]|.)
B2035 O16AP1pp,O16AP2pp,O16AP3pp (Lipopolysaccharide (LPS) is a major component of the outer membrane in most gram-negative bacteria. It consists of lipid A, core oligosaccharide, and O polysaccharide or O-specific antigen. E. coli K-12 does not normally express O-specific LPS due to mutations in its laterally acquired rfb gene cluster. rfc is found within the rfb gene cluster and encodes an O-antigen polymerase |CITS:[7517390],[7517391]|. When the rfb-50 mutation of W3110 is complemented with the rfb cluster from strain WG1, O16 O antigen is synthesized |CITS:[7517391]|.)
B2701 MLTGY1pp,MLTGY2pp,MLTGY3pp,MLTGY4pp (MltB is one of three (along with MltA and Slt70) major lytic endotransglycosylases expressed in Escherichia coli. MltA and MltB are expressed as membrane-bound lipoproteins. Expression of MltB in cells grown in the presence of H-3 palmitate followed by SDS-PAGE analysis resulted in fluorographic visualization of a labeled band corresponding to the 36 kDa mass of MltB, demonstrating the lipoprotein character of MltB. Additionally, in the presence of globomycin, an inhibitor of the lipoprotein signal peptidase, a larger protein, the prolipoprotein form of MltB, was found to accumulate. Overexpression of mltB resulted in a 55-fold increase in murein hydrolase activity in the membrane fraction and subsequent cell lysis. Membrane fractionation followed by sucrose-density-gradient centrifugation indicated that most of the induced hydrolytic activity was located in the outer and intermediate membrane fractions. A deletion of the mltB gene showed no obvious phenotype |CITS:[746170]|, while a triple mltA, mltB, and slt70 mutant resulted in a 72% reduction in murein turnover |CITS:[10572120]|.)
B2813 MLTGY1pp,MLTGY3pp,MLTGY4pp,MLTGY2pp (MltA is one of three (along with MltB and Slt70) major lytic endotransglycosylases expressed in Escherichia coli. MltA and MltB are expressed as membrane-bound lipoproteins. Overexpression of MltA resulted in elevated levels of a membrane fraction protein with a molecular mass corresponding to the mass of the purified MltA protein |CITS:[8288527]|. Expression of MltA in cells grown in the presence of H-3 palmitate followed by SDS-PAGE analysis resulted in fluorographic visualization of a labeled band corresponding to the 39 kDa mass of MltA, demonstrating the lipoprotein character of MltA |CITS:[6988430]|. Sucrose gradient centrifugation studies have shown that MltA is localized to the outer membrane |CITS:[9287002]|. Induced overexpression of MltA resulted in lysis of cells grown at 30 degrees Celsius, the optimal temperature for enzymatic activity, but not at 37 degrees. Furthermore the expressed activity was able to hydrolyze both murein sacculi as well as isolated glycan strands |CITS:[9287002]|. A triple mltA, mltB, and slt70 mutant resulted in a 72% reduction in murein turnover |CITS:[10572120]|.)
B2835 2AGPG180tipp,2AGPA140tipp,2AGPA180tipp,2AGPG120tipp,2AGPG181tipp,2AGPA181tipp,2AGPA141tipp,2AGPA161tipp,2AGPA120tipp,2AGPA160tipp,2AGPG140tipp,2AGPG141tipp (LplT is a major facilitator superfamily (MFS) protein that acts as a flippase for transbilayer movement of lysophospholipids. Mutation experiments and transporter assays have determined LplT is responsible for the facilitated diffusion of lysophospholipids to the cytoplasmic portion of the inner membrane providing substrate for the bifunctional enzyme 2-acyl-GPE acyltransferase/acyl-ACP synthetase (Aas). lplT forms an operon with the aas gene |CITS:[15661733]|.)
B2963 MLTGY3pp,MLTGY2pp,MLTGY4pp,MLTGY1pp (E. coli contains a large number of murein hydrolase enzymes. MltC belongs to the family of lytic transglycosylases which degrade GlcNAcMurNAc glycan strands, resulting in the formation of a 1,6-anhydro-MurNAc residue at the released product. These enzymes are involved in the cleavage of the septum during cell division. Peptidoglycan hydrolase activity of MltC was demonstrated |CITS: [9158737]|. A mutant containing deletions in mltC, mltD, and mltE has a defect in cell separation, growing as short chains of cells |CITS: [12399477]|. These chain-forming mutants have a defect in the barrier function of the outer membrane. A mutant strain lacking all six known lytic transglycosylases (mltA mltB mltC mltD mltE slt) is unable to induce β-lactamase and is more susceptible to certain high-molecular weight antibiotics which are normally inactive against Gram-negative bacteria, such as bacitracin, gallidermin and vancomycin |CITS: [15793119]|. Expression of mltC is induced by oxidative stress via SoxS |CITS: [14594836]|. Review: |CITS: [7487333]|)
B3396 MCTP1Bpp,MCTP2App,MCTP1App (PBP1A is the product of the mrcA gene |CITS:[3882429]|. PBP1A is a bifunctional, inner membrane enzyme catalyzing the transglycosylation and transpeptidation of murein (peptidoglycan) precursors in the formation of the murein sacculus |CITS:[9529891]|. The amino terminus contains a signal sequence |CITS:[3882429]|. PBP1A is able to dimerize without disulfide bonds, but doesn't form a complex with PBP1B |CITS:[12057973]|. Either PBP1A or PBP1B (the other major bifunctional enzyme in murein synthesis with a different penicillin-binding affinity) is required for cell elongation because a PBP1A-PBP1B double mutation is lethal |CITS:[1103132][341159][345275][2993822]|. Experiments have been performed involving inhibition or mutation of PBP1A alone or coupled with inhibition or mutation of other proteins involved in cell division and murein metabolism |CITS:[7007327][2211517][2066344][10383966]|.)
B3622 O16A4Lpp,ECA4OALpp (The lipopolysaccharide of E. coli K-12 consists of two major components: the hydrophobic lipid A moiety inserted into the outer membrane and the phosphorylated core oligosaccharide |CITS:[12045108]|. E. coli K-12 does not produce O antigen to attach to the LPS core due to a defect in the rfb gene cluster which can be complemented with genes from a second, independent rfb mutant to produce an O16 type O antigen |CITS:[7517391]|. E. coli K-12 may have two major pathways for LPS biosynthesis. One generates LPS cores suitable for O antigen attachment, and a second generates lipooligosaccharides (LOS) with modifications to the core structure which prevent O antigen attachment |CITS:[1385388]|. WaaL is thought to be the O-antigen ligase in the lipopolysaccharide synthesis pathway. Unlike most LPS core biosynthesis genes, waaL has little sequence similarity to the counterpart gene in Salmonella enterica |CITS: [1624462]|. This diversity is thought to play a role in generating core specificity and species-specific attachment of O antigen |CITS: [1385388]|. WaaL may function together with WaaU |CITS: [9535865]|. Both WaaU and WaaL are required for the complementation of a waaK mutation in S. typhimurium LT2, suggesting an interaction between the two proteins |CITS:[1385388]|. WaaL is an inner membrane protein with 12 predicted membrane-spanning regions. Its C terminus is located in the cytoplasm |CITS: [15919996]|. Inactivation of waaL does not cause a detectable morphological phenotype; this is not surprising, because the K-12 strain lacks the O antigen |CITS: [1577693]|. However, waaL appears to be required for core completion |CITS: [1385388]|. A waaL mutant prevents core completion by rfp of Shigella dysenteriae 1, suggesting its own role in core completion |CITS:[1385388]|. Reviews: |CITS:[12045108],[9157235],[9791168],[7504166]|)
B3785 ECAP2pp,ECAP1pp,ECAP3pp (The Enterobacterial Common Antigen biosynthesis protein complex is responsible for synthesizing ECA polysaccharide chains from Lipid III precursors that have been transferred accross the inner membrane.)
B3793 ECAP2pp,ECAP3pp,ECAP1pp (The Enterobacterial Common Antigen biosynthesis protein complex is responsible for synthesizing ECA polysaccharide chains from Lipid III precursors that have been transferred accross the inner membrane.)
B4356 GALCTNLt2pp (The YjiZ protein is an uncharacterised member of the major facilitator superfamily (MFS) of transporters |CITS: [98190790]|. Based on sequence similarity, YjiZ may function as a proton-driven metabolite uptake system.)
B4358 GALCTLO (YjjN did not show dehydrogenase activity in a high-throughput screen of purified proteins |CITS: [15808744]|. )
B4392 MLTGY1pp,MLTGY2pp,MLTGY3pp,MLTGY4pp (Slt70 is involved in growth and recycling of peptidoglycan by catalyzing the lysis of the β-1,4 glycosidic bond between N-acetylmuramic acid and N-acetylglucosamine, producing 1,6-anhydromuropeptides at an optimal pH of 4.5 with a Km of 200 mg/L |CITS:[357]|. Slt70 forms a murein-metabolizing multi-enzyme complex with PBP3 and PBP7/8 |CITS:[8063800]|. PBP7/8 was shown to stabilize and stimulate the activity of Slt70 |CITS:[8063800]|. Slt70 activity is also modulated by the stringent response |CITS:[1970319]|. The structure of Slt70 has been determined by X-ray crystallography revealing a α-superhelix structure with the catalytic domain on top |CITS:[2184239],[8107871]|. The structure has also been determined to a resolution of 1.65 Å for its native form, 1.90 Å as a complex with 1,6-anhydromuropeptide |CITS:[10452894]|, and 2.8 Å as a complex with bulgecin A |CITS:[7548026]|, its inhibitor |CITS:[1400320]|. Overproduction of Slt70 resulted in growth inhibition and lysis of some cells, but a deletion mutant had no observable phenotype |CITS:[1938883]|. Review: |CITS:[9529891]| )