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R W Hogg

Publications and source records attributed to R W Hogg.

At least 19 recordsLinked to original sources
PubMed1992

Escherichia coli K12 arabinose-binding protein mutants with altered transport properties.

The arabinose-binding protein (ABP) of Escherichia coli binds L-arabinose in the periplasm and delivers it to a cytoplasmic membrane complex consisting of the AraG and AraH proteins, for uptake into the cell. To study the interaction between the soluble and membrane components of this periplasmic transport system, regions of the ABP surface containing the opening of the arabinose-binding cleft were subjected to site-directed mutagenesis. Thirty-eight ABP variants containing one to three amino acid substitutions were recovered. ABP variants were expressed with wild-type AraG and AraH from a plasmid, in a strain lacking the chromosomal araFGH operon, and the whole cell uptake parameters, Ven (maximum initial velocity of arabinose entry) and K(en) (concentration of arabinose yielding half-maximal entry) were determined. Twenty-four mutants had normal Ven values, 3 mutants had Ven and K(en) values twice wild type, and 11 mutants had Ven and K(en) values 20-50% of wild type. Binding proteins that had altered uptake properties were each expressed, processed, and localized to the periplasm at levels equivalent to wild type. The mutant binding proteins behaved the same as wild type during purification, and each had a Kd (dissociation constant for bound arabinose) comparable to that of wild-type ABP. Mutations that resulted in altered uptake identified nine amino acids surrounding the arabinose-binding cleft, all of which are charged in the wild-type protein, and all of whose side chains project outward from the cleft. The evidence suggests that this surface of the binding protein and these nine charged loci play a major role in ABP interactions with the membrane complex.

Amino Acid Sequence↗
PubMed1991

Nucleotide sequence and analysis of the mgl operon of Escherichia coli K12.

The nucleotide sequence of the Escherichia coli K12 beta-methylgalactoside transport operon, mgl, was determined. Primer extension analysis indicated that the synthesis of mRNA initiates at guanine residue 145 of the determined sequence. The operon contains three open reading frames (ORF). The operator proximal ORF, mglB, encodes the galactose binding protein, a periplasmic protein of 332 amino acids including the 23 residue amino-terminal signal peptide. Following a 62 nucleotide spacer, the second ORF, mglA, is capable of encoding a protein of 506 amino acids. The amino-terminal and carboxyl-terminal halves of this protein are homologous to each other and each half contains a putative nucleotide binding site. The third ORF, mglC, is capable of encoding a hydrophobic protein of 336 amino acids which is thought to generate the transmembrane pore. The overall organization of the mglBAC operon and its potential to encode three proteins is similar to that of the ara FGH high affinity transport operon, located approximately 1 min away on the E. coli K12 chromosome.

Amino Acid Sequence↗
PubMed1989

Genetic reconstitution of the high-affinity L-arabinose transport system.

Expression plasmids containing various portions of araFGH operon sequences were assayed for their ability to facilitate the high-affinity L-arabinose transport process in a strain lacking the chromosomal copy of this operon. Accumulation studies demonstrated that the specific induction of all three operon coding sequences was necessary to restore high-affinity L-arabinose transport. Kinetic analysis of this genetically reconstituted transport system indicated that it functions with essentially wild-type parameters. Therefore, L-arabinose-binding protein-mediated transport appears to require only two inducible membrane-associated components (araG and araH) in addition to the binding protein (araF).

Arabinose↗
PubMed1988

Fatty acids as biological markers for bacterial symbionts in sponges.

Analyses of fatty acids with carbon numbers between C12 and C22 are reported for five Great Barrier Reef sponges. These analyses indicate that phototrophic cyanobacterial symbionts (blue-green algae) present in three of the sponges are chemically distinct, whereas the other two sponges do not contain cyanobacterial symbionts. All the sponges contain other, nonphototrophic bacteria. The fatty acid analyses indicate that the non-phototrophic bacterial populations present in the different sponges are distinct in both their chemical compositions and their abundances. Nonphototrophic bacteria are estimated to account for between 60 and 350 micrograms/g (extractable fatty acids:tissue wet weight), whereas cyanobacteria account for between 10 and 910 micrograms/g. One sponge (Pseudaxinyssa sp.) contains a relatively large amount of the isoprenoid acid, 4, 8, 12-trimethyltridecanoic acid; this acid is presumed to be derived from phytol, a degradation product of chlorophyll. This sponge also contains relatively large amounts of the nonmethylene interrupted fatty acid, octadeca-5,9-dienoic acid. Analyses of interior and cyanobacteria-rich surface tissues of this sponge indicate that these two acids are probably not associated with the symbiotic cyanobacteria.

Animals↗
PubMed1987

High-affinity L-arabinose transport operon. Gene product expression and mRNAs.

Various portions of the "high-affinity" L-arabinose transport operon were cloned into the plasmid expression vector pKK223-3 and the operon-encoded protein products were identified. The results indicate that three proteins are encoded by this operon. The first is a 33,000 Mr protein that is the product of the promoter-proximal L-arabinose binding protein coding sequence, araF. A 52,000 Mr protein is encoded by sequence 3' to araF and has been assigned to the araG locus. The sequence 3' to araG encodes a 31,000 Mr protein that has been assigned to the araH locus. Both the araG and araH gene products are localized in the membrane fraction of the cell, implying a role in the membrane-associated complex of the high-affinity L-arabinose transport system. Nuclease S1 protection studies indicate that two operon message populations are present in the cell, a full-length operon transcript and a seven- to tenfold more abundant binding protein-specific message. The relative abundance of these two message populations correlates with the differential expression of the binding protein and the membrane-associated proteins of the transport system.

Arabinose↗
PubMed1987

High-affinity L-arabinose transport operon. Nucleotide sequence and analysis of gene products.

The nucleotide sequence of the "high-affinity" L-arabinose transport operon has been determined 3' from the regulatory region and found to contain three open reading frames designated araF, araG and araH. The first gene 3' to the regulatory region, araF, encodes the 23-residue signal peptide and the 306-residue mature form of the L-arabinose binding protein (33,200 Mr). The binding protein, which has been described elsewhere, is hydrophilic, soluble and found in the periplasm of Escherichia coli. This gene is followed by an intragenic space of 72 nucleotides, which contains a region of dyad symmetry 23 nucleotides long capable of forming an 11-member stem-loop. The second gene, designated araG, contains an open reading frame capable of encoding an equally hydrophilic protein containing 504 residues (55,000 Mr). Following a 14-nucleotide spacer, which does not appear to have any secondary structure, the third open reading frame, herein designated araH, is capable of encoding a hydrophobic protein containing 329 residues (34,000 Mr) that can only be envisioned as having an integral membrane location. 3' to araH there is a T-rich region containing a 24-nucleotide area of dyad symmetry centered 55 nucleotides from the termination codon. Analysis of the derived primary sequences of the araG and araH products indicates the nature and potential features of these components. The araG protein was found to possess internal homology between its amino and carboxyl-terminal halves, suggesting a common origin. The araG gene product has been shown to be homologous to the rbsA gene product, the hisP product, the ptsB product and the malK product, all of which presumably play similar roles in their respective transport systems. Putative ATP binding sites are observed within the regions of homology. The araH gene product has been shown to be homologous to the rbsC gene product, which is the first observed homology between two purported membrane proteins.

Amino Acids↗
PubMed1983

The nucleotide sequences defining the signal peptides of the galactose-binding protein and the arabinose-binding protein.

The nucleotide sequences of the NH2-terminal regions of the mglB (galactose-binding protein) and the araF (arabinose-binding protein) genes have been determined. A "signal peptide" containing 23 amino acid residues immediately precedes the known sequence of the processed galactose-binding protein. The primary sequence of the signal peptide of the arabinose-binding protein has been redefined according to the established nucleotide sequence. The nucleotide sequences for the two signal peptides are preceded by apparent ribosome-binding sequences.

Amino Acid Sequence↗
PubMed1982

Proton nuclear magnetic resonance spectroscopy and ligand binding dynamics of the Escherichia coli L-arabinose binding protein.

The L-arabinose binding protein (ABP) from Escherichia coli was studied by proton nuclear magnetic resonance spectroscopy (1H NMR). Distinct spectral changes occur when ABP binds its natural ligand, L-arabinose, which involve resonances in the aromatic ring current shifted methyl, bulk methyl, methylene, aromatic, and amide proton regions of the spectra. Several amide resonances can be "protected" from deuterium exchange if L-arabinose is bound to ABP prior to deuterium oxide dialysis. On the basis of the pH dependence of their chemical shifts, two low-field resonances have been tentatively assigned to C2 protons of two of the three histidines present in ABP. These histidyl residues have pK values of 8.0 and 8.6 which support their involvement in ionic interactions observed earlier in the crystallographic analysis. One histidyl residue shows a small chemical shift change upon the addition of arabinose. When ABP binds D-galactose, changes in the spectra occur which are different than those observed when L-arabinose is bound. Binding of L-arabinose and D-galactose to the binding protein (ABP) was considered by equilibrium binding and fluorescence emission spectroscopy. ABP binds L-arabinose and D-galactose with high affinities (Kd's at 6 degrees C of 1.3 x 10(-7) and 1.9 x 10(-7) M, respectively), and both enthalpy and entropy contribute to the ABP-ligand association. When excited at 285 nm, ABP has a fluorescence emission maximum of 340 nm which is quenched and blue shifted (to 337 nm) upon binding L-arabinose. ABP binding D-galactose produced a similar emission shift but no fluorescence quenching.

Bacterial Proteins↗
PubMed1981

The amino acid sequence of the D-galactose-binding protein from Escherichia coli B/r.

The complete primary structure of the Escherichia coli B/r galactose-binding protein was determined by the automated sequencing of fragments produced by cleavage with cyanogen bromide, o-iodosobenzoic acid, limited trypsin digestion, mild acid hydrolysis, and Staphylococcus aureus strain V8 protease. The protein, which has 309 amino acids, is notable in the extent to which it differs from the L-arabinose-binding protein. Comparison of these two proteins indicates only about 18% homology despite the close structural resemblence of the molecules which they bind. The galactose-binding protein is the chemoreceptor initiating chemotaxis toward galactose, and it thus becomes the first protein component required for chemotaxis for which the primary structure is known. GM 24602

Amino Acid Sequence↗
PubMed1981

The amino acid sequence of the histidine binding protein of Salmonella typhimurium.

The amino acid sequence of the histidine binding protein of Salmonella typhimurium was determined by automated sequence analysis of reduced and S-pyridylethylated histidine binding protein and fragments derived by chemical and enzymatic cleavage of the native protein. The fragments were the products of cleavage at methionine residues by cyanogen bromide, cleavage at tryptophan residues by 2-nitrophenylsulfenyl-3-methyl-3-bromo-3H-indole (BrNps-skatole), limited enzymatic digestion at arginine residues, and enzymatic digestion at Glu-X bonds by the Staphylococcus aureus V8 protease. The sequence of the COOH-terminal residues was determined using bovine carboxypeptidases A and B and amino acid analysis. The histidine binding protein was found to contain 238 amino acid residues and to have a molecular weight of 26,104 calculated from sequence.

Amino Acid Sequence↗
PubMed1981

High-affinity arabinose transport mutants of Escherichia coli: isolation and gene location.

The gene araF, the product of which is the L-arabinose-binding protein--a component of the high-affinity L-arabinose transport system, was located on the Escherichia coli linkage map at 45 min. We established this location using bacteriophage P2 eductates and bacteriophage P1 cotransduction frequencies with the adjacent genetic loci, his (histidine biosynthesis) and mgl (methylgalactoside transport). In addition, we isolated a number of mutants that phenotypically exhibited altered high-affinity L-arabinose transport capacities. At least two of these mutations were located in the araF gene, as binding protein purified from these strains exhibited altered in vitro arabinose-binding properties.

Arabinose↗
PubMed1980

The NH2-terminal sequence of a precursor form of the arabinose binding protein.

Cell-free arabinose binding protein (ABP) was synthesized using a mRNA-directed Escherichia coli S30 translation system. The source of the mRNA was a total cellular RNA extract from cultures of E. coli B/r ara A 39, induced for ABP production. Purification of in vitro ABP was effected by affinity chromatography on a column of purified anti-ABP coupled to Sepharose 4B, followed by Sephadex G-75 chromatography in 9% formic acid. The purified in vitro ABP was found to have a molecular weight approximately 3000 greater than native ABP. Comparison of the CNBr peptide fragments of native and in vitro ABP demonstrated an NH2-terminal extension of 23 amino acids not present in native ABP. The identities of 20 of the residues in the extension were established, and the characteristics of this region resemble the features proposed for signal sequences that function in protein secretion.

Amino Acid Sequence↗
PubMed1980

Amino acid sequence of the sulfate-binding protein from Salmonella typhimurium LT2.

The amino acid sequence of the sulfate-binding protein from Salmonella typhimurium LT2 was determined by automated sequenator analysis of whole protein and fragments derived by chemical and enzymatic cleavage of whole protein. The fragments were products of limited trypsin digestion at arginine, cleavage at tryptophan by BrNps-skatole and o-iodosobenzoic acid, digestion with the protease from Staphylococcus aureus V8 at Glu-X bonds, cleavage by hydroxylamine at Asn-Gly bonds, and subdigestion with trypsin, chymotrypsin, and the Staphylococcus protease. The COOH-terminal sequence was confirmed using carboxypeptidase B and amino acid analysis. The sulfate-binding protein was determined to contain a single polypeptide of 310 residues with a molecular weight of 34,667 calculated from the sequence.

Amino Acid Sequence↗
PubMed1977

Amino acid sequence of the L-arabinose-binding protein from Escherichia coli B/r.

The amino acid sequence of the L-arabinose-binding protein of Escherichia coli B/r was determined by sequenator analyses of reduced and S-pyridylethylated L-arabinose-binding protein and fragments derived by chemical and enzymatic cleavage of the native protein. The fragments were the products of cleavage by cyanogen bromide. BNPS-skatole, hydroxylamine, mild acid hydrolysis, limited trypsin digestion, chymotrypsin subdigestion, and subdigestion with Staphylococcus aureus protease V8. The COOH-terminal sequence was determined using bovine carboxypeptidases A and B and amino acid analyses. The L-arabinose-binding protein was determined to contain 306 amino acid residues, the sequence of which is presented below.

Amino Acid Sequence↗
PubMed1977

L-Arabinose transport and the L-arabinose binding protein of Escherichia coli.

The active accumulation of L-arabinose by arabinose induced cultures of Escherichia coli is mediated by 2 independent transport mechanisms. One, specified by the gene locus araE, is membrane bound and possesses a relatively "low affinity". The other, specified in part by the genetic locus araF, contains as a functional component the L-arabinose binding protein and functions with a "high affinity" for the substrate. The L-arabinose binding protein has been purified, partially characterized, crystallized, and sequenced.

Amino Acid Sequence↗