Coexistence of phycoerythrin and a chlorophyll a/b antenna in a marine prokaryote.

Abstract

Prochlorococcus marinus CCMP 1375, a ubiquitous and ecologically important marine prochlorophyte, was found to possess functional genes coding for the a and 1 subunits of a phycobiliprotein. The latter is similar to phycoerythrins (PE) from marine Synechococcus cyanobacteria and bind a phycourobilin-like pigment as the major chromophore. However, differences in the sequences of the ca and 13 chains compared with known PE subunits and the presence of a single bilin attachment site on the a subunit designate it as a novel PE type, which we propose naming PE-III. P. marinus is the sole prokaryotic organism known so far that contains chlorophylls a and b as well as phycobilins. These data strongly suggest that the common ancestor of prochlorophytes and the Synechococcus cyanobacteria contained phycobilins. Flow cytometric data from the tropical Pacific Ocean provide evidence that deep populations of Prochlorococcus possess low amounts of a PE-like pigment, which could serve either in light harvesting or nitrogen storage or both.

Complex microbiome underlying secondary and primary metabolism in the tunicate- Prochloron symbiosis

“…Similarly, all sequenced Prochlorococcus strains possess genes encoding an atypical phycoerythrin as the sole phycobiliprotein, which was hypothesized to be a photoreceptor (49,50). In Prochlorococcus cells, these genes were shown to be expressed at low levels, and the phycobiliprotein gene product was found in small but significant amounts (49,50). Further analyses are therefore needed to check whether P. didemni cpcBA operon is also expressed at low levels.…”

“…This includes a unique 7-aa deletion between positions 65 and 71 and a modified amino acid environment around the phycocyanobilin chromophore-binding cysteinyl residue (Cys-77). Similarly, all sequenced Prochlorococcus strains possess genes encoding an atypical phycoerythrin as the sole phycobiliprotein, which was hypothesized to be a photoreceptor (49,50). In Prochlorococcus cells, these genes were shown to be expressed at low levels, and the phycobiliprotein gene product was found in small but significant amounts (49,50).…”

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“…Indeed, it is not possible to immunodecorate subunits from a Synechocystis PS I preparation with the diatom LHC antibody. It could already be shown that Prochlorococcus marinus, a marine prochlorophyte phylogenetically affiliated with the cyanobacteria, does contain a chlorophyll a/b antenna besides genes encoding phycobiliproteins (Hess et al 1996). Furthermore, a group of genes encoding polypeptides related to the early light-inducible proteins (ELIP) and LHCs of higher plants, the one-helix high-light-inducible proteins [HLIP, for reviews see Green and Durnford (1996); Montané and Kloppstech (2000)] has been found in cyanobacteria (Funk and Vermaas 1999).…”

Species concepts and speciation factors in cyanobacteria, with connection to the problems of diversity and classification

“…Prochlorococcus, Prochlorothrix, and Prochloron are cyanobacteria that additionally produce chlorophyll b (the typical pigment of green algae and land plants) and lack phycobilisomes (Giddings et al 1980;Burger-Wiersma et al 1986;Miller et al 1988;Chisholm et al 1992;Hess et al 1996;Pinevich et al 1997;Kauff and Büdel 2011). On this basis and due to a psbA gene based phylogenetic analysis, they were considered strictly associated with the chloroplast of green algae and terrestrial plants (Morden and Golden 1989).…”