This is the C-terminal domain of Prochloron sp. PatG, which process the precursor peptide to yield the cyclic Patellamide. The C-terminal domain of PatG is 56% structurally homologous to the C-terminal domain of PatA [1].

1: The structure of the cyanobactin domain of unknown function from PatG in the patellamide gene cluster. Mann G, Koehnke J, Bent AF, Graham R, Houssen W, Jaspars M, Schwarz-Linek U, Naismith JH; Acta Crystallogr F Struct Biol Commun. 2014;70:1597-1603. PMID:25484206