Circular proteins--no end in sight.
Circular proteins are a recently discovered phenomenon. They presumably evolved to confer advantages over ancestral linear proteins while maintaining the intrinsic biological functions of those proteins. In general, these advantages include a reduced sensitivity to proteolytic cleavage and enhanced stability. In one remarkable family of circular proteins, the cyclotides, the cyclic backbone is additionally braced by a knotted arrangement of disulfide bonds that confers additional stability and topological complexity upon the family. This article describes the discovery, structure, function and biosynthesis of the currently known circular proteins. The discovery of naturally occurring circular proteins in the past few years has been complemented by new chemical and biochemical methods to make synthetic circular proteins; these are also briefly described.
Trabi
Manuela
M
Institute for Molecular Bioscience, University of Queensland, QLD 4072, Brisbane, Australia.
Craik
David J
DJ
D000595:Amino Acid Sequence; D000818:Animals; D003500:Cyclization; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010456:Peptides, Cyclic / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism; D011487:Protein Conformation; D017510:Protein Folding; D017386:Sequence Homology, Amino Acid
D010456:Peptides, Cyclic