摘要:

SummaryWe show, using gel retardation, that crudeEscherichia colicell extracts contain a protein which binds specifically to DNA fragments carrying either end of the phage Mu genome. We have identified this protein as Fis, a factor involved in several site‐specific recombinational switches. Furthermore, we show that induction of a Mucte62 prophage in afislysogen occurs at a lower temperature than that of a wild‐type strain, and that spontaneous induction of Mucfs62 is increased in thefismutant. DNasel footprinting using either crude extracts or purified Fis indicate that binding on the left end of Mu occurs at a site which overlaps a weak transposase binding site. Thus, Fis may modulate Mu growth by influencing the binding of transposase, or other proteins, to the transposase binding site(s), in a way similar to its influence on Xis binding in phag

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1989.tb00192.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryThe nucleotide sequence has been determined for theStreptococcus mutanswall‐associated protein A (wapA) gene from serotype c strains Ingbritt and GS5. The nucleotide sequence for eachwapAgene was virtually identical, although the gene from strain GS5 contained a 24 base pair deletion. A 29 amino acid signal peptide was specified by eachwapAgene with a mature protein of 424 amino acids (Mr, 45276) for strain Ingbritt and 416 amino acids (Mr, 44846) for strain GS5. In theC‐terminal region of the wall‐associated protein A, considerable sequence similarity was found with the membrane anchor region of proteins from other Gram‐positive organisms such as the group A streptococcal M protein and the group G streptococcal IgG binding protein. Adjacent to the proposed membrane anchor is a highly hydrophilic region which may span the cell wall; both sequence data and experimental evidence indicate the existence of a region immediately outside the wall at which proteolytic cleavage occurs to release antigen A ofMr29000 into the culture supernatant. Thus, the wall‐associated protein A is a precursor of the 29000Mr

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1989.tb00193.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryTheospAandospBgenes encode the major outer membrane proteins of the Lyme disease spirochaeteBorrelia burgdorferi.The deduced translation products from theospAandospBgenes were: (OspA) 273 amino acids long with a molecular weight of 29334, and (OspB) 296 amino acids long with a molecular weight of 31739. The two Osp proteins showed a great degree of sequence similarity indicating a recent evolutionary event. Molecular analysis and sequence comparison of OspA and OspB with other proteins revealed a sequence similarity to the signal peptides of prokaryotic lipoproteins. These are the first sequences fromBorreliaand provide interesting data on the evolutionary relationship between spirochaetes and other species as well as providing potential for spirochaete diagnostics and vaccines.

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1989.tb00194.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryCells of the thermoacidophilic bacteriumBacillus acidocaldariusexpress a high‐affinity K+‐uptake system when grown at low external K+. A vanadate‐sensitive, K+‐ and Mg2+‐stimulated ATPase was partially purified from membranes of these cells by solubilization with a non‐ionic detergent followed by ion‐exchange chromatography of the extract. Combinations of non‐denaturing and denaturing electrophoretic separation methods revealed that the ATPase complex consisted of three subunits with molecular weights almost identical to those of the KdpA, B and C proteins, which together form the Kdp high‐affinity, K+‐translocating ATPase complex ofEscherichia coli.The affinity of the partially purified ATPase fromB. acidocaldariusfor its substrates K+(Km2–3 μM) and ATP (Km80 μM), its stimulation by various divalent cations, and its inhibition by vanadate (Ki1–2 μM), bafilomycin A1(Ki, 20 μM), DCCD (Ki200 μM) or Ca2+were also similar to those of theE colienzyme, indicating that the two K+‐translocating ATPases ha

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1989.tb00195.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryKlebsiella pneumoniaestrain PAP996 was previously shown to secrete fatty acylated, aggregated (micellar) pullulanase only after the end of exponential growth. Here we show that the closely related strain K21 secretes large amounts of unacylated, non‐aggregated (monomeric) pullulanase during exponential growth. Only a small amount (<10%) of the secreted pullulanase was initially retained by the exponentially growing cells to be subsequently secreted in a fatty acylated, aggregated form. Despite the absence of fatty acids in secreted monomeric pullulanase, the effects of the antibiotic globomycin on pullulanase maturation indicated that all of the enzyme synthesized by strain K21 is processed by lipoprotein signal peptidas

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1989.tb00196.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryThe DNA sequence of a 3.6kb region downstream of thenagBgene (encoding glucosamJne‐6‐PO4‐deaminase) inEscherichia colihas been determined. Three open reading frames, which are subsequently referred to asnagA, nagCandnagD, were detected in this sequence. Genetic complementation and enzyme assays have shown that the first of these,nagA, encodesN‐acetylglucosamine‐6‐phosphate deacetylase. Growth onN‐acetylglucosamine induces the synthesis of a 1900 nucleotide long transcript which covers justnagE, encoding EIINagwhich is transcribed divergently fromnagB, and of a 4200 nucleotide long transcript which covers all four ORFs of thenagB, A, C, Doperon. More mRNA corresponding tonagBandnagAis detected than that corresponding to the distal genes,nagCandnagD.Considerable amounts of the induced mRNA are truncated molecules having their 3’ends afternagBand afternagA.Multiple 3′ RNA ends have been mapped afternagDand seem to correspond to the ends of transcripts stabilized by mRNA secondary structure (REP sequences) rather than transcription termination sites. A second promoter producingnapD‐specific transcripts has been mapped just in f

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1989.tb00197.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryThe Yop proteins ofYersiniaare important virulence determinants. The Yop1 protein sequences ofYersinia pestis, Yersinia pseudotuberculosis, and twoYersinia enterocoliticaserotypes, O:3 and O:8, deduced from the nucleotide sequences of the correspondingyopAgenes, were compared. Most differences were found in the hydrophilic domains of the proteins, whereas the hydrophobic domains were conserved. The amino acid sequences revealed a signal sequence 25 amino acids long. No cysteine residues were present, even though Yop1 forms a polymeric structure.The transcription startpoint ofyop4was determined by primer extension. The coding region and transcription startpoint were separated by a leader sequence 270 nucleotides long. TheyopApromoter sequence ofY. pestisis identical to the corresponding sequence ofY. pseudotuberculosisand transcription studies revealed that this promoter is active inY. pestis.Thus, the inability ofY. pestisto express the Yop1 protein is due to a single base pair deletion In the coding region of theyopAgene ofY. pestis(Rosqvistet al., 1988).

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1989.tb00198.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryThe level of DNA supercoiling is crucial for many cellular processes, Including gene expression, and is determined, primarily, by the opposing actions of two enzymes: topoisomerase I and DNA gyrase.Escherichia colistrains lacking topoisomerase I (topAmutants) normally fail to grow in the absence of compensatory mutations which are presumed to relax DNA. We have found that, in media of low osmolarity,topAmutants are viable in the absence of any compensatory mutation, consistent with the view that decreased extracellular osmolarity causes a relaxation of cellular DNA. At higher osmolarity most compensatory mutations, as expected, are in thegyrAandgyrBgenes. The only other locus at which compensatory mutations arise, designatedtoc, is shown to involve the amplification of a region of chromosomal DNA which includes thetolCgene. However, amplification oftolCalone is insufficient to explain the phenotypes oftocmutants.tolCinsertion mutations alter the distribution of plasmid topoisomersin vivo.This effect is probably indirect, possibly a result of altered membrane structure and an alteration in the cell's osmotic barrier. AstolCis a highly pleiotropic locus, affecting the expression of many genes, it is possible that some of the TolC phenotypes are a direct result of this topological change. The possible relationship betweentoeandtolCmutations, and the means by whichtolCmutations might affect DNA supercoiling, are discussed.

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1989.tb00199.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryTwo regions of homology toAnabaena nifH(nitrogenase Fe protein) were detected in the total DNA of the thermophilic nitrogen‐fixing archaebacteriumMethanococcus thermolithotrophicus.A 2.8 kbHindlllfragment carrying one of these regions was previously cloned and shown to contain anifHgene (Souillardet al., 1988) now referred to as 0RFnifH2.A 3.4kbPstlfragment and an overlapping 3.B kbBglUfragment, containing the second region of homology, were cloned, and a DNA region of 4073bp was sequenced. It contained four complete open reading frames (ORFs) (ORFnifH1, ORF105, ORF128, ORFnifD) and two truncated ORFs (ORFnifK and ORF96). Five ORFs were transcribed in the same direction in the order of ORFnifH1‐ORF105‐ORF128‐ORFnifD‐ORFnifK.ORFnifH1, ORFnifDand ORFnifKwere assigned from their similarity to eubacterialnifHandnifDK(nitrogenase MoFe protein) genes. Transcription studies showed thatORFnifH1and ORFnifDwere expressed only under nitrogen‐fixation conditions, whereas no ORFnifH2mRNA was detected under the same conditions. A DNA probe containing ORFnifH1hybridized with a 1.8 kb mRNA, as detected by a Northern blotting experiment. A transcriptional start site was localized 87 and 88 bp upstream from the ATG codon of ORFnifH1, This site is preceded, 21 bp upstream, by the sequence 5′‐TTTATATA‐3′ already found at the same position in several archaebacterial promoters. ORFnifH1mRNA was too small to encode ORFnifDK.This was confirmed by the fact that another transcription start site was localized 85bp upstream from the

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1989.tb00200.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryThe proline catabolism gene cluster ofAspergillus nidulanswas cloned using a ‘brute force’ technique which detects clones hybridizing to restriction fragments overlapping chromosomal rearrangements. A number of deletion mutations and a translocation mutation in the cluster have been physically mapped, and an excellent correlation between the genetic and physical maps was established. Transcripts have been identified and orientated for each of the four genes of the cluster. All are monocistronic by size. All of the transcripts, including that of the regulatory geneprnA, are inducible. Using deletion endpoints and mRNA sizes, approximate gene positions on the physical map have been determined. Finally, the relationship between genetic and physical distance across the cluster has been estimated at 3‐4 kilobases per centiM

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1989.tb00201.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY