Sandbox Reserved 717: Difference between revisions

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Bacteriophage T4 belongs to the Myoviridae ~~Family~~ and to the Caudovirales ~~Order~~ because of ~~their~~ complex tail structure with a high number of proteins involved. It infects Escherichia coli bacteria.

Bacteriophage T4 belongs to the Myoviridae family and the Caudovirales order because of its complex tail structure with a high number of proteins involved. It infects Escherichia coli bacteria. It is consisting of three parts : a DNA-containing head, a doubles-tubed tail with a contractile outer tail-sheath and a baseplate with short and long tail fibers.

(image)

Each bacteriophage T4 baseplate is composed of at least 16 different gene products, also called gp. These gene products can be divided ~~into~~ groups: the 6 long and the 6 short tail fibers (on the schematic ~~rpresentation~~, they are not all shown). ~~OLIGOMERIQUE~~ They form a multiprotein machine which plays an important role at the first stage of a phage infection. It is essential for the host cell recognition, the attachment of the bacteriophage and the sheath contraction allowing viral DNA ejection.

Each bacteriophage T4 baseplate is composed of at least 16 different gene products, also called gp which are oligomeric proteins. These gene products can be divided in to groups: the six long and the six short tail fibers (on the schematic representation, they are not all shown). They form a multiprotein machine which plays an important role at the first stage of a phage infection. It is essential for the host cell recognition, the attachment of the bacteriophage and the sheath contraction allowing viral DNA ejection.

== '''Adsorption and penetration phases''' ==

First the viral particles recognize and bind reversibly to cell-surface lipopolysaccharide receptors thanks to six long tail fibers which are connected to the baseplate. ~~The~~ baseplate conformation changes: from a hexagon shape, it becomes a six-pointed star. This change can be the result of changing the interactions between ~~the~~ proteins.

First, the viral particles recognize and bind reversibly to the outer membrane protein C (OmpC) or the cell-surface lipopolysaccharide receptors thanks to six long tail fibers which are connected to the baseplate. After at least three long tail fibers have bound, the baseplate conformation changes: from a hexagon shape, it becomes a six-pointed star. This change can be the result of changing the interactions between proteins.

It has two consequences. The first one is the unfolding of the short tail fibers, which are under the baseplate. Thus, they are able to attach irreversibly to the host cell surface. The second one is the induction of the tail sheath’s contraction. Afterwards the tail tube is driving through the cell membrane. The activated lysozyme domain of gp5 degraded the peptidoglycan layer. To finish, the phage DNA single-stranded is injected into the bacterial cytoplasm through the tail tube.

== '''Role of ~~the protein 1OCY~~''' ==

== '''Role of gp12''' ==

During the first step of the lytic cycle, the short tail fibers gp12 is attached to the host cell.

A monomer of gp12 has a mass of 55.3 kDa. '''It is composed of two proteins: 1H6W and 1OCY'''. Each short tail is composed of three repetition of the monomer. Thanks to a three-dimensional cryoelectron microscopy, a reconstruction of the baseplate was determined to a resolution of 12 A.

Sandbox Reserved 717: Difference between revisions

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-Bacteriophage T4 belongs to the Myoviridae Family and to the Caudovirales Order because of their complex tail structure with a high number of proteins involved. It infects Escherichia coli bacteria.
+Bacteriophage T4 belongs to the Myoviridae family and the Caudovirales order because of its complex tail structure with a high number of proteins involved. It infects Escherichia coli bacteria. It is consisting of three parts : a DNA-containing head, a doubles-tubed tail with a contractile outer tail-sheath and a baseplate with short and long tail fibers.
 (image)
-Each bacteriophage T4 baseplate is composed of at least 16 different gene products, also called gp. These gene products can be divided into groups: the 6 long and the 6 short tail fibers (on the schematic rpresentation, they are not all shown). OLIGOMERIQUE They form a multiprotein machine which plays an important role at the first stage of a phage infection. It is essential for the host cell recognition, the attachment of the bacteriophage and the sheath contraction allowing viral DNA ejection.
+Each bacteriophage T4 baseplate is composed of at least 16 different gene products, also called gp which are oligomeric proteins. These gene products can be divided in to groups: the six long and the six short tail fibers (on the schematic representation, they are not all shown). They form a multiprotein machine which plays an important role at the first stage of a phage infection. It is essential for the host cell recognition, the attachment of the bacteriophage and the sheath contraction allowing viral DNA ejection.
 == '''Adsorption and penetration phases''' ==
-First the viral particles recognize and bind reversibly to cell-surface lipopolysaccharide receptors thanks to six long tail fibers which are connected to the baseplate. The baseplate conformation changes: from a hexagon shape, it becomes a six-pointed star. This change can be the result of changing the interactions between the proteins.
+First, the viral particles recognize and bind reversibly to the outer membrane protein C (OmpC) or the cell-surface lipopolysaccharide receptors thanks to six long tail fibers which are connected to the baseplate. After at least three long tail fibers have bound, the baseplate conformation changes: from a hexagon shape, it becomes a six-pointed star. This change can be the result of changing the interactions between proteins.
-It has two consequences. The first one is the unfolding of the short tail fibers, which are under the baseplate.  Thus, they are able to attach irreversibly to the host cell surface. The second one is the induction of the tail sheath’s contraction. Afterwards the tail tube is driving through the cell membrane. The activated lysozyme domain of gp5 degraded the peptidoglycan layer. To finish, the phage DNA single-stranded is injected into the bacterial cytoplasm through the tail tube.
+It has two consequences. The first one is the unfolding of the short tail fibers, which are under the baseplate. Thus, they are able to attach irreversibly to the host cell surface. The second one is the induction of the tail sheath’s contraction. Afterwards the tail tube is driving through the cell membrane. The activated lysozyme domain of gp5 degraded the peptidoglycan layer. To finish, the phage DNA single-stranded is injected into the bacterial cytoplasm through the tail tube.
-== '''Role of the protein 1OCY''' ==
+== '''Role of gp12''' ==
 During the first step of the lytic cycle, the short tail fibers gp12 is attached to the host cell.
 A monomer of gp12 has a mass of 55.3 kDa. '''It is composed of two proteins: 1H6W and 1OCY'''. Each short tail is composed of three repetition of the monomer. Thanks to a three-dimensional cryoelectron microscopy, a reconstruction of the baseplate was determined to a resolution of 12 A.