摘要:

SummaryThe proteins present in gas vesicles of the cyanobacteriaAnabaena flos‐aquaeandMicrocystissp. Were separated by SDS‐polyacrylamide gel electrophoresis. Each contained a protein of Mr22 K whose N‐terminal amino acid sequences showed homology with that of theCalothrixsp. PCC 7601 gvpC gene product. The gvpC gene from A.flos‐aquaewas cloned and sequenced. The derived amino acid sequence for the gene product indicated a protein, GVPc, of 193 residues and Mr21985 containing five highly conserved 33 amino acid repeats. The sequence was identical at the N‐terminus to that of the Mr22K protein present in gas vesicles and showed correspondence to seven tryptic peptides isolated from gas vesicles. This establishes that GVPc forms a second protein component of the gas vesicle, in addition to the main constituent, the 70 residue GVPa. Quantitative amino acid analysis of entire gas vesicles reveals that GVPc accounts for only 2.9% of the protein molecules and 8.2% of the mass present: this is insufficient to form the conical end caps of the gas vesicles. It is suggested that GVPc provides the hydrophilic outer surface of the gas vesicle wall; the 33 amino acid repeats may interact with the periodic structure provide

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1988.tb00062.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

SummarySeveral overlapping carboxy‐terminal and internal deletions were constructed in the cloacin structural gene. The expression, the binding of the cloacin DF13 immunity protein and the release into the culture medium of the mutant cloacin polypeptides were studied by immunoblotting and ELISAs. Minor alterations at the carboxy‐terminal end of the cloacin did not affect protein expression, stability or release to a large extent, but larger carboxy‐terminal deletions strongly destabilized the protein and no release was observed. The removal of a particular region within the carboxy‐terminal portion of cloacin strongly destabilize the polypeptide and made it a target for proteolytic degradation. Binding of immunity protein did not affect stability and release of the mutant polypeptides. By using immunoelectron microscopy, the polypeptides that were not exported were located in the cytoplasm of producing cells. Large aggregates of these mutant polypeptides were not observed in the cytoplasm: the polypeptides were present in a solub

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1988.tb00063.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

SummaryInternal deletions close to the C‐terminus of the Escherichia coli penicillin binding protein 5 (PBP5, DacA) have defined the C‐terminal 18 residues of the protein as essential for membrane binding. This C‐terminal sequence is capable of forming a strongly amphiphilic α‐helix. In this paper we show that the PBP5 amphiphilic helix is able to anchor the periplasmic TEM‐β‐lactamase to the inner membrane. In addition, we have demonstrated that mature PBP5 (lacking the N‐terminal signal sequence) possesses the ability to bind to the membrane from a soluble form of the protein, showing that translocation across the membrane is unnecessary for anchoring to

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1988.tb00064.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

SummaryThe nucleotide sequence of 2.5 kb of the Streptomyces coelicolor A3(2) rRNA gene setrrnD, extending from upstream of the 16S rRNA gene to the putative 5′ end of the 23S rRNA gene, has been determined (Baylis and Bibb, 1987; this paper). In addition to locating the 5′ end of the 16S rRNA gene, nuclease S1mapping identified seven RNA 5′ end‐points upstream of the 16S rRNA gene; four of these were coincident with transcriptional initiation points for S. coelicolor A3(2) RNA poiymerase in vitro and were consequently regarded as in vivo transcription start points for promoters p1 to p4. One end‐point identified by nuclease S1mapping localized a putative processing site analogous to those found upstream of 16S rRNA genes in other eubacteria. Sequence motifs similar to those discovered in low G+C Gram‐positive bacteria were found associated with two of the promoters and the processing site. A probable protein coding region was observed upstream of the prom

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1988.tb00065.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

SummaryEight independent temperature‐sensitive mutants of the cell division protein FtsA have been studied. They fall into two classes in terms of their behaviour at 42°C and recovery at 30°C. The first class shows salt dependent temperature‐sensitivity and reversible in activation of FtsA protein at 42°C. The second shows irreversible inactivation which is not prevented by salt. Recovery of the ability to divide at 30°C is rapid in mutants of the first group, but is delayed for approximately a generation time in the second group. This suggests that irreversible inactivation of FtsA causes extensive damage to the division machinery. The amino acid substitutions show clustering to a limited domain of the protein, and one particular substitution is found in three of the

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1988.tb00066.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

SummaryOn the virulence plasmid ofShigella flexnerithevirGregion required for cell‐to‐cell spread of the bacteriumencodes a 130 kiloDalton (kD) antigen and Region‐2essential for the bacterial invasion of epithelial cells encodes 57, 43 and 39 kD antigens. The expression of these four antigens is positively regulated by the 30 kD protein encoded byvirF, whose nucleotide sequence had been determined and which was previously found to be essential for virulence. An approximately 3.8kilobase (kb) RNA transcript is found to be transcribed by thevirGregion and is positively regulated by thevirFprotein resulting in increased production of the 130 kD antigen. ThevirFsequence is conserved among all shigellae and enteroinvasiveEscherichia

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1988.tb00067.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

SummaryFourNeurospora crassagenomic clones have been selected as hybridizing much more strongly to labeled mRNA isolated from acetate‐grown mycelium than to mRNA from sucrose‐grown mycelium. Hybridization of restriction fragments with acetate‐specific mRNA or cDNA has been used to delimit the transcribed region(s) of each clone. The transcription of all four clones is strongly induced by transfer of growing mycelium from sucrose to acetate as sole carbon source. In wild‐type mycelium, mRNAs corresponding to the four clones reach maximum levels after four hours of induction. They accumulate more rapidly and reach higher levels in an acetate non‐utilizing mutant,acu‐7, which has been found to overproduce enzymes of the glyoxylate cycle and to have a partial block in the TCA cycle. Molecular transformation of aNeurosporaacu‐5mutant and of anAspergillus nidulans acuEmutant by DNA of clone 2 and clone 1, respectively, strongly suggests that clone 2 codes for acetyl‐coenzyme A synthetase and that clone 1 codes for malate synthase. The transcribed segments of clones 1 and 2each hybridize to corresponding clones fromAspergillusnidulans(R. A. Sandeman and M. J. Hynes, personal

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1988.tb00068.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

SummaryExpression of a 4kb segment of the bacteriocinogenic plasmid, plP404, fromClostridium perfringensinducible by UV‐irradiation. DNA sequence analysis revealed that this region contains three genes:uviA, uviBandbcnencoding the bacteriocin BCN5. Biochemical studies with mRNAs showed that expression was controlled at the transcriptional level and that the genes were organized in two independent transcriptional units,uviABandbenboth directed by tandem promoters inducible by UV light. Thebcngene is transcribed from three promoters (P1, P2, P3) while transcription ofuviABis directed by two promoters (P4, P5). With the exception of P4, which bears some resemblance to the consensus eubacterial promoter sequence, none of these promoters was recognizedinvitroby the major forms of RNA polymerase fromC. perfringens, Bacillus subtilisorEscherichia coli, Promoters P1, P3 and P5, which show striking homology with each other, contain unusual sequences in the ‘−35’ and ‘−10’ regions known to be recognized by RNA polymerase and this might indicate pos

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1988.tb00069.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

SummaryA new kanamycin‐resistance gene, detected inAcinetobacter baumanniiand designatedaphA‐6, was sequenced. It specifiesa 30319 Dalton 3′‐aminoglycosidephospliotransferase (APH(3′)) that mediates resistance to kanamycin and structurally related aminogiycosides, including amikacin. Pairwise comparisons of the six types of APH(3′) so far detected inhuman pathogens (types I, II, IM and VI) and in aminoglycoside‐producing microorganisms (types IV and V), confirm that APH(3) enzymes have diverged from a common ancestor. Three highly retained motifs (1:V–HGD—N; 2: G–D‐GR/K‐G and 3: D–K/R‐Y/F—LDE) located in the C‐terminal part of the enzymes were defined. Screening of protein sequence databases for each of these motifs revealed that motifs 1and 2 are both found in nucleotide‐binding phosphotransferases associated with a variety of biological processes, namely adenylate kinase, viral oncogenic protein kinases, elongation factors, Na+/K+‐transporting ATPase, myosin and antibiotic‐modifying enzymes. Motif 2 probably corresponds to the MgATP binding site, while motifs 3 and 1 could be involved in the splitting of the phosphodiester bond and in the phosphate transfer, respectively. Moreover, an additional motif, almost invariably centrally located, was found in all aminoglycoside‐modifying enzymes. The occurrence of this motif, possibly a recombination site which would have allowed the association of units of separate functions, is compatible with a modular concept for the struct

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1988.tb00070.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

SummaryWe have examined the topology of the yeast arginine permease, a plasma‐membrane protein with multiple membrane‐spanning domains. Using fusions of the permease with the glycosylatable secreted yeast protein, acid phosphatase, we identified membrane‐spanning sequences that can translocate adjacent acid phosphatase across the membrane of the endoplasmicreticulum (ER), as measured byin vitroglycosylation. Examination for the presence or absence ofglycosylation in a systematic series of such fusions gave an internally consistent model for the lumenat orcytoplasmic disposition of the acid phosphatase reporter, defining the topology of the permease. The phenotypes of a further set of arginine permease gene fusions with portions of the gene for the secreted protein, killer toxin, suggest that the pathways of export of membrane and secreted proteins need not be functionally dis

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1988.tb00071.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY