Proc Natl Acad Sci U S A
February 1984
Analysis of amino acid sequences reported for the major outer membrane proteins of Escherichia coli, including the porins (OmpF, OmpC, and PhoE), the phage lambda receptor (LamB), and another protein (OmpA), revealed several regions of local homology that is statistically significant. The implications of this observation are discussed in relation to the evolutionary origins of these proteins, as well as to the mechanism of export of these proteins to the outer membrane.
View Article and Find Full Text PDFThe present study showed that the presence or absence of a new component of major urinary proteins (Mups), which is found in MOA mice, an inbred strain of Mus musculus molossinus (Japanese wild mice), is controlled by a single codominant gene locus. The linkage analysis shows that the locus is on chromosome 4, where the Mup-1 locus is assigned; its alleles, Mup-1a, and Mup-1b determine two phenotypic forms of MUPs in laboratory mice (M. m.
View Article and Find Full Text PDFImmunogenetics
February 1985
Immunofixation after isoelectric focusing revealed two forms of mouse C6, C6A and C6M, both of which consist of two major protein bands and one or more acidic minor bands. They were distinguishable by their different isoelectric point (pI) ranges: C6M has more acidic pI ranges (pH less than 6.2) than C6A (pH less than 6.
View Article and Find Full Text PDFThe differences in electrophoretic patterns of major urinary proteins (MUP's) due to sex, strain, and subspecies of the mouse (Mus musculus) were examined by the combined methods of agarose gel electrophoresis and immunofixation. The MUP's from the male of common laboratory inbred mice (M. m.
View Article and Find Full Text PDFIn one malE mutant known to be deficient in the transport of maltose and maltodextrins across the outer membrane, the altered MalE protein was shown to be defective in its interaction with the phage lambda receptor, or LamB protein, of the outer membrane.
View Article and Find Full Text PDFMutant and wild-type LamB proteins (phage lambda receptor proteins) were purified by affinity chromatography with immobilized maltose-binding protein, and their transport functions were tested in reconstituted liposomes. Two mutant proteins exhibited a marked decrease in affinity for immobilized maltose-binding protein, as well as altered transport rates.
View Article and Find Full Text PDFRates of diffusion of uncharged and charged solute molecules through porin channels were determined by using liposomes reconstituted from egg phosphatidylcholine and purified Escherichia coli porins OmpF (protein 1a), OmpC (protein 1b), and PhoE (protein E). All three porin proteins appeared to produce channels of similar size, although the OmpF channel appeared to be 7 to 9% larger than the OmpC and PhoE channels in an equivalent radius. Hydrophobicity of the solute retarded the penetration through all three channels in a similar manner.
View Article and Find Full Text PDFJ Bacteriol
January 1983
Wild-type Escherichia coli K-12 produces two porins, OmpF (protein 1a) and OmpC (protein 1b). In mutants deficient in both of these "normal" porins, secondary mutants that produce a "new" porin, protein PhoE (protein E), are selected for. We determined the properties of the channels produced by each of these porins by measuring the rates of diffusion of various cephalosporins through the outer membrane in strains producing only one porin species.
View Article and Find Full Text PDFWe present the sequence of gene malK which encodes a component of the system for maltose transport in E.coli K12. We also determined the position of deletion (S50) which fuses malK to the following gene lamB; the malK-lamB protein hybrid contains all of the malK protein.
View Article and Find Full Text PDFJ Bacteriol
November 1982
Pseudomonas aeruginosa is usually resistant to a wide variety of antibacterial agents, and it has been inferred, on the basis of indirect evidence, that this was due to the low permeability of its outer membrane. We determined the permeability of P. aeruginosa outer membrane directly, by measuring the rates of hydrolysis of cephacetrile, cephaloridine, and various phosphate esters by hydrolytic enzymes located in the periplasm.
View Article and Find Full Text PDFA strong homology was found between the amino acid sequences, deduced from DNA nucleotide sequences, of cytoplasmic membrane-associated components of the high affinity histidine transport system of Salmonella typhimurium (coded by the hisP gene) and the maltose-maltodextrin transport system of Escherichia coli (coded by the malK gene). When the HisP protein sequence was aligned with that of the NH2-terminal two-thirds of the MalK protein, 32% of the positions were identical, and an additional 35% were occupied by functionally similar amino acid residues. These results suggest that some, and possibly many, "periplasmic-binding protein-dependent" transport systems have evolved from a common ancestral system.
View Article and Find Full Text PDFA polymorphism was found in the electrophoretic mobilities of male-specific rat urinary proteins. The proteins (MUP-1) are inherited as a single autosomal trait. The Mup-1 locus possesses two codominant alleles Mup-1a (fast-migrating type) and Mup-1b (slowing migrating type).
View Article and Find Full Text PDFJikken Dobutsu
January 1982
The low plasma alkaline phosphatase (ALP) activity of the IS strain of rats was genetically analyzed by using the cross matings with the BN strain. In the F1 hybrids, the ALP activities were intermediate but largely biased to the low activity. In the (F1 x BN) back-cross progeny, the distributions of plasma ALP activities were apparently bimodal in both sexes.
View Article and Find Full Text PDFAnn Microbiol (Paris)
January 1982
The phage lambda receptor, or LamB, proteins have been purified from several missense lamB mutants, and the properties of the channel produced by these proteins were investigated in a reconstituted liposome system. In at least one mutant, a significant reduction in the sugar selectivity of the channel was observed, and another mutant protein interacted poorly with the maltose-binding protein immobilized on Sepharose beads.
View Article and Find Full Text PDFWhen Triton X-100/EDTA extracts of the outer membrane of Escherichia coli K12 were passed through a column containing maltose-binding protein covalently linked to Sepharose 6MB beads, the phage lambda receptor protein or LamB protein was quantitatively and specifically adsorbed to the column and was eluted with a solution containing 1 M NaCl, but not with that containing 0.5 M maltose. The binding did not take place when columns containing inactivated Sepharose beads alone, or Sepharose bound to histidine-binding protein of Salmonella typhimurium, were used.
View Article and Find Full Text PDFAntimicrob Agents Chemother
October 1981
Carbenicillin-resistant mutants of Escherichia coli K-12 and B/r were found to produce greatly diminished levels of the porin coded by the ompF gene. Physiological and ecological implications of these findings are discussed.
View Article and Find Full Text PDFNutrients usually cross the outer membrane of Escherichia coli by diffusion through water-filled channels surrounded by a specific class of protein, porins. In this study, the rates of diffusion of hydrophilic nonelectrolytes, mostly sugars and sugar alcohols, through the porin channels were determined in two systems, (a) vesicles reconstituted from phospholipids and purified porin and (b) intact cells of mutant strains that produce many fewer porin molecules than wild-type strains. The diffusion rates were strongly affected by the size of the solute, even when the size was well within the "exclusion limit" of the channel.
View Article and Find Full Text PDFThe maltose transport system of Escherichia coli contains at least five components, three of which, i.e. the products of lamB, malE, and malF genes, have so far been identified as constituents of the outer membrane, periplasmic space, and cytoplasmic membrane, respectively.
View Article and Find Full Text PDFA cluster of esterase loci has been identified on a segment of a rat linkage group V; however, the linear order of all the loci has not been established. We estimated the recombination frequencies of two locus combinations among five esterase loci (Es-1, Es-2, Es-3, Es-4, and Es-Si) and the linear order of the loci by using three sets of backcross matings: (1) (K:W x IS) x IS, (2) (K:W x IS) x IS, and (3) (SHR x W) x W). The linear order was determined to be ES-1-ES-4-ES-2-ES-3-ES-Si, although the order of ES-2 and Es-4 remains tentative.
View Article and Find Full Text PDFVesicles permeable to sucrose, but not to high molecular weight dextrans, were produced when fragments of mitochondrial outer membrane obtained from rat liver or mung bean seedlings were fused with liposomes of soybean phospholipids. By using this reconstitution assay, the channel-forming protein in the mung bean mitochondria was identified as protein(s) with an apparent molecular weight of 30,000 through differential detergent extraction and centrifugation in a sucrose density gradient. The channel was nonspecific, and allowed the diffusion of saccharides of up to 2000 to 8000 daltons.
View Article and Find Full Text PDF