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PubMedDate not supplied

[Physico-chemical properties of there phages of Pseudomonas syringae].

The properties of DNA for 9B, 123, 788/8 phages lysing phytopathogenic Pseudomonas syringae bacteria have been analysed with results presented. It was ascertained that their genomes consist of GC-type two-chain DNA molecules having molecular weight 14-15 mDa. It was shown that sedimentation coefficient for all three phage DNA is identical and equals 26S. GC-base percentage was calculated for the phage genomes. Its value, according to results of sedimentation analysis and melting temperature, was the same for 9B (51%, 57%) and 123 (51%, 57%) and differed for 788/8 (53%, 60%). The molecular weight of DNA phages calculated from the sum of fragments, obtained after genome splitting with restriction endonucleases is in agreement with the data of sedimentation analysis. The distribution of phage DNA fragments if electrophoregrams suggests the presence of numerous common restriction sites in the phages' genomes.

Bacteriophages↗
PubMed1998

The separation of alginate biosynthesis and acetylation in Pseudomonas syringae.

Seaweed alginate was acetylated by resting cells of Pseudomonas syringae subsp. phaseolicola ATCC 19304. Physiological studies on this strain and its UV-induced mutants showed no correlation between bacterial alginate biosynthesis and acetylation. Specific yields of alginate and degree of acetylation in these polymers varied with strain and culture medium. This was indirect evidence that alginate biosynthesis is separate from polysaccharide acetylation. It indicated that the enzyme system involved in alginate biosynthesis was not directly linked to alginate acetylation and explained why microbial acetylation of seaweed alginates was possible.

Acetylation↗
PubMed1974

Purification and characterization of syringacin 4-A, a bacteriocin from pseudomonas syringae 4-A.

Syringacin 4-A, a bacteriocin produced by Pseudomonas syrinagae 4-A, was obtained by induction with ultraviolet irradiation or mitomycin C. Approximately 1,000-fold purification of the bacteriocin was achieved by manganous chloride precipitation, differential centrifugation, and chromatography on hydroxyapatite columns. The purified syngacin was homogeneous on hydroxyapatite columns and sucrose density gradients; it also sedimented as a single entity in the analytical ultracentrifuge. The buoyant density of purified syringacin in cesium chloride was 1.294 g/ml. The sedimentation coefficient was calculated as 120S, and the diffusion coefficient was 6.49 x 10(-8) cm(2)/s. The molecular weight was calculated as 1.6 x 10(7) from physical data and 1.7 x 10(7) from biological data. The syringacin was composed of about 88.4% protein, 8.5% arabinose, 2.2% galacturonic acid, and 0.7% glucosamine. Amino acid analysis indicated a predominance of leucine (12.1%), aspartic acid (12.2%), and glutamic acid (12.7%). The ultraviolet spectrum showed a maximum absorbance peak at 276 nm. The syringacin was heat and alcohol sensitive, but resistant to trypsin, chymotrypsin, carboxypeptidase, Pronase, protease, lysozyme, steapsin, deoxyribonuclease, and ribonuclease. Maximum pH stability was between 5 and 8. Crude bacteriocin was stable at room temperature for at least a year, and purified material was stable for at least 3 months at 4 C.

Bacteriocins↗
PubMed1993

Structural studies of the enveloped dsRNA bacteriophage phi 6 of Pseudomonas syringae by Raman spectroscopy. I. The virion and its membrane envelope.

We report and interpret the first Raman spectrum of a double-stranded RNA virus containing a membrane envelope. Spectra of the native bacteriophage phi 6 and of its isolated host-attachment (spike) protein and phospholipid-free core assembly were collected from aqueous solutions over a wide range of temperature. Comparison of the vibrational spectra by digital difference methods permits the following structural conclusions regarding molecular constituents of the fully assembled virion. (1) The double-stranded RNA, phospholipid and protein components of the phage exhibit Raman amplitudes in accordance with their biochemically determined compositions in the native virion (10, 20 and 70%, respectively). (2) alpha-Helix and irregular conformations are the dominant secondary structures in proteins of both the viral membrane and nucleocapsid. This represents a departure from previously examined icosahedral phage and plant viruses, which are dominated by beta-sheet structures. (3) The phospholipids of the viral membrane are liquid crystalline throughout the determined range of virus thermostability (0 to 40 degrees C). (4) The P3 spike protein of phi 6, which is anchored to, but not sequestered within the viral membrane, is largely alpha-helical (approximately 35%) and highly thermolabile. Denaturation of P3 at temperatures above 30 degrees C leads to appreciable loss (approximately 20%) of alpha-helix in favor of beta-strand structure, and alters significantly the environments of many aromatic side-chains. (5) The secondary structures of integral membrane proteins of phi 6 are overwhelmingly alpha-helical (approximately 70 to 80%) and also thermolabile. In contrast to P3, which exhibits aspartate and glutamate carboxyls in the ionized form (CO2-), the integral membrane proteins exhibit only protonated carboxyl groups (COOH). Treatment of phi 6 with butylated hydroxytoluene (BHT), which has been shown to remove the P3 spike protein, does not significantly perturb phospholipids and associated integral proteins of the viral membrane or structural proteins and packaged double-stranded RNA of the nucleocapsid. However, P3 subunits, which are recovered after BHT treatment, exhibit radically altered secondary and tertiary structures, including the loss of most subunit alpha-helices. Among the P3 side-chains affected by BHT treatment, we note a general trend toward greater hydrophilicity and greater solvent exposure of the aromatic residues Trp and Tyr. On the other hand, the cysteine sulfhydryl groups of the BHT-isolated P3 monomer are not solvent exposed and function as strong hydrogen-bond donors in the protein core.(ABSTRACT TRUNCATED AT 400 WORDS)

Bacteriophage phi 6↗
PubMed1993

Structural studies of the enveloped dsRNA bacteriophage phi 6 of Pseudomonas syringae by Raman spectroscopy. II. Nucleocapsid structure and thermostability of the virion, nucleocapsid and polymerase complex.

Structures and thermostabilities of the double-stranded (ds) RNA bacteriophage phi 6 and of its isolated nucleocapsid-polymerase complex (nucleocapsid core) and dsRNA components have been investigated by Raman spectroscopy. The spectra show that proteins of the phi 6 virion are collectively deficient in beta-sheet secondary structure. In particular, the major protein (P8) of the outer spherical shell of the phi 6 nucleocapsid exhibits a secondary structure dominated largely by alpha-helix and irregular conformations. The absence of appreciable beta-structure in the P8 subunit suggests a tertiary conformation lacking the beta-barrel motif common to subunits of most other spherical viral capsids. In addition, the Raman spectra show that subunits of the dodecahedral nucleocapsid core are also predominantly alpha-helical. The results thus indicate a largely alpha-helical secondary structure for the major subunit (P1) of the phi 6 nucleocapsid core, as well as for the P8 subunit of the outer spherical shell. Using Raman difference spectroscopy, we demonstrate that proteins of the nucleocapsid core (P1, P2, P4 and P7) interact extensively with the packaged phi 6 RNA genome, and further, that conformational stability of the packaged RNA is reduced upon removal from the core. Also, we find that proteins of the phi 6 nucleocapsid are significantly more thermostable than proteins of the viral membrane envelope, which are reported in the accompanying paper (Li et al., 1993). The present results suggest that both the architectural principles and modes of protein-RNA interaction in the phi 6 virion differ fundamentally from those of icosahedral single-stranded RNA viruses. Both Raman and circular dichroism spectra indicate that the dsRNA genome of phi 6 is an A-form structure. The Raman marker bands signify the presence only of C3'-endo/anti nucleoside conformers. The Raman signature of dsRNA, revealed in the spectrum of the phi 6 genome, is discussed here as a model for assessing base-pairing and base-stacking interactions in other ribonucleoprotein assemblies.

Bacteriophage phi 6↗
PubMed1992

Genetic and functional analysis of the basic replicon of pPS10, a plasmid specific for Pseudomonas isolated from Pseudomonas syringae patovar savastanoi.

The sequence of a 1823 base-pair region containing the replication functions of pPS10, a narrow host-range plasmid isolated from a strain of Pseudomonas savastanoi, is reported. The origin of replication, oriV, or pPS10 is contained in a 535 base-pair fragment of this sequence that can replicate in the presence of trans-acting function(s) of the plasmid. oriV contains four iterons of 22 base-pairs that are preceded by G+C-rich and A+T-rich regions. A dnaA box located adjacent to the repeats of the origin is dispensable but required for efficient replication of pPS10; A and T are equivalent bases at the 5' end of the box. repA, the gene of a trans-acting replication protein of 26,700 Mr has been identified by genetic and functional analysis. repA is adjacent to the origin of replication and is preceded by the consensus sequences of a typical sigma 70 promoter of Escherichia coli. The RepA protein has been identified, using the minicell system of E. coli, as a polypeptide with an apparent molecular mass of 26,000. A minimal pPS10 replicon has been defined to a continuous 1267 base-pair region of pPS10 that includes the oriV and repA sequences.

Amino Acid Sequence↗