摘要:

SummaryWe have characterized a series of amber mutations in the A gene of bacteriophage Mu encoding the phage transposase. We tested different activities of these mutant proteins either in asup0strain or in differentsupbacteria. In conjunction with the results described in the accompanying paper by Bétermieret al.(1989) we find that theC‐terminus of the protein is not absolutely essential for global transposase function, but is essential for phage growth. Specific binding to Mu ends is defined by a more central domain. Our results also reinforce the previous findings (Bétermieret al., 1987) that more than one protein may be specified by theAg

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1989.tb00265.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryWe have generated a series of 3’deletions of a cloned copy of the bacteriophage Mu transposase (A) gene. The corresponding truncated proteins, expressed under the control of the λ Pl promoter, were analysedin vivofor their capacity to complement a superinfecting Mu4amphage, both for lytic growth and lysogeny, and for their effect on growth of wild‐type Mu following infection or induction of a lysogen. Using crude cell extracts, we have also examined binding properties of these proteins to the ends of Mu. The results allow us to further define regions of the protein important in replicative transposition, establishment of lysogeny and DNA bin

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1989.tb00266.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryMutants ofEscherichia colidefective in themdoAlocus are blocked at an early stage in the biosynthesis of membrane‐derived oligosaccharides. ThemdoAlocus has now been cloned into multicopy plasmids. A 5kb DNA fragment is necessary to complementmdoAmutations. Cells harbouring themdoA+plasmid produced three to four times more MDO than wild‐type cells. MDO overproduction did not affect the degree of MDO substitution with sn‐1‐phosphoglycerol residues. The biosynthesis of MDO remained under osmotic control in overproducing

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1989.tb00267.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryA collection of transposon‐induced mutants ofRhizobium meliloti1021 defective in siderophore‐mediated iron assimilation were obtained and classified as biosynthetic, transport or regulatory. Several of the mutations were cloned and the adjacent sequences were used to acquire complementing DNA from the wild type. A single genomic region of about 35kb complemented all of the mutants deficient in production of the sideroph

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1989.tb00268.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryThe 7kb virulence Region‐2 of the large (virulence) plasmid inShigella flexneri2a encodes several proteins required for invasion of intestinal epithelial cells. Insertion and deletion mutagenesis, DNA subcloning and SDS‐polyacrylamide gel electro‐phoresis of proteins synthesized in minicells demonstrated five genes in this region. They encode 24, 18, 62 (lpaB), 41 (lpaC) and 37 (lpaD)‐kiloDalton (kD) proteins. Complementation of Tn5‐induced mutations in Region‐2 with the above plasmid constructs indicated that Region‐2 consists of two operons and that the three lpa proteins are essential for the virulence phenotype. The transcriptional organization determined by Northern blotting, S1 nuclease protection and the effect of Tn5insertions on expression of the lpa proteins revealed that Region‐2 has three promoters that transcribe RNAs of 4.0, 4.5 and 7.5kb. The 4.0 kb RNA was the transcript for the operon encoding the 24, 18 kD, lpaB and C proteins and the 4.5 kb RNA for the ipsD gene. In addition, the full‐length RNA of 7.5 kb which covers Region‐2 supplemented full expression of the lpa proteins. The 7663 nucleotides of Region‐2 were determined to confirm the five open reading frames encoding 23655, 17755, 62168, 41077 and 36660 Dalton proteins, respectively, and their

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1989.tb00269.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryThe DNA‐binding AbrB protein ofBacillus subtilisis an ambiactive transcriptional regulator of genes expressed during the transition state between vegetative growth and the onset of stationary phase and sporulation. Studies on the transcriptional control of AbrB synthesis usingabrB‐lacZfusions indicated that theabrBgene was autoregulated. This was consistent with the observation that purified AbrB protein bound specifically to the promoter region of its own gene in DNase I protection experiments. The structural gene mutationabrB4abolished the autoregulatlon and purified AbrB4 protein did not have the promoter binding properties associated with the wild‐type protein. Both AbrB and AbrB4 proteins were shown to be hexamers of 10500 Dalton subunits and subunit exchange occurred between the proteinsin vitro.However, the presence of only one or two mutant subunits dramaticaly altered the DNA‐binding ability of the multimeric protein. The results support a model in which autoregulation of theabrBgene is an important factor in preventing sporulation‐associated genes from being expressed during vegetati

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1989.tb00270.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryThe complete nucleotide sequence of thexynAgene coding for a xylanase (XYLA) expressed byPseudomonas fluorescenssubspeciescellulosa, has been determined. The structural gene consists of an open reading frame of 1833 bp followed by a TAA stop codon. Confirmation of the nucleotide sequence was obtained by comparing the predicted amino acid sequence with that derived byN‐terminal analysis of purified forms of the xylanase. The signal peptide present at theNterminus of mature XYLA closely resembles signal peptides of other secreted proteins. Truncated forms of the xylanase gene, in which the sequence encoding theN‐terminal signal peptide had been deleted, still expressed an enzyme which was secreted inEscherichia coli.XYLA contains domains which are homologous to an endoglucanase expressed by the same organism. These structures include serine‐rich sequences. Bal31 deletions ofxynArevealed the extent to which these conserved sequences, in XYLA, were essential for xylanase activity. Downstream of the TAA stop codon is a G + C‐rich region of dyad symmetry (δG = 24kcal) characteristic ofE. coliRho‐independent transcription t

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1989.tb00271.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryComplementation for glucose transport capacity of deficient mutants fromSynechocystisPCC6803 allowed the cloning of the corresponding gene,glcP.The protein predicted from one open reading frame (ORF) in the DNA sequence was 468 residues long. It showed 46–60% amino acid sequence homology and similarity in size and predicted structure (including twelve probable membrane‐spanning regions) with a group of non‐phosphorylating sugar transporters from mammals, yeasts andEscherichia coli.A second ORF, 64 base pairs downstream fromglcP, was detected. Its function, dispensable under auto‐ and heterotrophic conditions, could not be determined. Genetic analysis of mutants confirmed that the resistance to fructose, acquired simultaneously with the deficiency in glucose transport, resulted from mutations in theglcPgene, whose approximate location could be det

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1989.tb00272.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryShiga toxin is a potent protein toxin produced byShigella dysenteriaetype I strains. In this report we present a procedure for the separation of functionally intact toxin A and B chains and for their reconstitution to form biologically active molecules. In agreement with the findings of others, the isolated A chain was shown to be a potentin vitroinhibitor of eukaryotic protein synthesis. The isolated B chain bound to HeLa cells and competitively inhibited the binding and cyto‐toxic activity of holotoxin. These findings show that the functional role of the B chain is to recognize cell surface functional receptors. By labelling the B sub‐unit alone, prior to renaturatlon of holotoxin, the polypeptide chains were shown to associate non‐covalently with a stoichiometry of one A chain and five B c

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1989.tb00273.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryWe have determined the complete nucleotide sequence of a 4.8 kilobase fragment encompassing thevirAlocus of the nopaline‐type plasmid, pTiC58, ofAgrobacterium tumefaciens. virAis composed of a single open reading frame of 2499 nucleotides, capable of encoding a protein of 91.3 kiloDaltons. AtrpE::virAgene fusion was used to confirm the reading frame ofvirA.High nucleotide and amino acid sequence homologies were observed between pTiC58virAand thevirAsequences of three octopine‐type plasmids. Strong homologies in amino acid sequence were observed between pTiC58 VirA and seven bacterial proteins which control various regulons. Two hydrophobic domains within VirA are also consistent with a model in which VirA acts as a membrane‐bound sensor of plant signal mole

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1989.tb00274.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY