Caudovirales

The order Caudovirales (Latin cauda, tail) comprises three families of viruses that use bacteria and archaea as hosts. The members of the Caudovirales thus belong to the group of bacteriophages. The subdivision of the families is mainly due to the morphology of the seated on the capsid tail piece: Myoviridae (long contractile tail ), Siphoviridae (long non- contractile tail ) and Podoviridae (short non- contractile tail ).

Features

All Caudovirales have a single molecule of double stranded DNA as a genome with a size of 18-500 kbp. Besides the usual nucleotides of the genetic code, the Caudovirales have also modified, eg glycosylated bases ( with attached additional sugar residues ) or 5- hydroxymethylcytosine in place of cytosine. The DNA is in a 45 to 170 nm in diameter, large icosahedral capsid made ​​of 72 capsomers usually; the tail can be up to 230 nm long.

The genome encodes 27 to more than 600 genes whose arrangement varies greatly. The genome can be broken by single gaps and possess covalently bound terminal proteins. Bacterium in the Caudovirales can integrate into the nucleoid ( prophage ) or remain in the cell as a linear or circular plasmid. The number of isolated genomes is relatively high because the Caudovirales subject to constant genetic exchange between viral and bacterial genome as well as the horizontal exchange as plasmid between bacteria. This results in a variety of so-called " mosaic types."

Dissemination

The Caudovirales are phylogenetically very old viruses with large population variations and global distribution. It is estimated that about virions of Caudovirales are in our biosphere, aneinandergelgt a distance of 2x lightyears correspond. The Caudovirales make up the major part of the Virioplanktons in the seas and waters.

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