摘要:

SummaryStarting with a DNA fragment containing the galactose operonP2 promoter, we made a series of deletions that progressively replaced DNA sequences upstream of the transcription startpoint and determined their effects onP2 activity. The results show that specific sequences upstream of −32 are not important. Removal of the sequence 5′‐CACA‐3′ from −32 to −28 reducesP2 activity by 50%: longer deletions to −16 further reduce activity but do not remove the information specifying the transcription startpoint. DNA sequences between −32 and −16 atgalP2 assist the isomerization of RNA polymerase from closed to open complexes rather than contributing to the initial binding of RNA polymerase. The activity of galP2 in the absence of −35 region sequences is dependent on the sequence TG just upstream of the − 10 hexamer, TATACT: a mutation at −14 changing the TG sequence to TT totally inactivatesP2. However,P2 activity can be restored if the consensus −35 region sequence TTGACA is cloned 17 bp upstream of the −10 hexamer. Thus, for transcription initiation, the −10 hexamer, TATACT, must ‘cooperate’ with upstream sequences that may

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1988.tb00018.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

SummaryThree nodulation genes,nodL, nodMandnodN, were isolated fromRhizobium leguminosarumand their DNA sequences were determined. The three genes are in the same orientation as the previously describednodFEgenes and the predicted molecular weights of their products are 20105 (nodL), 65795 (nodM) and 18 031 (nodN.) Analysis of gene regulation using operon fusions showed thatnodL, nodMand nodN are induced in response to flavanone molecules and that this induction is nodD‐dependent. In addition, it was shown that the nodM andnodWgenes are in one operon which is preceded by a conserved ‘nod‐box’ sequence, whereas thenodLgene is in the same operon as the nodFE genes. DNA hybridizations using specific gene probes showed that strongly homologous genes are present inRhizobium trifoliibut notRhizobium melilotiorBradyrhizobium japonicum.A mutation withinnodLstrongly reduced nodulation of peas, Lens andLathyrusbut had little effect on nodutation ofViciaspecies. A slight reduction in nodulation ofVicia hirsutawas observed with strains carrying mutations innod

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1988.tb00019.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

SummaryPrevious work has demonstrated the expression of the cloned pilin gene ofPseudomonas aeruginosaPAK withinEscherichia coliand has pinpointed this protein's localization exclusively to the cytoplasmic membrane (Finlayet al., 1986). To define regions of the pilin subunit necessary for its stability and transport withinE. coli, we constructed six mutants of the pilin gene and studied their expression and localization using a T7 promoter system. Two of the mutants have either a 4‐ or 8‐amino‐acid deletion at the N‐terminus and both were stably expressed and transported primarily to the cytoplasmic membrane ofE. coli.The other four mutants are C‐terminal truncations having between 36 and 56 amino acids of the C‐terminal region of the unprocessed pilin. Studies with these truncated mutants revealed that only the first 36 residues of the unprocessed pilin subunit were required for insertion into theE. c

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1988.tb00020.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

SummaryAn α‐amylase gene (aml) ofStreptomyces limosusATCC 19778 was cloned inStreptomyces lividans66. S1mapping experiments identified anamltranscript 1.8 kb in length and the extracellular enzyme was estimated to be 59 kD in size, suggesting thatamlwas transcribed as a monocistronic mRNA species. Expression of the gene was induced by maltose (or maltodextrins) inS. Iimosusand whenamlwas cloned inS. lividans or Streptomyces coelicolorA3(2). InS. Iimosus, mannitol repressed aml expression while glucose had little or no effect; inS. lividansandS. coelicolorthe relative effects of the two sugars were reversed. Both induction and carbon‐source repression of aml expression appeared to occur at the level of transcriptional initiation. Glucose repression in S. coelicolor was dependent upon a functional glucose kinase

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1988.tb00021.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

SummaryTo investigate structural characteristics important for eukaryotic signal peptide function In vivo, a hybrid gene with interchangeable signal peptides was cloned into yeast. The hybrid gene encoded nine residues from the amino terminus of the major Escherichia coli lipoprotein, attached to the amino terminus of the entire mature B. coli β‐lactamase sequence. To this sequence were attached sequences encoding the non‐mutant E. coli lipoprotein signal peptide, or lipoprotein signal peptide mutants lacking an amino‐terminal cationic charge, with shortened hydrophobic core, with altered potential helicity, or with an altered signal‐peptide cleavage site. These signal‐peptide mutants exhibited altered processing and secretion in E. coli. Using the GAL10 promoter, production of all hybrid proteins was induced to constitute 4–5% of the total yeast protein. Hybrid proteins with mutant signal peptides that show altered processing and secretion in E. coli, were processed and translocated to a similar degree as the non‐mutant hybrid protein in yeast (approximately 36% of the total hybrid protein). Both non‐mutant and mutant signal peptides appeared to be removed at the same unique site between cysteine 21 and serine 22. one residue from the E. coli signal peptidase II processing site. The mature lipo‐β‐lactamase was translocated across the cytoplasmic membrane into the yeast periplasm. Thus the protein secretion apparatus in yeast recognizes the lipoprotein signal sequence in vivo but displays a specificity towards altered signal sequences which differs

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1988.tb00022.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

SummaryA region of the IncHl plasmid R27 has been found to share very close nucleotide sequence homology with the RepFIA replicon of F. This region has been located on a 1.6 kb segment of R27 plasmid DNA, and corresponds to ori‐2 and the E gene of F. The IncC repeat sequence region shows reduced homology, with the F repeats being an imperfect subset of a larger repeated sequence found in R27. The E gene homologue of R27 is able to initiate replication from the F ori‐2 sequence and to repress the E gene promoter of F. The results are consistent with the observed incompatibility behaviour of R27, and have a bearing on the specificity of interaction of E protein with its DNA‐binding

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1988.tb00023.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

SummaryExpression of Neisseria gonorrhoeae Protein II (P.II) is subject to phase variation and antigenic variation. The P.II proteins made by one strain possess both unique and conserved antigenic determinants. To study the mechanism of antigenic variation, we cloned several P.II genes, using as probes a panel of monoclonal antibodies (MAbs) specific for unique determinants. The DNA sequences of three P.II genes showed that they shared a conserved framework, with two short hypervariable (HV) regions being responsible for most of the differences among them. We demonstrated that unique epitopes recognized by the MAbs were at least partially encoded by one of the HV regions. Moreover, we found that reassortment of the two HV regions among P.II genes occurs, generating increased structural and antigenic variability in the P.II protein family.

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1988.tb00024.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

SummaryThe basic Yop2b protein, encoded by the virulence plasmid pIBI of Yersinia pseudotuberculosis, is produced under Ca2+‐deficient conditions. A mutant deleted for the entire yopH gene, which encodes the Yop2b protein, was found to be avirulent. Virulence could be restored by trans‐complementation. The DNA‐Sequence of yopH predicted a 50 737 D polypeptide lacking a typical signal peptide. Transcription of yopH is regulated by both temperature and Ca2+‐concentration. Mutations within the region of the virulence plasmid known to be involved in regulating gene expression in response to Ca2+abolished transcription of yopH. Other temperature‐sensitive mutations in the Ca2+‐regulatory locus showed a high level of transcription regardless of Ca2+‐concentration. These responses were similar to those of the yopE gene. The promoter region of the yopE and yopH genes were compared and four conserved moti

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1988.tb00025.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

SummaryThe gene encoding pectin methyl esterase (pme) has been cloned from Erwinia chrysanthemi B374. Expression ofpmein Escherichia coli allowed the enzyme to be characterized. Pectin methyl esterase (PME) was found to have an apparent molecular weight of 36000 Daltons and an isoelectric point of approximately 9.9. The structural gene was sequenced and consists of a 1098‐bp open reading frame encoding a polypeptide of 39318 Daltons, which includes an amino‐terminal signal peptide. The isolation of the Erwinia gene provides a simple method for the production of PME free from depolymerizing pectinases thereby extending its potential u

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1988.tb00026.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

SummaryUropathogenic Escherichia coli frequently express P‐pilus adhesins that recognize Galα(1–4)Gal‐containing glycoconjugates. The P‐pilus adhesin of the,E. coliisolate J96 is encoded by the pap gene cluster and has been shown to agglutinate P1‐erythrocytes. We now describe a novel gene cluster from J96,prs, which is responsible for the agglutination of sheep erythrocytes. The structurally related gene clusters both expressed pili exhibiting the F13 antigen. Analysis of mutants of clonedprssequences, together withtrans‐complementation ofpapandprsgenes, identified the sheep‐specific adhesin as the 37‐kD PrsG protein. TheprsGgene occupies the equivalent position inprsas occupied bypapG, which specifies the Galeα(1–4)Gal‐specific adhesion ofpap.PrsG was shown to be structurally distinct from PapG since PapG‐specific antiserum did not cross‐react with PrsG. Using a solid phase glycolipid receptor binding assay, PrsG was found to specify preferential binding to the Forssman antigen, a major constituent of sheep erythrocyte membranes. The binding epitope was identified as the GaINAcα(1–3)GaINAc moiety. This is the first direct evidence that serologically identical pili may present antigenically distinct adhesins, each capable of bi

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1988.tb00027.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY