Rubredoxin A

Rubredoxin A (RubA) is a protein conserved across all studied oxygenic photoautotrophs.^[1]

Structure

As of March 2015 there was no crystal structure of RubA although a structure of the homologous protein from a cryptomonad was determined using NMR.^[2] Investigation of the gene however indicates that it differs from other known rubredoxins in being bound to the thylakoid membrane via a C-terminal transmembrane helix.^[1][3][4]

Function

An investigation of Guillardia theta noted that RubA had a similar distribution to Photosystem II (PSII) and immunological experiments indicated the presence of RubA in PSII complexes isolated from Spinacia oleracea.^[3] In Synechocystis sp. PCC 6803 it has been demonstrated that the insertion of an antibiotic cassette into the rubA gene results in a marked decrease in the amount of PSII present,^[1] while the same mutation within Chlamydomonas reinhardtii and in Arabidopsis thaliana results in a total absence of PSII.^[1]

Conversely, another study performed in Synechococcus sp. PCC 7002 indicated that mutation of the rubA gene interfered with iron-sulphur cluster assembly in Photosystem I (PSI), rather than affecting PSII.^[4][5]