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structural assembly of the tailed bacteriophage ϕ29

by:Kenwei      2019-09-11
The mature virus grain of the tail-type phages ϕ 29 is a kind ~ 33 MDa complexes containing more than 450 subunits of 7 structural proteins assembled into protruding heads and short non-
Shrink the tail.
Here, we report.
Atomic structure of φ 29 pre-
Genome packaging head (prohead)
Mature viral grains and genomesemptied virion.
Structural comparison indicates local rotation or oscillation of the head
Tail connectors at the time of DNA packaging and release.
Termination of DNA packaging through stress-
The position and conformational changes associated with the connector. The funnel-
The bottom-end collar connects the expansion narrow end of the connector with a 180-Å long, 24-
A chain β-barrel narrow stem tube that experiences a conformational change during genome release.
The attachment forms an interlocking assembly that connects the tail around the collar.
Later in the infection, the membrane active long loop at the end of the tail knob exits and forms a cone-
The shape tip of the large drain spiral barrel prepared for membrane penetration.
Bacterial virus in the tail (bacteriophages)
It is a giant polymer complex assembled from hundreds of sub-units.
The coat head of tail bacteria is a stable long or long protein shell, which can protect the virus genome and resist harsh environmental conditions.
Machinery responsible for a particular host --
Cell identification and infection
The tail is attached to the head of a special vertex of the shell, in which the five-Poly shell is replaced by a protein component called a connector or inlet.
The head and tail have different symmetry, and it is recommended to assemble them into complex virus machines in a fixed relationship.
Bacteriophage 29, a type with short non-
Shrink the tail and have a protein code of 20 ~ 19kb dsDNA genome.
Both ends of the genome and end protein gene products 3 (gp3).
Infected G-29
Positive cells were obtained by injecting the genome-gp3 complex into the host
Using short non-cellular pulp
Shrink the tail and empty the virus particles from the genome on the surface of the cell (Fig. ).
Translation of later peptide genes including the main shell protein gp8 and head fiber protein gp8.
5, scaffold protein gp7 and connector protein gp10 start empty pro-capsid shell (prohead)(Fig. ).
DsDNA packaging machinery is assembled on prohead by connecting the short prohead RNA encoded by the virus (pRNA)
And atp gp16 around the connector.
The motor can package the genome dsDNA-gp3 complex into an empty prohead through the channel of the connector. Low-
The resolution structure data shows that there are only 5 pRNAs on each prohead (Fig. ).
However, the number of copies of pRNAs is a controversial topic.
Early crystal structure studies of scaffold protein gp7 show that two gp7 molecules form arrows-like homodimer.
The position of scaffold protein in the head is not yet clear.
PRNA and gp16 atp enzymes are separated from the head when triggering an unclear headfull signal.
Then, the tail proteins gp11, gp9, gp12 and gp13 are attached in turn to form mature virus particles (Fig. ). Previous low-
Resolution Electron Microscope (EM)
Structural studies have shown that the main shell protein of the mature Vivo 29 head is assembled into the first 20 bodies of the Vivo = Vivo 3, Vivo = 5 (Fig. ). Low-
The resolution structure of the main shell protein gp8 shows that it uses an additional C-
Terminal immunoglobulin-like (Ig-like)domain.
However, the atomic structure of the 29 islands is still missing.
There are 55 fibers protruding from the head (Fig. ).
Each of the head fibers is the same trimer of gp8.
5, by a pseudo
Hexagonal base and protruding stem with unique Threestranded helix-turn-
Spiral super-spiral structure.
Pseudo structural details
The hexagonal alkali and its interaction with gp8 are being determined.
The crystal structure of the connector indicates that it is a 12-polymer of gp10, with the center channel range ranging from about 37 °f at the narrow end to 60 °f at the wide end.
The narrow end of the connector is raised with the lower collar protein gp11 and has different conformations connected with the tail.
After the bulge is the tail shaft or tail tube, which is also part of the lower collar protein gp11 (Fig. ).
Gp11 is considered to play an important role in maintaining the end of the genome.
However, gp11 has no sequence similarity with other tube proteins, so little is known about the molecular structure of the tail tube and its interaction with the connector.
Each attachment (tail spike)
Is the same family of gp12 *, responsible for the host-
Cell recognition.
12 accessories are suspended on the raised outer surface through 12 arms (Fig. ).
Crystal structure of C-
The terminal receptor recognition domain of Gp12 * has been reported before, while N-
The end arm is not determined and it is not clear the attachment of the attachment to the tail.
The distal end of the tail shaft is connected to the tail knob, most of which are assembled by the tail protein gp9.
Tail enzyme
Just like the protein gp13 is considered part of the tail knob.
Gp9 contains a drain hole-forming loop (L loop)
For violation of host-
Cell membrane at the time of infection (Fig. ).
The atomic details of gp9 assembly after genome injection are still missing.
Here we are.
Electron microscope (cryo-EM)
Research on the structure of φ 29 prohead, maturity and genome
Empty virus particles nearby
Atomic resolution up to 3. 2u2009Å.
An all-atomic model of three complex virus particles was established.
Complete maturity and genome
Each of the empty viral particle models includes 235 major cocotenin gp8 and 165 minor cotenin gp8.
5. 12 copies of joint protein gp10 and tail protein gp11, 12*36 copies of tail accessory protein, and 6 copies of tail knob protein gp9.
The Prohead model includes 5 copies of pRNA, 110 copies of the scaffold protein gp7, and the number of copies of the same shell and junction protein as the mature protein or genome
Empty particles
It is worth noting that by comparing the structure, we found that the connector was pushed out of the shell about 13 km/h during the maturity of the head, which indicates the pressure-
The mechanism of dependence on the termination of DNA packaging.
In addition, the determined tail tube structure shows a unique β-
Barrel structure.
The tail attachment forms an interlocking assembly around the tail bump, which may help the host-cell receptors.
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