Large dsDNA chloroviruses encode diverse membrane transport proteins

Many large DNA viruses that infect certain isolates of chlorella-like green algae (chloroviruses) are unusual because they often encode a diverse set of membrane transport proteins, including functional K⁺ channels and aquaglyceroporins as well as K⁺ transporters and calcium transporting ATPases. Some chloroviruses also encode putative ligand-gated-like channel proteins. No one protein is present in all of the chloroviruses that have been sequenced, but the K⁺ channel is the most common as only two chloroviruses have been isolated that lack this complete protein. This review describes the properties of these membrane-transporting proteins and suggests possible physiological functions and evolutionary histories for some of them.