bluuebunny/crossref_metadata_2025_split huggingface dataset:
Wolinella succinogenes fumarate reductase contains a dihaem cytochrome b
Authors: Körtner C. , Lauterbach F. , Tripier D. , Unden G. , Kröger A. 
Published: October 2006

SummaryThe fumarate reductase operon of Wolinella succinogenes is made up of three structural genes (frd‐CAB). The frdC gene was located next to the promoter region and identified as the cytochrome b structural gene encoding 256 amino acid residues. The N‐terminal amino acid sequences of seven fragments derived from the cytochrome b moiety of the enzyme all mapped within the frdC gene. This suggested that the enzyme contained only one species of cytochrome b. Re‐evaluation of earlier measurements of subunit composition, haem B content and molecular weight led to the conclusion that the enzyme contained one molecule of cytochrome b with two haem B groups. The hydropathy plot of the amino acid sequence predicted five membrane‐spanning hydrophobic segments, the first four of which contained a single histidine residue each. These residues could form the axial ligands to the two haem B groups. FrdC was found to be homologous with the cytochrome b (SdhC) of the Bacillus subtilis succinate dehydrogenase, but not with the hydrophobic subunits of the fumarate reductase or succinate dehydrogenase of Escherichia coli.
Intron‐associated splicing reactions in bacteriophage T4
Authors: Maley F. , Chu F. K. , Maley G. F. 
Published: October 2006

SummaryGroup I introns are present in at least three bacteriophage T4 genes: td, nrdB and sunY. The transcription products of these three genes have similar intron consensus regions and secondary structures, which render them capable of guanosine‐mediated in vitro autocatalytic splicing reactions. Moreover, it has been shown that the 245‐amino‐acid protein encoded in the td intron expresses an endonuclease that cleaves near the joining site for the two exons in the intron‐deleted thymidylate synthase gene. The intron‐containing td gene is resistant to the enzyme. As in the case of other group I intron‐containing genes that have been described in eukaryotes, which also encode site‐specific endonucleases, the td intron is highly mobile and can insert into the intronless td gene by a process initiated by endonuclease cleavage near the insertion site. Whether intron transposition reactions have any physiological significance to the phage, or represent an early imprint on the evolution of introns, remains to be determined.
Structure and function of haemolysin B, P‐glycoprotein and other members of a novel family of membrane translocators
Authors: Blight M. A. , Holland I. B. 
Published: October 2006

SummaryRecent studies have identified two sub‐families of highly conserved polypeptides in a wide variety of organisms concerned with the transport of many different compounds, specific for each transport protein. Both famines, represented by HisP and HlyB, respectively, have in common a highly conserved, approximately 25kD domain, containing an ATP‐binding site. The HisP sub‐family essentially consists of cytoplasmic proteins which couple energy to the import of small substrates through cytoplasmic membrane permeases in Gram‐negative bacteria. The HlyB (P‐glycoprotein) sub‐family, on the other hand, contains a second large domain which apparently acts as the transmembrane translocator itself, which in most cases drives the secretion of a variety of compounds. These membrane domains share a number of structural features which also serve to distinguish these proteins as a closely related group. Nevertheless, the compounds secreted by the HlyB sub‐family Include large polypeptides, polysaccharides and a variety of anti‐tumour drugs. We describe here the properties of each of these remarkable proteins and we speculate on their possible mechanism of action.
Homologous DNA sequences on the virulence plasmids of pathogenic Yersinia and Salmonella dublin Lane
Authors: Krause M. , Fierer J. , Guiney D. 
Published: October 2006

Summary Yersinia and Salmonella harbour plasmids that encode traits important for virulence, enabling both pathogenic genera to survive and grow in cells of the reticulo‐endothelial organs during systemic infections. We have detected DNA homology between the Salmonella dublin virulence plasmid pSDL2 and the plasmids of the pathogenic Yersinia species pestis, pseudotuberculosis, and enterocolitica. Three regions of pSDL2 were found to share homology with the virulence plasmid pIB1 of Yersinia pseudotuberculosis. Two separate hybridizing segments mapped within the previously characterized 6.4 kb vir region of pSDL2 in the Sal1 B fragment. The third homologous region involved the regions of plB1, which hybridized to the Sal1 C2 fragment of pSDL2. The virulence plasmid pCD1 from Y. pestis showed similar homology with the three regions of pSDL2. Homologies to the vir and Sal1 C2 regions of pSDL2 were also found on plasmids from Yersinia enterocolitica serotypes 0:9, 0:3 and 0:5, 27. The discovery of separate homologous regions on the virulence plasmids of Salmonella and Yersinia suggests a distant evolutionary relationship.
Tn552, a novel transposable element from Staphylococcus aureus
Authors: Rowland S.‐J. , Dyke K. G. H. 
Published: October 2006

SummaryTn552, one of several closely related β‐lactamase‐encoding transposons from Staphylococcus aureus, has a novel set of putative transposition functions. Each is homologous with a well‐characterized function from a different type of mobile genetic element. Thus, Tn552 encodes: (i) resL‐binL, a co‐integrate resolution system homologous with those of Tn3 family elements; (ii) p480, a potential transposase significantly homologous with the DNA integrases of eukaryotic retroviruses and retrotransposons; and (iii) p271, a potential ATP‐binding protein that shows homology with the B protein of phage Mu. The 3′terminal nucleotides of Tn552 (CA), adjacent to which p480 might cleave, are the same as those of retro‐viruses, retrotransposons and phage Mu. The presumptive resolvase (BinL) is very closely related to BinR, which was identified as a DNA invertase and is now shown to resolve an artificial co‐integrate in vivo. Furthermore, the structure of the derivative of Tn552 found in the staphylococcal plasmid pl258 can be explained by a BinL (or BinR)‐mediated site‐specific deletion (‘resolution’) event. Thus, pl258 contains only the right‐hand half of Tn552, which encodes the β‐lactamase and two regulatory proteins. The latter are homologous with the β‐lactamase gene repressor and co‐inducer of Bacillus licheniformis. Interestingly, the order of the regulatory genes is reversed in S. aureus compared with Bacillus licheniformis.
The Min DNA inversion enzyme of plasmid p15B of Escherichia coli 15T−: a new member of the Din family of site‐specific recombinases
Authors: Iida S. , Sandmeier H. , Hübner P. , Hiestand‐Nauer R. , Schneitz K. , Arber W. 
Published: October 2006

SummaryPlasmid p15B is a bacteriophage P1‐related resident of Escherichia coli 15T−. Both genomes contain a segment in which DNA inversion occurs, although this part of their genomes is not identical. This DNA segment of p15B was cloned in a multicopy vector plasmid. Like its parent, the resulting plasmid, pAW800, undergoes complex multiple DNA inversions: this DNA inversion system is therefore called Min. The min gene, which codes for the p15B Min DNA invertase, can complement the P1 cin recombinase gene. The Min inversion system is thus a new member of the Din family of site‐specific recombinases to which Cin belongs. The DNA sequence of the min gene revealed that Min is most closely related to the Pin recombinase of the e14 defective viral element on the E. coli K12 chromosome. Like other members of the Din family, the min gene contains a recombinational enhancer element which stimulates site‐specific DNA inversion 300‐fold.
The identification, characterization, sequencing and mutagenesis of the genes (hupSL) encoding the small and large subunits of the H2‐uptake hydrogenase of Azotobacter chroococcum
Authors: Ford C. M. , Garg N. , Garg R. P. , Tibelius K. H. , Yates M. G. , Arp D. J. , Seefeldt L. C. 
Published: October 2006

SummaryThe structural genes (hupSL) of the membrane‐bound NiFe‐containing H2‐uptake hydrogenase (Hup) of Azotobacter chroococcum were identified by oligo‐nucleotide screening and sequenced. The small subunit gene (hupS) encodes a signal sequence of 34 amino acids followed by a 310‐amino‐acid, 34 156 D protein containing 12 cysteine residues. The large subunit gene (hupL) overlaps hupS by one base and codes for a predicted 601‐amino‐acid, 66433 D protein. There are two regions of strong homology with other Ni hydrogenases: a Cys‐Thr‐Cys‐Cys‐Ser motif near the N‐terminus of HupS and an Asp‐Pro‐Cys‐Leu‐Ala‐Cys motif near the carboxy‐terminus of HupL. Strong overall homology exists between Azotobacter, Bradyrhizobium japonicum and Rhodobacter capsulatus Hup proteins but less exists between the Azotobacter proteins and hydrogenases from Desulfovibrio strains.Mutagenesis of either hupS or hupL genes of A. chrooooccum yielded Hup− phenotypes but some of these mutants retained a partial H2‐evolving activity. Hybridization experiments at different stages of gene segregation confirmed the multicopy nature of the Azotobacter genome.
Outer membrane proteins of Pseudomonas
Authors: Hancock R. E. W. , Siehnel R. , Martin N. 
Published: October 2006

SummaryIn this review, we describe the outer membrane proteins of Pseudomonas aeruginosa and related strains from the Pseudomonas fluorescens rRNA homology group of the Pseudomonadaceae, with emphasis on the physiological function and biochemical characteristics of these proteins. The use of opr (for outer membrane protein) is proposed as the genetic designation for the P. aeruginosa outer membrane proteins and letters are assigned, in conjunction with this designation, to known outer membrane proteins. Proteins whose primary functions involve pore formation, transport of specific substrates, cell structure determination and membrane stabilization are discussed. The conservation of selected proteins in the above Pseudomonas species is also examined.
Signal transduction and gene regulation through the phosphorylation of two regulatory components: the molecular basis for the osmotic regulation of the porin genes
Authors: Mizuno T. , Mizushima S. 
Published: October 2006

SummaryExpression of Escherichia coli outer‐membrane porin proteins (OmpF and OmpC) is regulated by the osmolarity of the medium. EnvZ and OmpR, which are positive regulatory factors for the transcriptional osmotic regulation of the ompF and ompC genes, belong to a group of two‐component regulatory factors that respond to a variety of environmental stimuli in bacteria. EnvZ‐OmpR phosphotransfer was revealed to be involved in signal transduction in response to an osmotic stimulus, and to play a crucial physiological role in the consequent osmotic activation of the porin genes. Based on the various lines of experimental evidence, a model is proposed for the molecular mechanism underlying the osmotic regulation through phosphorylation of the activator (OmpR) by the membrane‐locate kinase (EnvZ).
Characterization of a Listeria monocytogenes‐specific protein capable of inducing delayed hypersensitivity in Listeria‐immune mice
Authors: Göhmannn S. , Wächter M. Leimeister , Schiltz E. , Goebel W. , Chakraborty T. 
Published: October 2006

SummaryRecovery of the host after infection by the intracellular pathogen Listeria monocytogenes is dependent on cell‐mediated immunity. Little is known of the nature of listerial antigens that induce cell‐mediated responses in the infected host. In this study we report on the identification and cloning of an Escherichia coli recombinant encoding a listerial antigen, designated ImaA, capable of eliciting a specific delayed‐type hypersensitivity response in Listeria‐immune mice. Nucleotide sequencing of the Listeria DNA insert in plasmid pLM10 showed that the Ima A gene product consisted of 170 amino acids with a molecular weight of 17994. The predicted amino acid sequence suggests that the protein is localized to the bacterial plasma membrane or cell wall. The ImaA gene was unique to the pathogenic species L. monocytogenes and Listeria ivanovii; it was not present in any other species of the genus Listeria.
Streptococcus pneumoniae possesses canonical Escherichia coli (sigma 70) promoters
Authors: Morrison D. A. , Jaurin B. 
Published: October 2006

SummarySummary Seventeen DNA fragments from Streptococcus pneumoniae were randomly cloned in Escherichia coli with selection for promoter activity. The fragments were sequenced and the promoter locations were determined by primer extension analysis. Examination for sites similar to the E. coli major consensus promoter sequence revealed such a site in each of the seventeen fragments, located five to eight base pairs upstream of the point at which transcription was initiated in the E. coli host. Thus, the abundance of promoter activity found in pneumococcal DNA cloned in E coli hosts arises primarily from sigma‐70‐type promoter structures. Combined with the observation that such sequences are usually found just upstream of, but not within, pneumococcal genes, this implies that one class (perhaps the major class) of pneumococcal promoters closely resembles the canonical E. coli promoter consensus.
Isolation and characterization of the recA gene of Bordetella pertussis
Authors: Kuhl S. A. , McCreary R. P. , Bannan J. D. , Friedman R. L. 
Published: October 2006

SummaryThis report describes the detection and cloning of the Bordetella pertussis recA gene. Escherichia coli clones having recombinant plasmids containing the B. pertussis recA gene were isolated by complementing an E. coli RecA− mutant's inability to survive in the presence of methylmethanesulphonate (MMS). This gene was shown to complement the deficiency of E. coli RecA− strains to tolerate the DNA‐damaging effects of both a chemical agent and ultraviolet light (u.v.). Deletion mapping experiments localized the gene to a 2.5kb Stul‐EcoRI fragment, and expression of the gene in E. coli resulted in the production of a 40kD protein. These data strongly suggest that a region of the B. pertussis chromosome that encodes RecA‐like activity has been isolated and cloned.
Molecular mechanism for the antigonococcal action of lysosomal cathepsin G
Authors: Shafer W. M. , Onunka V. C. , Jannoun M. , Huthwaite L. W. 
Published: October 2006

SummaryHuman lysosomal cathepsin G (cat G) appears to be an important mediator of non‐oxidative killing of Neisseria gonorrhoeae ingested by human polymorpho‐nuclear leucocytes (PMNLs). Nearly isogenic strains of gonococci having variations in the structure of penicillin‐binding protein 2 (PBP2) also exhibit different levels of susceptibility to the lethal action of cat G in vitro. Accordingly, we examined the relationship between gonococcal susceptibility to cat G and PBP2 structure. The results of this study suggest that cat G has the capacity to interact with PBP2, as evidenced by its ability to inhibit binding of [3H]‐benzylpenicillin to PBP2. We also found that changes in the amino acid sequence within the transpeptidase domain of PBP2, because of certain penA mutations, modulated such interactions. We propose that PBP2 is an intracellular target for cat G and that levels of gonococcal susceptibility to cat G may be related to PBP2 structure and/or intracellular availability.
Mannose‐sensitive haemagglutination in the absence of piliation in Escherichia coli
Authors: Hultgren S. J. , Duncan J. L. , Schaeffer A. J. , Amundsen S. K. 
Published: October 2006

SummaryThe relationship between type 1 pilus structure and the mannose‐sensitive adhesin was investigated by analysing the properties of an 11.2 kb fragment of DNA derived from the chromosomal pil region of a type 1 piliated uropathogenic strain of Escherichia coli. The recombinant plasmids pHA9 and pSJH9, containing the cloned fragment, conferred a mannose‐sensitive haemagglutination (MSHA)‐positive but non‐piliated phenotype on recipient cells of ORN104. Most of the DNA sequences homologous to the pilA and hyp genes were not present in the 11.2kb insert, and the genetic information necessary for MSHA in the absence of piliation spanned a 6.5 kb region of the cloned fragment. The polypeptides expressed by pSJH9 were examined in minicells and Tn 1000 insertions in three genes encoding proteins of molecular weights 90 kD, 29 kD and 17kD abolished the MSHA phenotype.
Type V collagen as the target for type‐3 fimbriae, enterobacterial adherence organelles
Authors: Tarkkanen A.‐M. , Allen B. L. , Westerlund B. , Holthöfer H. , Kuusela P. , Risteli L. , Clegg S. , Korhonen T. K. 
Published: October 2006

SummaryTissue‐binding specificity of the type‐3 fimbriae of pathogenic enteric bacteria was determined using frozen sections of human kidney. A wild‐type Kleb‐siella sp. strain and the recombinant strain Escherichia coli HB101(pFK12), both expressing type‐3 fimbriae, as well as the purified type‐3 fimbriae effectively bound to sites at or adjacent to tubular basement membranes, Bowman's capsule, arterial walls, and the interstitial connective tissue. Bacterial adherence to kidney was decreased after collagenase treatment of the tissue sections. Recombinant strains expressing type‐3 fimbriae specifically adhered to type V collagen immobilized on glass slides, whereas other collagens, fibronectin or laminin did not support bacterial adherence. In accordance with these findings, specific binding of purified type‐3 fimbriae to immobilized type V collagen was demonstrated. Specific adhesion to type V collagen was also seen with the recombinant strain HB101(pFK52/pDC17), which expresses the mrkD gene of the type‐3 fimbrial gene cluster in association with the pap‐encoded fimbrial filament of E. coli, showing that the observed binding was mediated by the minor lectin (MrkD) protein of the type‐3 fimbrial filament. The interaction is highly dependent on the conformation of type V collagen molecules since type V collagen in solution did not react with the fimbriae. Specific binding to type V collagen was also exhibited by type‐3 fimbriae strains of Yeisinia and Salmonella, showing that the ability to use type collagen as tissue target is widespread among enteric bacteria.
Secretion of Ricinus communis glyceraldehyde‐3‐phosphate dehydrogenase by Escherichia coli
Authors: Hekman W. E. , Dennis D. T. , Miernyk J. A. 
Published: October 2006

SummaryA plasmid, pWEH1, was constructed containing a fusion of the DNA encoding the signal sequence of the Escherichia coli outer‐membrane protein A to the 5′‐end of a glyceraldehyde‐3‐phosphate dehydrogenase cDNA from Ricinus communis. When expressed in E. coli, the fusion protein was secreted by the normal membrane‐potential‐dependent pathway. Processing by signal peptidase was inhibited by low concentrations of phenethyl alcohol. Quantitative cell fractionation was used to show that the mature plant protein was associated with the bacterial outer membrane. The protein could not be released from the membrane by washing with alkaline sodium carbonate. Radioactivity from [U‐14C]‐palmitate was incorporated into the heterologous protein. These results suggest that the sequence of this normally cytoplasmic enzyme contains a cryptic lipid‐modification site, and the combination of a signal sequence plus a lipid‐modification sequence results in specific targeting to the bacterial outer membrane.
Purification and characterization of RNase P from Clostridium sporogenes
Authors: Roselli D. M. , Marsh T. L. 
Published: October 2006

SummaryRNase P is a multi‐subunit enzyme responsible for the accurate processing of the 5′ terminus of all tRNAs. The RNA subunit from Clostridium sporogenes has been partially purified and characterized. The RNA is approximately 400 nucleotides long and makes a precise endonucleolytic cleavage at the mature 5′ terminus of tRNA. The RNA requires moderate concentrations of Mg2+ (20mM) and relatively high concentrations of NH4Cl (800mM) for optimal activity. Mn2+ effectively substitutes for Mg2+ at 2mM. Zn2+, Ni2+, Ca2+, and Co2+ are ineffective at stimulating activity. Monovalent ions are, in general, more effective the greater the ionic radius (NH+4Cs>Rb>K>Na). In contrast to the activity of Bacillus subtilis, C. sporogenes RNase P RNA is significant more active in (NH4)2 SO4 than in NH4Cl.
Pyoverdin‐facilitated iron uptake in Pseudomonas aeruginosa: immunological characterization of the ferripyoverdin receptor
Authors: Meyer J. M. , Hohnadel D. , Khan A. , Cornelis P. 
Published: October 2006

SummaryA purified polyclonal antiserum directed against the isolated main 80kD IROMP (iron‐regulated outer‐membrane protein) from Pseudomonas aeruginosa PAO1 detected only the 80 kD polypeptide of outer‐membrane proteins from PAO1 cells grown in iron deficiency in Western blots. It was also shown to inhibit the uptake of 59Fe pyoverdin by PAO1 cells as well as its binding to purified outer membranes. Immunofluorescence experiments with intact PAO1 cells confirmed that the receptor is present only at the surface of cells grown under conditions of iron deficiency. All these data allow us to conclude that the 80 kD main IROMP of P. aeruginosa is indeed the receptor for the siderophore ferripyoverdin.
A rapid method for reconstitution of bacterial membrane proteins
Authors: Varadhachary A. , Maloney P. C. 
Published: October 2006

SummaryWe have devised a simple method for the reconstitution of bacterial membrane proteins directly from small (1–20 ml) volumes of cell culture, thus eliminating the preparation of membrane vesicles. Cells are subjected to simultaneous lysozyme digestion and osmotic lysis, and after brief centrifugation ghosts are solubilized in 1.2% octyl‐β‐D‐glucopyranoside (octyl‐glucoside) in the presence of added carrier lipid and an osmolyte. Aliquots of the clarified supernatant are suitable for reconstitution, as documented by using extracts from three different Gram‐negative cells to recover both inorganic phosphate (Pi)‐linked antiport and oxalate: formate exchange activities in proteoliposomes. These proteoliposomes are physically stable, non‐leaky and can sustain a membrane potential and, because functional porins do not reconstitute, the artificial system has transport characteristics similar to those found when proteoliposomes are obtained using standard methods. This method should become an important tool for the screening and characterization of large numbers of strains, both wild‐type and mutant.