Large dsDNA chloroviruses encode diverse membrane transport proteins

•Chloroviruses are only known viruses that encode a complex suite of membrane transport proteins.•Chloroviruses encode K+ channels, aquaglyceroporin channels, K+ transporters, and Ca2+ transporting ATPases and possibly ligand-gated channels.•Chlorovirus encoded K+ channel proteins are the smallest known proteins to form a functional K+ channel.

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.