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W F Coetzee

Publications and source records attributed to W F Coetzee.

18 recordsLinked to original sources
PubMed1984

Proteus mirabilis chromosome mobilization by plasmid D: a physical characterization.

Plasmid D, a hybrid of plasmids P-lac and R1 drd19, mediates polarized chromosome mobilization from one origin in Proteus mirabilis strain PM5006, while the parental plasmids neither individually nor combined mobilize this chromosome. To elucidate its acquired mobilizing ability plasmid D was characterized physically in relation to P-lac and R1 drd19. Restriction patterns of these plasmids were compared and it was shown that D consists of P-lac and only the r-determinant (r-det) of R1 drd19. A mechanism for the formation of plasmid D, via transduction of the r-det and subsequent transposon-like integration into P-lac, involving insertion sequence IS1, was suggested. Evidence for aberration in plasmid D DNA as a result of r-det integration into P-lac was attributed to IS1 elements which flank the r-det. Recombination regions of parental plasmid DNA were located on HindIII fragments alpha and beta of plasmid D and were subsequently inserted in vitro into IncP-1 plasmid RP4 that fails to mobilize the P. mirabilis chromosome. RP4::HindIII alpha plasmids did not mobilize the latter chromosome, but rendered the Proteus host lac+. RP4::HindIII beta plasmids pMC1 and pMC17, containing the fragment in opposite orientations, mobilized the P. mirabilis chromsome. For pMC17, mobilization was indistinguishable from that of plasmid D, i.e. having the same orientation and the same single origin. However, mobilization promoted by pMC1 was from two distinctly different origins, different from that of pMC17. This apparently deviates from known examples where inversion of homologous DNA inserted into plasmids leads to mobilization from the same origin but in reverse direction.

Chromosome Mapping↗
PubMed1983

Characteristics and classification of incC group plasmid-dependent phage C-1.

Incompatibility group C plasmid-specific bacteriophage C-1 has a buoyant density of 1.43 g/cm3, a sedimentation coefficient of 80-82S, and a molecular weight of 4 x 10(6). It contains approximately 33% nucleic acid, which has been identified as linear single-stranded RNA of molecular weight (1.3 +/- 0.1) x 10(6). These characteristics, in conjunction with particle morphology and resistance to chloroform and diethyl ether, suggest that phage C-1 belongs to the Leviviridae group of phages.

Bacteriophages↗
PubMed1982

Phages C-2 and J: IncC and IncJ plasmid-dependent phages, respectively.

Phages C-2 and J were isolated from sewage. Phage C-2 was filamentous and formed plaques on Salmonella typhimurium strains carrying various C plasmids. It also plated on Proteus mirabilis and Serratia marcescens strains carrying particular C plasmids, but failed to form plaques on lines of Escherichia coli K12 strains harbouring most of these plasmids, although in all cases, phage multiplication on the strains was demonstrated. No phage increase occurred in any strain which lacked a C plasmid or contained plasmids of other incompatibility groups. The phage was sensitive to chloroform and, unlike other filamentous bacterial viruses, adsorbed to shafts of conjugative pili. It had a disc-like structure at the end which attached to the pilus. Phage C-2 had a buoyant density of 1 . 30 g cm-3 and a single-stranded circular DNA genome of 3 . 0 MDal. Phage J had an hexagonal head with an inter-apical distance of 40 nm and a short noncontractile tail. It was resistant to chloroform and diethyl ether. The phage formed plaques or propagated on E. coli strains harbouring some IncC plasmids and all IncJ and IncD plasmids tested. The phage did not form plaques but propagated on P. mirabilis and Ser. marcescens strains carrying these plasmids. It did not plate or propagate on S. typhimurium strains harbouring the plasmids. The plaques were very hazy and variable in size. The phage attached sparsely, at a site which appeared to be located at the base of the tail, to sides of conjugative pili.

Adsorption↗
PubMed1982

Plasmid R394 is a cointegrate.

Plasmids R394a and R394b which cointegrate to form R394 are described. They have molecular masses of 102 +/- 4 and 11.0 +/- 0.4 MDal, belong to the T and N incompatibility groups and confer resistance to kanamycin and ampicillin, respectively. R394a is self transmissible and mobilizes R394b, which is non-self transmissible. These findings clarify anomalies in the behaviour of R394 and support suggestions based on the properties of variant phages derived from R394.

Conjugation, Genetic↗
PubMed1982

In vitro-constructed RP4-prime plasmids mediate orientated mobilization of the Proteus morganii chromosome.

RP4-prime plasmids containing inserts of Proteus morganii strain 2815 chromosomal DNA (0.5-13 megadaltons in size) were constructed in vitro. When introduced into the latter organism, the hybrid plasmids promoted transfer of chromosomal markers in an orientated manner, with recombinant frequencies from 10(-4) to 10(-6) per donor. Transconjugants expressed the tetracycline-resistant phenotype of the plasmids. Plasmid-guided trajectories overlapped and a circular map of chromosome markers was constructed. Correspondence between size of inserted chromosomal DNA in hybrid plasmids and numbers of markers transferred suggested that homology played a role in chromosome mobilization by these plasmids.

Chromosome Mapping↗
PubMed1981

Proteus mirabilis converting phage 5006Mpa has an oversized genome.

Proteus mirabilis phage 5006Mpa is a converting variant for ampicillin resistance of phage 5006M. We show here that the ampicillin resistance marker of transposon Tn1 is located on a 9.8% insertion with respect to the wild-type phage genome. This renders the 5006Mpa genome 5% oversized, albeit without loss of wild-type genetic material from the phage population.

Ampicillin↗
PubMed1980

Proteus mirabilis phages 5006M, 5006M HFT k and 5006M HFT ak: physical comparison of genome characteristics.

The genomes of proteus mirabilis phages 5006M, kanamycin resistance transducing variant 5006M HFT k and kanamycin-ampicillin resistance transducing variant 5006M HFT ak have been compared. Homo- and heteroduplex and partial denaturation mapping analyses were performed. The results confirm a sequential headful packaging mechanism, facilitate mapping of the ampicillin resistance marker, demonstrate a hairpin loop structure in both variants, reveal a common insertion site for 8 X 10(6) mol. wt. non-phage DNA in both variants and implicate a role for the non-inducible cryptic host strain prophage 5006M in the generatin cycle of the variant phages.

Ampicillin↗
PubMed1979

Pilus-specific, lipid-containing bacteriophages PR4 and PR772: comparison of physical characteristics of genomes.

The genomes of pilus-specific, lipid-containing phages PR4 and PR772 were studied electron microscopically. An identical mol. wt. of 10.9 x 10(6) was obtained. The genomes are unique (non-permuted) and have cohesive ends. From the similarities in size and denaturation maps of the genomes and failue to demonstrate non-homology in heteroduplexes, reported morphological ambiguities were clarified. The known serological difference between the phages could not be related to non-homology of their genomes. It is concluded that phages PR4 and PR772 are the same phage.

Coliphages↗
PubMed1979

Proteus mirabilis phage 5006M: a physical characterization.

This report deals with physical characterization of the generalized transducing Proteus mirabilis phage 5006M. The morphology of the phage is presented, the buoyant density was determined (1.491 g/ml) and the G + C content of the phage DNA was found to be 44%. The phage genome has a length of 14.8 micrometers and mol. wt. of 30.7 x 10(6). Denaturation mapping revealed non-random circular permutation of the phage DNA. The genome exhibits 3.6% terminal redundancy as shown by homoduplex analysis. The existence of concatemeric precursors of phage 5006M DNA is inferred and the results are interpreted in terms of a sequential headful packaging mechanism.

Bacteriophages↗
PubMed1979

Properties of R plasmid R772 and the corresponding pilus-specific phage PR772.

R plasmid R772 was isolated from a strain of Proteus mirabilis and is a self-transmissible P-1 incompatibility group plasmid having a molecular weight of about 27 x 10(6). It renders bacterial hosts resistant to kanamycin. Phage PR772 was isolated as a phage dependent on the presence of R772 in bacterial hosts. It is hexagonal-shaped with a diameter of 53 nm, has a thick inner membrane and no tail. Vaguely defined appendages are sometimes apparent at some vertices and the phage possesses double-stranded DNA. The DNA has a guanine plus cytosine molar content of 48%. The phage is sensitive to chloroform and has a buoyant density of 1.26 g cm(-3). These observations suggested that the inner membrane of the phage could contain lipid. Phage PR772 differs in morphology from the double-stranded DNA plasmid-specific phages PR4 and PRR1 which adsorb to tips and sides, respectively, of sex pili coded for by P-1 incompatibility group plasmids. Phage PR772 formed clear plaques which varied in diameter. Serologically, phages PR772 and PR4 are possibly related though very distantly, but the two phages have identical host ranges. Phage PR772 adsorbed by one of its apices to tips of sex pili coded for by plasmid R772 in Escherichia coli. It also formed plaques on Salmonella typhimurium Proteus morganii and Providence strains harbouring this plasmid as well as strains of E. coli carrying plasmids of incompatibility groups N or W. The phage produced areas of partial clearing on lawns of P. mirabilis PM5006 harbouring plasmid R772, the P-1 incompatibility group plasmid RP4, the W group plasmid RSa or the N group plasmid N3, and on lawns of Providence strain P29 carrying plasmid RP4.

Bacteriophages↗
PubMedDate not supplied

Molecular cloning of Proteus morganii phenylalanine deaminase gene in Escherichia coli.

The gene for phenylalanine deaminase (PAD) of Proteus morganii strain 2815 has been isolated on a 6.3-kb HindIII restriction fragment and cloned within RP4-prime plasmids, pYB2321 and pYB2322, in both orientations. Expression of the cloned gene in Escherichia coli strains was comparable to that in P. morganii 2815. The hybrid plasmids mobilized the 2815 chromosome with trajectories in reverse directions from an origin between ser-2 and ade-1, suggesting the map location of the PAD gene.

Amino Acid Oxidoreductases↗