Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P43026 (lipopolysaccharide)
 62,215 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The isolation and characterization of two mutants of Escherichia coli K12 with an altered outer membrane protein c is described. The first mutant, strain CE1151, was isolated as a bacteriophage Me1 resistant strain which contains normal levels of protein c. Mutant cells adsorbed the phage with a strongly decreased rate. Complexes of purified nonheat modified wild type protein c and wild type lipopolysaccharide inactivated phage Me1, indicating that these components are required for receptor activity for phage Me1. When wild type protein c was replaced by protein c of strain CE1151, the receptor-complex was far less active, showing that protein c of strain CE1151 is altered. The second mutant produces a protein c with a decreased electrophoretic mobility, designated as protein c. An altered apparent molecular weight was also observed for one or more fragments obtained after fragmentation of the mutant protein with cyanogen bromide, trypsin and chymotrypsin. Alteration of protein c was not accompanied by a detectable alteration in protein b or its fragments. Both mutations are located at minute 48 of the Escherichia coli K12 linkage map. The results strongly suggest that meoA is the structural gene for protein c.
 ...
PMID:meoA is the structural gene for outer membrane protein c of Escherichia coli K12. 37 4

Freeze fracturing electron microscopy of Escherichia coli K12 cells showed that the outer fracture face of the outer membrane is densily occupied with particles. On the inner fracture face of the outer membrane, pits are visible, which are probably complementary to the particles at opposite fracture face. This observation suggests that the particles are micelle-like. In some mutants which lack one or more major outer membrane proteins the density of particles is reduced. The loss of protein d appeared to a prerequisite for this phenomenon. However, mutants which lack all glucose and heptose-bound phosphate in their lipopolysaccharide also have a reduction in particle density whereas, the amount of protein d is normal. Moreover, loss of lipopolysaccharide by EDTA treatment also caused a reduction in the density of particles. From these results it is hypothesized that the particles consist of lipopolysaccharide aggregates stabilized by divalent cations and probably complexed with protein and/or phospholipid.
 ...
PMID:Architecture of the outer membrane of Escherichia coli K12. II. Freeze fracture morphology of wild type and mutant strains. 40 48

The structure of the lipopolysaccharide from Escherichia coli K12, strain CR34 has been investigated. The lipopolysaccharide contains D-galactose, D-glucose, D-glucosamine, L-glycero D-mannoheptose, 2-keto-3-deoxyoctonate and lipid A. The core region does not contain D-glucosamine but contains galactose, glucose, and heptose in the molar ratios 1:3:6. Methylations were performed on the lipopolysaccharide and on the degraded polysaccharide obtained after acetic acid hydrolysis of the lipopolysaccharide. It was found that galactose is in terminal position partly in the form of galactopyranose, partly in the form of galactofuranose. A part of the heptose was found as unsubstituted heptofuranose. A mole of glucose was 1 leads to 2 linked and another mole of glucose was 1 leads to 6 linked. Periodate oxidation of the lipopolysaccharide followed by borohydride reduction eliminates galactose and only a part of glucose and of heptose. A mole of heptose gave mannose and thus it is unsubstituted in C6 and C7. One mole of glucose and one mole of heptose were not degraded by periodate oxidation.
 ...
PMID:[Study of the lipopolysaccharide from Escherichia coli K12 CR34]. 77 Jan 68

Freeze etching showed that the loss of each of the major outer membrane proteins b, c or d in mutants of Escherichia coki K12 does not influence the morphology of fracture faces of the outer membrane. Mutants that possess a heptose-deficient lipopolysaccharide and which in addition are deficient in one or more major outer membrane proteins exhibit a reduction in the number of intramembranous particles of the outer membrane. Moreover it was shown that lipid phase transitions induce a lateral lipid protein separation in the outer membrane, similar to that found in the cytoplasmic membrane.
 ...
PMID:Freeze etch morphology of outer membrane mutants of Escherichia coli K12. 77 30

Various Escherichia coli strains differ in the composition of their major outer membrane proteins. However, all E. coli K12 strains tested possess the same major outer membrane proteins a, b, c and d, although quantitative differences were detected. The influence of growth conditions on the composition of the major outer membrane proteins of E. coli was analyzed. It was found that neither the growth phase at which the cells are harvested, nor the fatty acid composition of the phospholipids has a considerable influence on the composition of these proteins. However, the composition of the growth medium, and, to a less extent, the growth temperature, have a pronounced influence. Certain mutants, changed in the composition of their lipopolysaccharide, are deficient in protein b. Also mutants deficient in protein c and d respectively, are described. Proteins b and c of E. coli K12 were found to be associated with peptidoglycan. Protein bands, corresponding with flagellin and pilin respectively, were identified.
 ...
PMID:Influence of cultural conditions and mutations on the composition of the outer membrane proteins of Escherichia coli. 78 62

Mutants of Escherichia coli K12, deficient in up to three major outer membrane proteins b, c and d have been constructed. Mutants that lack the lipopolysaccharide sugar heptose are deficient in protein b. All heptose-deficient strains are supersensitive to lysozyme, various antibiotics and detergents. They excrete the periplasmic enzyme ribonuclease I. Mutants deficient in proteins c and/or d have the same sensitivity towards these compounds as the parent strain. Cells of single, double and triple mutants are all rod-shaped. Electrophoretic analysis of cell envelope proteins indicates that in some mutants the protein deficiency is partially compensated for by increased amounts of one or two of the other major outer membrane proteins. Heptose-deficient strains have an increased amount of 2-keto-3-deoxyoctonate.
 ...
PMID:Heptose-deficient mutants of Escherichia coli K12 deficient in up to three major outer membrane proteins. 78 63

A method of isolation of the antiphage agent found in the preparations of bacterial DNA was developed. Chemical analysis of the preparations has shown that according to their qualitative and quantitative composition they are identical to the lipopolysaccharide of the bacterial membrane. On the basis of data on the antiphage activity of the D-LPS from E. coli B and E. coli K12 and on the basis of presumed analogy between the inactivation of the phage by the D-LPS preparations and the phage--cell interaction it is believed that different parts of the LPS serve as receptors for the phages T7 and T4: O-specific polysaccharide for T4 and core LPS for T7. On the basis of data on the activity of D-LPS of two species of the genus Aerobacter against the phage T7 it is presumed that Aerobacer and Escherichia are related according to the structure of their core LPS.
 ...
PMID:Identification and study of species specificity of antiphage lipopolysaccharides found in the preparations of bacterial DNA. 79 28

A method of isolation of the antiphage agent found in the preparations of bacterial DNA was developed. Chemical analysis of the preparations has shown that according to their qualitative and quantitative composition they are identical to the lipopolysaccharide of the bacterial membrane. On the basis of data on the antiphage activity of the D-LPS from E. coli B and E. coli K12 and on the basis of presumed analogy between the inactivation of the phage by the D-LPS preparations and the phage -- cell interaction it is believed that different parts of the LPS serve as receptors for the phages T7 and T4: O-specific polysaccharide for T4 and core LPS for T7. On the basis of data on the activity of D-LPS of two species of the genus Aerobacter against the phage T7 it is presumed that Aerobacer and Escherichia are related according to the structure of their core LPS.
 ...
PMID:Identification and study of species specificity of antiphage lipopolysaccharides found in the preparations of bacterial DNA. 79 82

Protein II*, one of the major Escherichia coli outer cell envelope membrane proteins has been characterized. The protein is heat-modifiable and perhaps due to complete unfolding and/or binding of sodium dodecylsulfate only at higher temperatures the modified protein exhibits a higher apparent molecular weight (33,000) than the non-modified form (28,000). Protein-chemical evidence as well as the behavior of two mutant proteins II* very strongly suggest that this protein consists of a single polypeptide chain and that in the strains studied there is no other major protein with similar characteristics. For another outer membrane protein, protein III (molecular weight 17,000), it has not yet been established if it should be classified as a major protein. Protein III consists of one or perhaps two polypeptide chains. The possibility existed that protein III is bound covalently to lipopolysaccharide, and this has been ruled out. Also, the lipopolysaccharide of the E. coli strains studied does not carry covalently bound protein in amounts anywhere near stoichiometry. N-on-protein substituents were neither found in protein II* nor in protein III. It is concluded that in E. coli B/r and the E. coli K12 strains used there are three major proteins: I, II, and IV; protein III may also belong to this class. There are not more major proteins than these. All four proteins are compared and discussed regarding their unknown functions and their relation to E. coli outer membrane proteins studied by other authors.
 ...
PMID:The major proteins of the Escherichia coli outer cell envelope membrane. Characterization of proteins II* and III, comparison of all proteins. 110 24

Mouse monoclonal antibodies (MAbs) specific for the lipopolysaccharide (LPS) core types R1, R2, and R3 of Escherichia coli and a cross-reactive MAb that binds to the LPS core of almost all E. coli were used in ELISA to determine the frequency of cores resembling R1, R2, and R3 in strains of E. coli isolated from clinical samples (blood and urine specimens) and from the feces of asymptomatic individuals. Of the 180 wild-type isolates, 123 were assigned to R1 core type, 14 to R2, and 18 to R3. Twenty-five wild-type E. coli isolates could not be assigned to a particular core type and may have either an R4 or K12 core or a previously unrecognized core type. R1 core type was associated with O types 1, 4, 6, 8, and 18 and with K1 or K5 capsules. R3 was associated with O15. O75 isolates could be of either R1 or R2 core type.
 ...
PMID:Frequencies of lipopolysaccharide core types among clinical isolates of Escherichia coli defined with monoclonal antibodies. 140 16


<< Previous 1 2 3 4 5 6 7 8 9 Next >>