Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
SYSTEMATIC NAME
IUBMB Comments
UDP-alpha-D-glucose:alpha-L-glycero-D-manno-heptosyl-(1->3)-alpha-L-glycero-D-manno-heptosyl-(1->5)-[alpha-Kdo-(2->4)]-alpha-Kdo-(2->6)-lipid A glucosyltransferase
WaaG is membrane-bound, membrane association mechanism, overview. Binding of WaaG to membranes is analyzed by stopped-flow fluorescence and NMR diffusion experiments. Electrostatic interactions are required to bind WaaG to membranes while mere hydrophobic interactions are not sufficient. WaaG senses the membrane's surface charge density but there is no preferential binding to specific anionic lipids. The binding is weaker than expected for monotopic GTs but similar to peripheral GTs. Therefore, WaaG may be a peripheral GT and this can be of functional relevance in vivo since LPS synthesis occurs only when WaaG is membrane-bound. No C-terminal domain movement is observed under the experimental conditions
comparison of the sequence of MG1655, as the reference genome, and of parent strain ML115 reveals the presence of a 768-bp insertion sequence within lipopolysaccharide (LPS) glucosyltransferase I (WaaG). This mutation is implemented unintentionally during the development of ML115. LAR1 and LAR2 both have restored function of WaaG and a single amino acid change within the beta' subunit of RNA polymerase RpoC, and each has a unique mutation in the BasS-BasR two-component signal transduction system. The shared waaG and rpoC mutations are most likely due to the fact that these strains share a common ancestor
mutation of the enzyme results in lipopolysaccharide truncated immediately after the inner core heptose residues, which serve as the sites for phosphorylation. Mutation of waaG also destabilized the outer membrane. Structural analyses of waaG mutant lipopolysaccharide shows that the cause for this phenotype is a decrease in core phosphorylation
deletion of waaG has previously been reported to result in a truncated LPS core and loss of flagella. This is consistent with TEM imaging of our strains, in that flagella are visible for LAR1 but not for ML115. Restoration of WaaG increases membrane integrity and increases the membrane rigidity
mutant strains lacking ADP-heptose-LPS heptosyltransferase 2, lipopolysaccharide heptosyltransferase 1 or glucosyltransferase WaaG only synthesize lipopolysaccharide with different lengths. Flagella are observed on the cell surface of the wild-type strain but not the mutant strains. 965genes in the WaaG deleltion mutant are significantly regulated compared to the control strain. Although there are significant transcriptional differences among the ADP-heptose-LPS heptosyltransferase 2, lipopolysaccharide heptosyltransferase 1 or glucosyltransferase mutant strains, genes related to flagella assembly and bacterial chemotaxis are significantly down-regulated in all three strains
glycosyltransferase WaaG is involved in the synthesis of lipopolysaccharides (LPS) in Gram-negative bacteria and is previously categorized as a monotopic glycosyltransferase (GT). Membrane-associated GTs have the peculiar property that they catalyze the formation of a glycosidic bond between a hydrophilic donor substrate and a lipid acceptor molecule. Moreover, peripheral GTs can either be membrane-bound or soluble. WaaG binds membranes via electrostatic interactions. There is no specific binding to anionic lipids. WaaG senses the anionic surface charge density of the membrane. The N- and C-terminal domains both associate to the lipid membrane with similar changes in fluorescence properties of a reporter Trp residue positioned in either the N-terminal or C-terminal domain. WaaG is a peripheral membrane protein
retaining GTs show a front-face catalytic mechanism. Glycosyltransferases GTs constitute a diverse class of enzymes that catalyze the formation of glycosidic bonds. GTs are highly versatile as they catalyze the transfer of sugar moieties from activated donor molecules to a vast amount of acceptor molecules but are at the same time highly specific for donor and acceptor molecules
retaining GTs show a front-face catalytic mechanism. Glycosyltransferases GTs constitute a diverse class of enzymes that catalyze the formation of glycosidic bonds. GTs are highly versatile as they catalyze the transfer of sugar moieties from activated donor molecules to a vast amount of acceptor molecules but are at the same time highly specific for donor and acceptor molecules
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
CRYSTALLIZATION (Commentary)
ORGANISM
UNIPROT
LITERATURE
an exposed and largely alpha-helical 30-residue sequence, with a net positive charge and several aromatic amino acids, is the putative membrane-interacting region of WaaG. In the presence of dodecylphosphocholine, the membrane-interacting region adopts a three-dimensional structure remarkably similar to the segment in the crystal structure. The interaction of WaaG is conferred at least in part by the membrane-interacting region and electrostatic interactions play a key role in binding. During anchoring of WaaG to the inner membrane of Escherichia coli, the central part of membrane-interacting region inserts into one leaflet of the bilayer. In this model, electrostatic interactions as well as surface-exposed Tyr residues bind WaaG to the membrane
crystals of the enzyme and of its selenomethionine derivative are grown in 0.1 M MES (pH 6.75), 0.2 M NaBr, and 15% PEG 3350 at a protein concentration of 10 mg/ml. Microseeding is necessary to achieve reproducibility of the crystals. Crystals of the complex of the enzyme with UDP-2F-glucose are prepared by addition of 10 mM UDP-2F-glucose to the protein solution prior to crystallization. The structure of the enzyme is solved by single-wavelength anomalous dispersion with a selenomethionine version of the protein, at a resolution of 1.6 A, in the presence of UDP
reverse engineering of a strain of Escherichia coli previously evolved for increased tolerance of octanoic acid (C8), an attractive biorenewable chemical, resulting in increased C8 production, increased butanol tolerance, and altered membrane properties. Evolution is determined to have occurred first through the restoration of WaaG activity, involved in the production of lipopolysaccharides, then an amino acid change in RpoC, a subunit of RNA polymerase, and finally mutation of the BasS-BasR two component system. The WaaG and RpoC mutations both contribute to increased C8 titers, with the RpoC mutation appearing to be the major driver of this effect. Each of these mutations contributes to changes in the cell membrane. Increased membrane integrity and rigidity and decreased abundance of extracellular polymeric substances can be attributed to the restoration of WaaG. The restoration of waaG occurrs first, and relatively quickly, with only the ML115 version of waaG being observed at the end of the second transfer and only the restored version of waaG (waaGR) being observed at the end of the third transfer. The parent strain with restored WaaG (strain YC005) results in a growth rate and final OD. The evolved strain phenotype can be completely attributed to waaGR and rpoCH419P, the basR mutation is not required
activity assay for WaaG using 14C-labeled UDP-glucose and lipopolysaccharide purified from a WaaG deletion strain of Escherichia coli. Addition of the lipids phosphatidylglycerol and cardiolipin, as well as the detergent 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate increase activity
activity assay for WaaG using 14C-labeled UDP-glucose and lipopolysaccharide purified from a WaaG deletion strain of Escherichia coli. Addition of the lipids phosphatidylglycerol and cardiolipin, as well as the detergent 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate increase activity
Yethon, J.A.; Vinogradov, E.; Perry, M.B.; Whitfield, C.
Mutation of the lipopolysaccharide core glycosyltransferase encoded by waaG destabilizes the outer membrane of Escherichia coli by interfering with core phosphorylation