Filamentous bacterial viruses

Marvin, D.A.; Wiseman, R.L.; Wachtel, Ellen

doi:10.1016/0022-2836(74)90336-2

Cited by 188 publications

(165 citation statements)

References 30 publications

Supporting

Mentioning

154

Contrasting

Unclassified

Order By: Relevance

“…There is no evidence for a hairpin fold in the helix, although minor disruptions along its length cannot be ruled out. Neighboring helices cross one another at an angle of 3-13°in a negative sense, rather than in the positive sense expected (17)(18)(19)(20) from theoretical (21) and experimental (22) (1,20). The path of the helical rod of electron density is shown in Fig.…”

Section: Pf1 Structurementioning

confidence: 99%

“…The structure of the Pfl virion at 7 A resolution was solved by consideration of.how regions of very strong intensity on the x-ray diffraction pattern define the distribution of electron density in the structure (1). This analysis showed that the 46-residue coat-protein subunits can be approximated by rods of electron density whose long axes are tilted slightly with respect to the axis of the virion, forming an overlapping interdigitating helical array.…”

mentioning

confidence: 99%

“…Two structural classes of filamentous bacterial viruses have been identified (1). Class 1, exemplified by the fd (= fl = M 13) species, has been extensively studied by biochemical and genetic techniques whereas class 2, exemplified by the Pfl species, gives higher resolution x-ray fiber diffraction data and has been intensively studied by structural techniques (reviewed in refs.…”

mentioning

confidence: 99%

See 2 more Smart Citations

Maximum-entropy calculation of the electron density at 4 A resolution of Pf1 filamentous bacteriophage.

Bryan¹,

Bansal²,

Folkhard³

et al. 1983

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

A 4 A electron-density map of Pf1 filamentous bacterial virus has been calculated from x-ray fiber diffraction data by using the maximum-entropy method. This method produces a map that is free of features due to noise in the data and enables incomplete isomorphous-derivative phase information to be supplemented by information about the nature of the solution. The map shows gently curved (banana-shaped) rods of density about 70 A long, oriented roughly parallel to the virion axis but slewing by about 1/6th turn while running from a radius of 28 A to one of 13 A. Within these rods, there is a helical periodicity with a pitch of 5 to 6 A. We interpret these rods to be the helical subunits of the virion. The position of strongly diffracted intensity on the x-ray fiber pattern shows that the basic helix of the virion is right handed and that neighboring nearly parallel protein helices cross one another in an unusual negative sense.Two structural classes of filamentous bacterial viruses have been identified (1). Class 1, exemplified by the fd (= fl = M 13) species, has been extensively studied by biochemical and genetic techniques whereas class 2, exemplified by the Pfl species, gives higher resolution x-ray fiber diffraction data and has been intensively studied by structural techniques (reviewed in refs. 2 and 3). Both classes of virion have a cylindrical protein coat of 60 A average outer diameter and 20 A average inner diameter encapsulating a single-stranded circular DNA molecule that stretches down the length of the central hole. The protein coat is essentially a helical array of several thousand identical protein units, although there are minor proteins at the ends of the virion that make up about 1% by weight of the coat.

show abstract

Section: Pf1 Structurementioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Maximum-entropy calculation of the electron density at 4 A resolution of Pf1 filamentous bacteriophage.

Bryan¹,

Bansal²,

Folkhard³

et al. 1983

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

show abstract

“…Class I includes the widely studied Ff (fd, f1, M13) group and class II includes the Pf1 and Pf3 strains. The architecture of the Pf1 capsid and the shape of the protein subunit were initially determined by direct interpretation of the distribution of strong diffracted intensity on low-resolution ®bre patterns, supplemented by molecular modelling, Fourier transform and electron-density calculations (Marvin et al, 1974;Nakashima et al, 1975;Marvin & Wachtel, 1975. Each 46-residue subunit measures about 1 Â 7 nm, with its gently curved -helix axis oriented at a small angle to the virion axis.…”

Section: Introductionmentioning

confidence: 99%

The molecular structure and structural transition of the α-helical capsid in filamentous bacteriophage Pf1

Welsh

Symmons

Marvin

2000

Acta Crystallogr D Biol Cryst

View full text Add to dashboard Cite

The major coat protein in the capsid of Pf1 ®lamentous bacteriophage (Inovirus) forms a helical assembly of about 7000 identical protein subunits, each of which contains 46 amino-acid residues and can be closely approximated by a single gently curved -helix. Since the viral DNA occupies the core of the tubular capsid and appears to make no signi®cant speci®c interactions with the capsid proteins, the capsid is a simple model system for the study of the static and dynamic properties of -helix assembly. The capsid undergoes a reversible temperature-induced structural transition at about 283 K between two slightly different helix forms. The two forms can coexist without an intermediate state, consistent with a ®rst-order structural phase transition. The molecular model of the higher temperature form was re®ned using improved X-ray ®bre diffraction data and new re®nement and validation methods. The re®nement indicates that the two forms are related by a change in the orientation of the capsid subunits within the virion, without a signi®cant change in local conformation of the subunits. On the higher temperature diffraction pattern there is a region of observed intensity that is not consistent with a simple helix of identical subunits; it is proposed that the structure involves groups of three subunits which each have a slightly different orientation within the group. The grouping of subunits suggests that a change in subunit libration frequency could be the basis of the Pf1 structural transition; calculations from the model are used to explore this idea.

show abstract

“…PM3 has Pseudomonas aeruginosa strains bearing the RP1 plasmid as hosts (2). Its length is about 700 nm (3,4), its mass-per-length is about 19,000 daltons/nm (4), its DNA contains about 6 kilobases (4), its principal protein subunit has molecular weight 4400 (B. Frangione, personal communication), and its x-ray diffraction patterns (W. Winter, personal communication) are more like those of Xf and Pf1 than those of fd and If (5,6). Spectral and chemical properties ofPf3 (unpublished data) show that its DNA structure is different from the DNA structures in Pf1, Xf, and fd (7,8).…”

mentioning

confidence: 99%

Conformational transitions in Pf3 and their implications for the structure and assembly of filamentous bacterial viruses.

Thomas¹,

Day²

1981

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

Laser Raman and circular dichroism spectra of filamentous bacteriophage Pf3 show that its coat protein is predominantly ca-helical, similar to the subunits ofbacteriophages Pf1 and fd. Unlike Pff and fd, however, the subunits of Pf3 are converted to P-sheet structures by raising the temperature, the transition temperature depending upon phage and NaCi concentrations. On cooling, the .8 structure reverts to an a structure the same as or similar to the native structure. On further heating it converts irreversibly to a second ai-helical form different from the original one. The spectra also show that aromatic amino acid residues of Ff3 undergo dramatic changes in molecular environment during the a --f3 transition. Similar transitions are observed to take place in the filamentous bacteriophage Xf.Pf3 virus is one ofseveral filamentous viruses that have a Gramnegative bacterium as host and a covalently closed singlestranded DNA molecule packed in a long (103 nm), slender (<10 nm diameter) sheath made of several thousand copies of a principal structure protein and a few copies of one or more other proteins located at the ends. The molecular biology and structures of those that have been studied most extensively, such as the closely related fd, M13, and fl, and the less related Ift, Pfl, and Xf, are described in a recent monograph (1). PM3 has Pseudomonas aeruginosa strains bearing the RP1 plasmid as hosts (2). Its length is about 700 nm (3, 4), its mass-per-length is about 19,000 daltons/nm (4), its DNA contains about 6 kilobases (4), its principal protein subunit has molecular weight 4400 (B. Frangione, personal communication), and its x-ray diffraction patterns (W. Winter, personal communication) are more like those of Xf and Pf1 than those of fd and If (5, 6). Spectral and chemical properties ofPf3 (unpublished data) show that its DNA structure is different from the DNA structures in Pf1, Xf, and fd (7,8).We report here that native Pf3 has a high content of a-helix and that dramatic transitions in protein structure occur when the temperature is raised, provided the virus concentration is high. We have also carried out some comparative measurements on Xf, Pf1, and fd, but most of the data obtained so far are for Pf3. The transitions have been observed through changes in laser Raman spectra, especially in the conformationally sensitive amide I and amide III Raman bands. These bands are widely used to distinguish a-helix, p-sheet, and irregular regions of the polypeptide backbone (9-12). A number of other bands are used to obtain structural information about protein side groups (13) and, for nucleic acids and nucleoproteins, about the bases and the sugar-phosphate backbone (14-16). Raman studies of Pf1 and fd have shown high a-helix content in the protein subunits (11, 12) as well as abnormal tyrosines (17,18) and the absence of sugar-phosphate backbone of the classic A type (11).Some aspects of the concentration dependence of the Pf3 structure transitions have been revealed by monitoring changes in circular...

show abstract

Filamentous bacterial viruses

Cited by 188 publications

References 30 publications

Maximum-entropy calculation of the electron density at 4 A resolution of Pf1 filamentous bacteriophage.

Maximum-entropy calculation of the electron density at 4 A resolution of Pf1 filamentous bacteriophage.

The molecular structure and structural transition of the α-helical capsid in filamentous bacteriophage Pf1

Conformational transitions in Pf3 and their implications for the structure and assembly of filamentous bacterial viruses.

Contact Info

Product

Resources

About