Tail Plate Research Articles

Structure and function of a novel coliphage-associated sialidase

A coliphage named 63D, isolated previously, associated sialidase as a component of phage particles. In order to localize the enzyme in phage particles, phages were partially destroyed by sonication, and the disrupted particles were size fractionated using a sucrose density gradient. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis, enzyme assay and electron micrography of the fractions revealed the enzyme to be composed of four identical subunits with a molecular mass of 90 kDa, and the subunits were cross-linked by disulfide bonds. Electron micrographic observation indicated that six enzyme molecules were localized in a phage tail plate as a hexagonal array.

Serotonergic Nervous System of Two Macrostomid Species: Recent or Ancient Divergence?

Serotonergic Nervous System of Two Macrostomid Species: Recent or Ancient Divergence?

The anatomy of the solute Girvanicystis batheri (?Chordata) from the Upper Ordovician of Scotland and a new species of Girvanicystis from the Upper Ordovician of South Wales

Detailed anatomical study of the solute Girvanicystis batheri from the Girvan starfish bed (Ashgill) has enabled the oral partition, hydropore, gonopore and the possible opening of a branchial slit to be identified. The distal part of the alimentary tract and the stomach were located in the posterior part of the head. Structures preserved as steinkernen are interpreted as a brain and left cranial nerve. The gross anatomy of G. batheri supports the hypothesis that it was a suspension feeder. Girvanicystis batheri is characterized by large plates on the dorsal surface of the head, 20 rings of the feeding arm and a nodular median plate on the ventral surface of the head. A new species of Girvanicystis, G. casteri, is described from the Sholeshook limestone (Ashgill) of South Wales. Girvanicystis casteri is distinguished from G. batheri in that the former has narrower head, a longer feeding arm and a spine on the median plate of the ventral surface of the head. Girvanicystis batheri has characters in common with the cornute Ceratocystis perneri, namely large plates of the skeleton of the head, right and left marginal flanges, opposite dorsal fore tail plates and alternate ventral fore tail plates, which suggest that G. batheri may also be a stem chordate.

Characterization of a phage infecting Propionibacterium freudenreichii

Bacteriophage 822 was isolated from a Swiss-type cheese. Out of 30 strains of Propionibacterium freudenieichii, only the strain TL 110 was sensitive to this phage. 822 morphology is very similar to those of phages infecting P acnes. It has an' isometric head, a non-contractile tail and a tail plate, so it belongs to the 81 group of 8radley's classifiCation. The 822 genome consists of a Iinear double-stranded DNA molecule 40 kb long with cohesive ends. .

EFFECT OF FREE-STREAM TURBULENCE ON SEPARATED-REATTACHING FLOWS FOR DIFFERENT ANGLES OF SEPARATION

Effects of a free-stream turbulence on a series of two-dimensional separation-reattaching flows (separation bubbles) were investigated experimentally in a low-speed wind tunnel. Models tested were two-dimensional triangular cylinders with a tail plate. Some important properties of the separation bubbles were measured with a split-film sensor driven by constant -temperature hot-wire anemometers. The effect of the turbulence on the reattachment length XR was found not to be uniform with respect to the separation angle. Large-scale vortices were formed by coalescence in the reattaching zone of the shear layer and were shed downstream with a non-dimensional frequency 0.65 ×(free-stream velocity) /XR, which was the same for all the combinations of the separation angle and the free-stream turbulence employed in this study. Geometry of the separated shear layer suggested that the large-scale vortices in the reattaching zone became flatter as XR increased.

Effects of free-stream turbulence on separated-reattaching flows for different angles of separation.

Effects of free-stream turbulence on a series of two-dimensional separated-reattaching flows ( separation bubbles ) were investigated experimentally in a low speed wind tunnel. Models tested were two-dimensional triangular cylinders with a tail plate. Some important properties of the separation bubbles were measured with a split-sensor driven by constant-temperature hot-wire anemometers. The effect of the turbulence on the reattachment length was found to be not uniform with respect to the separation angle. Large-scale vortices were formed by coalescence in the reattaching zone of the shear layer and were shed downstream with a non-dimensional frequency 0.65Uo/xR, which was the same for all combinations of the separation angle and the free-stream turbulence employed in this study. Geometry of the separated shear layer suggested that the large-scale vortices in the reattaching zone became flatter as xR increased.

Bacteriophage T4 baseplate components. III. Location and properties of the bacteriophage structural thymidylate synthetase.

Two T4D thymidylate synthetase (td) temperature-sensitive mutants have been isolated and characterized. Both mutants produce heat-labile phage particles. This observation supports the view that this viral-induced protein is a phage structural component. Further, antiserum to td has been shown to block a specific step in tail plate morphogenesis. The results indicated that the td protein is largely covered by the T4D tail plate gene 11 protein. Since the phageinduced dihydrofolate reductase (dfr) also is partially covered by the gene 11 protein, it appears that td was adjacent to the tail plate dfr. This location has been confirmed by constructing a T4D mutant which is dfrtstdts and showing that these two tail plate constituents interact and give altered physical properties to the phage particles produced. A structural relationship for the tail plate folate, dfr, and td has been reported.

Bacteriophage T4 baseplate components. I. Binding and location of the folic acid.

Two different proteins with high affinities for the pteridine ring of folic acid have been used to determine the location of this portion of the folate molecule in the tail plate of T4D and other T-even bacteriophage particles. The two proteins used were (i) antibody specific for folic acid and (ii) the folate-binding protein from bovine milk. Both proteins were examined for their effect on various intact and incomplete phage particles. Intact T2H was weakly inactivated by the antiserum but not by the milk protein. No other intact T-even phage, including T4D, was affected by these two proteins. When incomplete T4D particles were exposed in an in vitro morphogenesis system, it was found that neither of the two proteins affected either the addition of the long tail fibers to fiberless particles or the addition of tail cores to tail plates. On the other hand, these two proteins specifically blocked the addition of T4D gene 11 product to the bottom of T4D baseplates. After the addition of the gene 11 protein, these two reagents did not inhibit the further addition of the gene 12 protein to the baseplate. It can be concluded that the phage folic acid is a tightly bound baseplate constituent and that the pteridine portion of the folic acid is largely covered by the gene 11 protein.

Properties of Corynebacterium acnes bacteriophage and description of an interference phenomenon.

Nine virulent bacteriophages of the anaerobe Corynebacterium (Propionibacterium) acnes, the P-a series, are DNA phages, with long, curved nonretractile tails (130 nm) without tail plates or fibers. They have isometric heads (420 by 460 nm), and are placed in Bradley's group B-1. There is permanent plaque suppression at highest phage concentrations. After 100- to 1,000-fold dilution, plaques are evident. The latent period is 1 h and burst size 25. Cross-neutralization data of antisera for the nine phages are similar. There is an unexplained precipitous drop in plaque-forming units during the first 5 min of neutralization, after which the rate is linear for 2 h. They are sensitive to pH extremes but are partially protected even at pH 4 or 9 by storage at 4 C. They are resistant to ether and chloroform and are inactivated within 10 min at 70 C.

Morphology of the bacteriophages of lactic streptococci.

Electron microscope studies have been made of a number of phages of lactic streptococci, seven of which were phages of Streptococcus lactis C10. Two of the phages are thought to be identical; five have been classified by the method of Tikhonenko as belonging to group IV (phages with noncontractile tails) with type III tail plates; one belongs to group V (phages with tails possessing a contractile sheath). Both prolate polyhedral heads and isometric polyhedral heads are represented among the group IV phages. The phage drc3 of S. diacetilactis DRC3 has been shown to have similar structure to the group IV phages of S. lactis C10 with prolate polyhedral heads. The phages ml1, hp, c11, and z8 of the S. cremoris strains ML1, HP, C11, and Z8, respectively, were shown to belong to the group IV phages with type III tail plates by the method of Tikhonenko. All had octahedral heads and tended to be larger than most of the other phages studied.

Morphology of the Bacteriophages of Lactic Streptococci

Electron microscope studies have been made of a number of phages of lactic streptococci, seven of which were phages of Streptococcus lactis C10. Two of the phages are thought to be identical; five have been classified by the method of Tikhonenko as belonging to group IV (phages with noncontractile tails) with type III tail plates; one belongs to group V (phages with tails possessing a contractile sheath). Both prolate polyhedral heads and isometric polyhedral heads are represented among the group IV phages. The phage drc3 of S. diacetilactis DRC3 has been shown to have similar structure to the group IV phages of S. lactis C10 with prolate polyhedral heads. The phages ml1, hp, c11, and z8 of the S. cremoris strains ML1, HP, C11, and Z8, respectively, were shown to belong to the group IV phages with type III tail plates by the method of Tikhonenko. All had octahedral heads and tended to be larger than most of the other phages studied.

Bacteriophage-coded thymidylate synthetase. Evidence that the T4 enzyme is a capsid protein

It has previously been shown that T4 bacteriophage-coded dihydrofolate reductase is a capsid protein, specifically an element of the tail plate. This paper presents evidence that thymidylate synthetase is also a structural protein. Antiserum prepared against purified T4 thymidylate synthetase neutralizes T4 infectivity. Evidence is presented that structural thymidylate synthetase is the target of the antiphage component of the serum. The td gene in T4 codes for thymidylate synthetase. We have crossed the td gene from phage T6 into T4 and eliminated other T6 genetic material from the hybrid phage by extensive backcrossing. The hybrid phage, T4 td T6, is inactivated at 60 °C significantly more rapidly than the parent phage, T4D. Thus, the td gene is a determinant of a physical property of the virion, providing direct confirmation that thymidylate synthetase is a capsid protein. At present the role of the virion-bound enzyme is unknown.

An Adhesive Function for Modified Cilia in an Interstitial Turbellarian*

AbstractA modified cilium with an adhesive function has been found in an interstitial marine turbellarian Paratomella rubra (Acoela). This newly discovered cilium‐type is referred to as a haptocilium; it differs structurally from usual locomotory cilia only in the morphology of the tip. Inside the haptocilial tip is a lamellate, electron‐dense core, and visible outside the ciliary membrane of the tip is an amorphous secretion which is presumably the actual adhesive material by which the haptocilia are able to attach to surfaces. Haptocilia occupy a restricted area, a ventral tail plate, in Paratomella. They are motile and display a characteristic slow, irregular beat.

Function of T4D structural dihydrofolate reductase in bacteriophage infection.

Various properties of the bacteriophage structural dihydrofolate reductase (DFR) have been examined to determine its function during phage infection. It has been found that a binding site for reduced nicotinamide adenine dinucleotide phosphate (NADPH), most likely on the DFR present in the phage tail plate, is required for phage viability. Attachment of adenosine diphosphoribose, an analogue of NADPH, to this site prevents phage adsorption and injection. This adenosine diphosphoribose inhibition can be competitively reversed by the addition of NADPH or oxidized nicotinamide adenine dinucleotide phosphate. It is suggested that, during phage infection, the host bacterial cell might leak compounds functionally similar to the pyridine nucleotides. These compounds have been shown to nonenzymatically change the conformation of the phage tail plate DFR which is apparently necessary for successful injection.

Bacteriophage tail components. V. Complementation of T4D gene 28 - -infected bacterial extracts with pteroyl hexaglutamate.

Synthetic pteroyl hexaglutamate (9 x 10(-6) M) stimulated the formation of new T4D particles in vitro in extracts of Escherichia coli B infected with T4D gene 28(-). The stimulation was specific for this form of folic acid since neither pteroyl pentaglutamate nor pteroyl heptaglutamate stimulated phage formation. T4D formation in vitro in E. coli B extracts prepared after infection with 11 other phage mutants known to be involved in phage tail plate formation (5(-), 6(-), 7(-), 8(-), 10(-), 25(-), 26(-), 27(-), 29(-), 51(-), 53(-)) was not stimulated by the addition of pteroyl hexaglutamate. It can be concluded that the T4D gene 28 product is involved in the formation of the phage tail plate pteroyl hexaglutamate.

Bacteriophage of Haemophilus influenzae. 3. Morphology, DNA homology, and immunity properties of HPlcl, S2, and the defective bacteriophage from strain Rd.

The phages HP1c1 and S2 and a defective phage of Haemophilus influenzae have been compared. The morphology of the phages and the mol wt of their DNAs are similar, although the defective phage appears to have a different tail plate region. Electron microscope observation indicates that the defective phage does not attach to the cell surface, and its DNA appears to lack cohesive ends. The homology of the DNAs of the phages has been measured by hydridization. DNA from the defective phage shows little or no homology with the other phage DNAs. HP1c1 and S2 DNAs show a high level of homology. Each of these phages can form plaques on lawns of the lysogen of the other phage but at reduced plating efficiencies, suggesting that the two phages have related but not identical immunity systems.

Identity of genes coding for soluble and structural dihydrofolate reductases in bacteriophage T4.

By recombination between bacteriophage T4 wh2, a dihydrofolate reductaseless mutant, and T6, I have prepared T4 wh(T6), a T4 strain which codes for the T6-specific soluble dihydrofolate reductase. This strain has the heat sensitivity of T6, not T4, which provides direct evidence that the wh gene codes for both the soluble dihydrofolate reductase and the structural dihydrofolate reductase which is a constituent of T-even phage tail plates.

Bacteriophage tail components. 3. Use of synthetic pteroyl hexaglutamate for T4D tail plate assembly.

The assembly of T4D tail plates occurring during in vitro complementation reactions was found to be stimulated by pteroyl hexaglutamate. Neither the pteroyl pentaglutamate nor the pteroyl heptaglutamate substituted for the hexaglutamate. A small stimulation of the rate and amount of T4D tail plate assembly was observed in untreated extracts. A greater stimulation occurred when activated charcoal-treated bacterial extracts were used. Charcoal treatment inhibited complementation only when no preformed tail plates were present in the extracts, and the inhibition was reversed by the addition of 9 x 10(-6)m chemically synthesized pteroyl hexaglutamate. The stimulation is apparently due to a requirement for the pteroyl hexaglutamate for tail plate assembly.

Characterization of T-even bacteriophage substructures. II. Tail plates.

Tail plates obtained from T4D amber mutants were examined with respect to sedimentation behavior, subunit molecular weights, amino acid composition, isoelectric points, and morphology. Intact plates had an S(20,w) of 77S from pH 5 to 9. The only conformational change noted was that below pH 5 tail plates readily dimerized yielding vis-à-vis dimers with an S(20,w) of 124S. Dissociated plates consisted of three major proteins with molecular weights of 53 K +/- 5, 31 K +/- 3, and 17 K +/- 2 daltons. The amino acid analyses indicated that plates had a composition distinct from fibers and tubes and were relatively rich in tryptophan. Degradation studies with dimethyl sulfoxide (DMSO) indicated that tail plates had a unique biological structure. After treatment with DMSO, and to some extent without DMSO, or from lysates of defective mutants, tetrad structures were observed in the electron microscope. These structures had an amino acid content and relative amounts of types of subunits similar but not identical to intact plates. It was proposed that plates were composed of nine such tetrads giving rise to a structure with six- and threefold symmetry.

A C-terminal arginine residue necessary for bacteriophage T4D tail assembly

Arginine and certain arginine analogs have been found to inhibit reversibly Escherichia coli T4D bacteriophage tail assembly in in vitro complementation experiments. Active compounds all possessed unaltered carboxyl groups and a terminal guanidyl group. Using bacterial extracts prepared after infection with T4D amber mutants defective in different stages of assembly, it was found that the addition of the initial portion of the tail sheath to the substructure consisting of tail core plus tail plate was prevented by these compounds. In the presence of an inhibitor, tail intermediates accumulated. After the initial attachment of sheath monomers, further tail assembly (and head assembly) was resistant to these compounds. The relative ability of these various arginine-like compounds to inhibit tail assembly correlated with their ability to disrupt the tail structure of intact T-even phage particles. Carboxypeptidase B treatment of these bacterial extracts also prevented in vitro T4D tail assembly apparently by a direct enzymic attack on a C-terminal arginine residue of a protein of the phage tail. This inhibition by Carboxypeptidase B treatment was irreversible and the site of attack of the enzyme was found to be a component of the tail plate. The pattern of sensitivity of the various stages of tail assembly to the treatment by Carboxypeptidase B paralleled the sensitivity to inhibition by arginine-like compounds. These results support the conclusions (1) that the T4D tail plate contains a protein(s) with a C-terminal arginine residue(s) which during assembly forms polar bonds involving both its carboxyl and guanidyl groups with another phage component of the tail substructure; (2) added arginine prevents in vitro tail assembly by competing with the C-terminal arginine residues for the receptors; and (3) Carboxypeptidase B treatment prevents tail assembly by removing the C-terminal arginine residues.