摘要:

SummaryAs part of ongoing efforts to Investigate the molecular biology of the human pathogens in the genusMycobacterium, a customized database was developed specifically for these organisms and implemented in ACEDB database manager software. The data loaded include the IMMYC Antigen List, details of reagents available from the CDC/WHO Antibody Bank, more than 1 Mb of sequences of mycobacterial genes and proteins from public databases, the physical maps ofMycobacterium lepraeandMycobacterium tuberculosisdeveloped at the institut Pasteur, as well as a subset of the references found in MedLine. The ACEDB software allows both quick and intuitive access to the data and to connections between facts by a simple mouse‐driven interface, as well as by more powerful query mechanism

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1994.tb01039.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

SummarylytD, the structural gene of theBacillus subtilis168N‐acetylglucosaminidase was localized at 310°, next to thetagABCoperon. Sequence analysis revealed a monocistronic operon encoding a 95.6 kDa protein endowed with an export signal, the cleavage of which yields the monomer polypeptide (92.8 kDa) of the dimeric active form of the enzyme. Transcription is initiated at a sigma‐D (σD)‐dependent promoter and ends at a terminator common tolytDand the divergently transcribedtagABCoperon. In addition, we report the sequence of the adjacent upstream ORF, transcribed in the same direction aslytD, which shows significant homology to phosphomannose isomerase‐encoding genes. Cell separation, motility, autolysis, cell wall turnover and growth were not affected in strains devoid of theN‐acetylglucosaminidase. A mutant deficient in the two most abundant autolysins, i.e. the LytC amidase and the glucosaminidase, exhibited the phenotype of the amidase‐deficient strains, revealing their non‐requirement for growth. This conclusion raises two fundamental questions: how does the cell undo the highly cross‐linked peptidoglycan so as to be able to grow, and what is the rote of the considerable amount of autolysin normally present? Possible answers to these questi

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1994.tb01040.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

SummaryAn invertible DNA element of 6.8 kb, designated the hsd1 locus, was identified in the chromosome ofMycoplasma pulmonis.Infection of host cells with mycoplasma virus P1 revealed that the organism's restriction and modification (R‐M) properties are controlled by inversion ofhsd1.The nucleotide sequence ofhsd1revealed several genes, the predicted amino acids of which bear striking similarity to the subunits of the type I R‐M enzymes previously found only in enteric bacte

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1994.tb01041.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

SummaryThe effect of distance between 18 bp direct repeats on deletion formation has been examined inBacillus subtilis.The deletion frequency decreased exponentially by more than 1000‐fold as the distance increased from 33 to 2313 bp. This decrease occurred in two distinct phases, which may be determined by DNA‐duplex flexibility. A similar relationship between deletion formation and distance was observed in a θ‐replicating plasmid and in the chromosome, indicating that this relationship might have a general va

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1994.tb01042.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

SummaryWe present evidence showing thatrpoS(katF) is a regulator ofkatGgene transcription In anoxyR‐independent manner. Mutation of therpoSgene in several differentEscherichia colistrains caused a significant reduction in catalase HPI activity. InrpoSδoxyRdouble mutants, the level of HPI was considerably lower compared to the δoxyRparent strain, and was restored when transformed with anrpoS+plasmid. Overproduction of HPI inoxyRsuppressor strains was greatly diminished after inactivation of therpoSgene and was accompanied by a substantial increase in sensitivity to menadione. Beta‐galactostdase expression from akatG::lacZpromoter was lower inrpoSstrains compared torpoS+isogenic parents. Several δoxyRstrains had detectable levels ofkatGtranscription that was significantly diminished afterrpoSgene inacti

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1994.tb01043.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

SummaryEscherichia colican use nitrate as a terminal electron acceptor for anaerobic respiration. A polytopic membrane protein, termed NarK, has been implicated in nitrate uptake and nitrite excretion and is thought to function as a nitrate/nitrite antiporter. The longest‐lived radioactive isotope of nitrogen,13N‐nitrate (half‐life = 9.96 min) and the nitrite‐sensitive fluorophore N‐(ethoxycarbonylmethyl)‐6‐methoxyquinolinium bromide have now been used to define the function ofNarK.At low concentrations of nitrate, NarK mediates the electrogenic excretion of nitrite rather than nitrate/nitrite exchange. This process prevents intracellular accumulation of toxic levels of nitrite and allows further detoxification in the periplasm through the action of nitr

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1994.tb01044.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

SummaryThe gene responsible for the optochin‐sensitive (OptS) phenotype ofStreptococcus pneumoniaehas been characterized. Sequence comparisons indicated that the genes involved encoded the subunits of the F0complex of an H+‐ATPase. Sequence analysis and transformation experiments showed that theatpCgene is responsible for the optochin‐sensitive resistant (OptS/OptR) phenotype. Our results also show that natural as well as laboratory OptRisolates have arisen by point mutations that produce different amino acid changes at positions 48, 49 or 50 of the ATPase c subunit. The nucleotide sequence of the F F0complex of theStreptococcus oralisATPase has also been determined. In addition, comparison of the sequence of theatpCABgenes ofS. pneumoniaeR6 (OptS) and M222 (an OptRstrain produced by inter‐species recombination between pneumococcus andS. oralis), andS. oralisrevealed that, in M222, an interchange ofatpCandatpAhad occurred. We also demonstrate that optochin specifically inhibited the membrane‐bound ATPase activity of theS. pneumoniaewild‐type (OptS) strains, and found a 100‐fold difference between OptSand OptRstrains, both in growth inhibition and in membrane ATPa

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1994.tb01045.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

SummaryStaphylococcus aureushas been shown to interact specifically with fibrinogen. Three different extracellular fibrinogen‐binding proteins, two of which have coagulase activity, are produced byS. aureusstrain Newman. The role of these fibrinogen‐binding proteins during staphylococcal colonization and infection has not yet been fully elucidated. Here we describe the cloning, sequencing and expression of a gene for a 19kDa fibrinogen‐binding protein. This gene, calledfib, encodes a 165‐amino‐acid polypeptide, including a 29‐amino‐acid signal sequence. The recombinant protein, which has an estimated molecular mass of 15.9kDa, bound fibrinogen and was recognized by a polyclonal antiserum against the native Fib protein. Homologies between the Fib protein and the fibrinogen‐binding domain of coagulase suggest that amino acids within this domain are involved in the bindin

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1994.tb01046.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

SummaryRibosomal DNA sequences in several species of the genusEntamoebaare highly repeated and display restriction fragment‐length polymorphism (RFLP), which has been used to identify species and differentiate strains. However, the continuous variability of the non‐transcribed repeat sequences in the ribosomal episome hinders an accurate typification. Looking for more reliable markers, we used DNA probes containing conserved sequences in the ribosomal episome — coding regions for the 16S and 5.8S rRNAs and transcribed spacers flanking the rDNA sequences, and the coding region for the 3 end of the 26S rRNA — to analyse hybridization patterns from five cloned pathogenic strains ofEntamoeba histoiytica, two strains of the also pathogenicEntamoeba invadensand the non‐pathogenic Laredo strain ofEntamoeba moshkovskii.Our results provide reliable bases for the differentation of clones, strains and species ofEntamoebaand the reconstruction ofE. histolyticaepisomes. Differences in the number and length of rDNA‐containing DNA fragments, previously observed by other investigators and confirmed by us, can be better defined by the prese

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1994.tb01047.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

SummaryLactoferrin‐binding or ‐associated proteins were identified inTreponema pallidumsubspeciespallidumandTreponema denticolaby affinity column chromatography using human lactoferrin and detergent‐solubilized, radiolabelled spirochaetes. Two discrete polypeptides ofT. pallidumwith masses of 45 and 40kDa and a broad band from 29‐34 kDa exhibited association with human apo‐ and partially ferrated lactoferrin.T. denticolaproduced two proteins that associated with a lactoferrin affinity matrix (50 and 35 kDa).T. pallidumandT. denticoladid not associate with soluble, human transferrin in parallel experiments. Soluble human lactoferrin competed with all lactoferrin‐associated proteins fromT. pallidumandT. denticolain competitive‐binding assays. However, theT. denticolaproteins dissociated from a lacto‐ferrin‐affinity matrix in the presence of differing concentrations of unlabelled, soluble lactoferrin competitor. Treatment with phospholipase D altered migration of the diffuse 29‐34 kDa band ofT. pallidumsuggesting that the polypeptide was lipid‐modified. Each of the lactoferrin‐binding proteins fromT. pallidumandT. denticolareacted with pooled rabbit syphilitic antisera. The lactoferrin‐binding proteins ofT. pallidumreacted with human sera from patients at all stages of syphilis. In addition, a monoclonal antibody generated against the 45 kDa polypeptide ofT. pallidumcrossreacted w

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1994.tb01048.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY