The Enzyme Database

Displaying entries 51-54 of 54.

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EC 4.2.1.59     
Accepted name: 3-hydroxyacyl-[acyl-carrier-protein] dehydratase
Reaction: a (3R)-3-hydroxyacyl-[acyl-carrier protein] = a trans-2-enoyl-[acyl-carrier protein] + H2O
Other name(s): fabZ (gene name); fabA (gene name); D-3-hydroxyoctanoyl-[acyl carrier protein] dehydratase; D-3-hydroxyoctanoyl-acyl carrier protein dehydratase; β-hydroxyoctanoyl-acyl carrier protein dehydrase; β-hydroxyoctanoyl thioester dehydratase; β-hydroxyoctanoyl-ACP-dehydrase; (3R)-3-hydroxyoctanoyl-[acyl-carrier-protein] hydro-lyase; (3R)-3-hydroxyoctanoyl-[acyl-carrier-protein] hydro-lyase (oct-2-enoyl-[acyl-carrier protein]-forming); 3-hydroxyoctanoyl-[acyl-carrier-protein] dehydratase
Systematic name: (3R)-3-hydroxyacyl-[acyl-carrier protein] hydro-lyase (trans-2-enoyl-[acyl-carrier protein]-forming)
Comments: This enzyme is responsible for the dehydration step of the dissociated (type II) fatty-acid biosynthesis system that occurs in plants and bacteria. The enzyme uses fatty acyl thioesters of ACP in vivo. Different forms of the enzyme may have preferences for substrates with different chain length. For example, the activity of FabZ, the ubiquitous enzyme in bacteria, decreases with increasing chain length. Gram-negative bacteria that produce unsaturated fatty acids, such as Escherichia coli, have another form (FabA) that prefers intermediate chain length, and also catalyses EC 5.3.3.14, trans-2-decenoyl-[acyl-carrier protein] isomerase. Despite the differences both forms can catalyse all steps leading to the synthesis of palmitate (C16:0). FabZ, but not FabA, can also accept unsaturated substrates [4].
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 9030-85-7
References:
1.  Mizugaki, M., Swindell, A.C. and Wkil, S.J. Intermediate- and long-chain β-hydroxyacyl-ACP dehydrases from E. coli fatty acid synthetase. Biochem. Biophys. Res. Commun. 33 (1968) 520–527. [DOI] [PMID: 4881058]
2.  Sharma, A., Henderson, B.S., Schwab, J.M. and Smith, J.L. Crystallization and preliminary X-ray analysis of β-hydroxydecanoyl thiol ester dehydrase from Escherichia coli. J. Biol. Chem. 265 (1990) 5110–5112. [PMID: 2180957]
3.  Mohan, S., Kelly, T.M., Eveland, S.S., Raetz, C.R. and Anderson, M.S. An Escherichia coli gene (FabZ) encoding (3R)-hydroxymyristoyl acyl carrier protein dehydrase. Relation to fabA and suppression of mutations in lipid A biosynthesis. J. Biol. Chem. 269 (1994) 32896–32903. [PMID: 7806516]
4.  Heath, R.J. and Rock, C.O. Roles of the FabA and FabZ β-hydroxyacyl-acyl carrier protein dehydratases in Escherichia coli fatty acid biosynthesis. J. Biol. Chem. 271 (1996) 27795–27801. [DOI] [PMID: 8910376]
[EC 4.2.1.59 created 1972, modified 2012]
 
 
EC 4.6.1.14     
Accepted name: glycosylphosphatidylinositol diacylglycerol-lyase
Reaction: 6-(α-D-glucosaminyl)-1-phosphatidyl-1D-myo-inositol = 6-(α-D-glucosaminyl)-1D-myo-inositol 1,2-cyclic phosphate + 1,2-diacyl-sn-glycerol
For diagram of glycosylphosphatidyl-myo-inositol biosynthesis, click here
Other name(s): (glycosyl)phosphatidylinositol-specific phospholipase C; GPI-PLC; GPI-specific phospholipase C; VSG-lipase; glycosyl inositol phospholipid anchor-hydrolyzing enzyme; glycosylphosphatidylinositol-phospholipase C; glycosylphosphatidylinositol-specific phospholipase C; variant-surface-glycoprotein phospholipase C; 6-(α-D-glucosaminyl)-1-phosphatidyl-1D-myo-inositol diacylglycerol-lyase (1,2-cyclic-phosphate-forming)
Systematic name: 6-(α-D-glucosaminyl)-1-phosphatidyl-1D-myo-inositol 1,2-diacyl-sn-glycerol-lyase [6-(α-D-glucosaminyl)-1D-myo-inositol 1,2-cyclic phosphate-forming]
Comments: This enzyme is also active when O-4 of the glucosamine is substituted by carrying the oligosaccharide that can link a protein to the structure. It therefore cleaves proteins from the lipid part of the glycosylphostphatidylinositol (GPI) anchors. In some cases, the long-chain acyl group at the sn-1 position of glycerol is replaced by an alkyl or alk-1-enyl group. In other cases, the diacylglycerol is replaced by ceramide (see Lip-1.4 and Lip-1.5 for definition). The only characterized enzyme with this specificity is from Trypanosoma brucei, where the acyl groups are myristoyl, but the function of the trypanosome enzyme is unknown. Substitution on O-2 of the inositol blocks action of this enzyme. It is not identical with EC 3.1.4.50, glycosylphosphatidylinositol phospholipase D.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 129070-68-4
References:
1.  Hereld, D., Krakow, J.L., Bangs, J.D., Hart, G.W. and Englund, P.T. A phospholipase C from Trypanosoma brucei which selectively cleaves the glycolipid on the variant surface glycoprotein. J. Biol. Chem. 261 (1986) 13813–13819. [PMID: 3759991]
2.  Carnall, N., Webb, H. and Carrington, M. Mutagenesis study of the glycosylphosphatidylinositol phospholipase C of Trypanosoma brucei. Mol. Biochem. Parasitol. 90 (1997) 423–432. [DOI] [PMID: 9476790]
3.  Armah, D.A. and Mensa-Wilmot, K. Tetramerization of glycosylphosphatidylinositol-specific phospholipase C from Trypanosoma brucei. J. Biol. Chem. 275 (2000) 19334–19342. [DOI] [PMID: 10764777]
[EC 4.6.1.14 created 1989 as EC 3.1.4.47, transferred 2002 to EC 4.6.1.14]
 
 
EC 7.5.2.6     
Accepted name: ABC-type lipid A-core oligosaccharide transporter
Reaction: ATP + H2O + lipid A-core oligosaccharide[side 1] = ADP + phosphate + lipid A-core oligosaccharide[side 2]
Other name(s): MsbA; lipid flippase; ATP-dependent lipid A-core flippase
Systematic name: ATP phosphohydrolase (ABC-type, lipid A-core oligosaccharide-translocating)
Comments: An ATP-binding cassette (ABC) type transporter, characterized by the presence of two similar ATP-binding domains/proteins and two integral membrane domains/proteins. The enzyme, best characterized from the bacterium Escherichia coli, is located in the inner membrane and mediates the movement of lipid A attached to the core oligosaccharide from the cytoplasm to the periplasmic side of the inner membrane, an important step in the lipopolysaccharide biosynthetic pathway. Not to be confused with EC 7.5.2.5, ABC-type lipopolysaccharide transporter (LptB), which is implicated in the translocation of LPS from the inner membrane to the outer membrane and acts later in the process.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB
References:
1.  Karow, M. and Georgopoulos, C. The essential Escherichia coli msbA gene, a multicopy suppressor of null mutations in the htrB gene, is related to the universally conserved family of ATP-dependent translocators. Mol. Microbiol. 7 (1993) 69–79. [PMID: 8094880]
2.  Zhou, Z., White, K.A., Polissi, A., Georgopoulos, C. and Raetz, C.R. Function of Escherichia coli MsbA, an essential ABC family transporter, in lipid A and phospholipid biosynthesis. J. Biol. Chem. 273 (1998) 12466–12475. [PMID: 9575204]
3.  Singh, H., Velamakanni, S., Deery, M.J., Howard, J., Wei, S.L. and van Veen, H.W. ATP-dependent substrate transport by the ABC transporter MsbA is proton-coupled. Nat. Commun. 7:12387 (2016). [PMID: 27499013]
[EC 7.5.2.6 created 2018]
 
 
EC 7.5.2.14     
Accepted name: ABC-type homopolymeric O-antigen exporter
Reaction: ATP + a lipid-linked O antigen[cytosol] + H2O = ADP + phosphate + a lipid-linked O antigen[periplasm]
Other name(s): wzm (gene name); wzt (gene name)
Systematic name: ATP phosphohydrolase (ABC-type, homopolymeric O-antigen exporting)
Comments: Unlike heteropolymeric O antigens, which are polymerized in the periplasm by EC 2.4.99.27, O antigen polymerase Wzy, homopolymeric O antigens are polymerized inside the cytoplasm by a progressive transfer of sugar monomers to a growing chain attached to a polyprenyl diphosphate membrane anchor. When the chain reaches its full length it is transported across the cytoplasmic membrane by this ABC-type transporter, which consists of an ATP-binding subunit (Wzt) and an integral membrane protein (Wzm). Wzm proteins are poorly conserved in their primary sequence. Once in the periplasm, the O antigen is ligated to the lipid A-core complex by EC 2.4.99.26, O-antigen ligase.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Kido, N., Torgov, V.I., Sugiyama, T., Uchiya, K., Sugihara, H., Komatsu, T., Kato, N. and Jann, K. Expression of the O9 polysaccharide of Escherichia coli: sequencing of the E. coli O9 rfb gene cluster, characterization of mannosyl transferases, and evidence for an ATP-binding cassette transport system. J. Bacteriol. 177 (1995) 2178–2187. [DOI] [PMID: 7536735]
2.  Rocchetta, H.L. and Lam, J.S. Identification and functional characterization of an ABC transport system involved in polysaccharide export of A-band lipopolysaccharide in Pseudomonas aeruginosa. J. Bacteriol. 179 (1997) 4713–4724. [DOI] [PMID: 9244257]
3.  Cuthbertson, L., Powers, J. and Whitfield, C. The C-terminal domain of the nucleotide-binding domain protein Wzt determines substrate specificity in the ATP-binding cassette transporter for the lipopolysaccharide O-antigens in Escherichia coli serotypes O8 and O9a. J. Biol. Chem. 280 (2005) 30310–30319. [DOI] [PMID: 15980069]
4.  Cuthbertson, L., Kimber, M.S. and Whitfield, C. Substrate binding by a bacterial ABC transporter involved in polysaccharide export. Proc. Natl. Acad. Sci. USA 104 (2007) 19529–19534. [DOI] [PMID: 18032609]
5.  Mann, E., Mallette, E., Clarke, B.R., Kimber, M.S. and Whitfield, C. The Klebsiella pneumoniae O12 ATP-binding cassette (ABC) transporter recognizes the terminal residue of its O-antigen polysaccharide substrate. J. Biol. Chem. 291 (2016) 9748–9761. [DOI] [PMID: 26934919]
6.  Mann, E., Kelly, S.D., Al-Abdul-Wahid, M.S., Clarke, B.R., Ovchinnikova, O.G., Liu, B. and Whitfield, C. Substrate recognition by a carbohydrate-binding module in the prototypical ABC transporter for lipopolysaccharide O-antigen from Escherichia coli O9a. J. Biol. Chem. 294 (2019) 14978–14990. [DOI] [PMID: 31416837]
[EC 7.5.2.14 created 2023]
 
 


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