Chloroplast Structure of the Cryptophyceae

Abstract

Selective extraction and morphological evidence indicate that the phycobiliproteins in three Cryptophyceaen algae (Chroomonas, Rhodomonas, and Cryptomonas) are contained within intrathylakoidal spaces and are not on the stromal side of the lamellae as in the red and blue-green algae . Furthermore, no discrete phycobilisome-type aggregates have thus far been observed in the Cryptophyceae . Structurally, although not necessarily functionally, this is a radical difference . The width of the intrathylakoidal spaces can vary but is generally about 200-300 A . While the thylakoid membranes are usually closely aligned, granatype fusions do not occur. In Chroomonas these membranes evidence an extensive periodic display with a spacing on the order of 140-160 A . This periodicity is restricted to the membranes and has not been observed in the electron-opaque intrathylakoidal matrix .

Phycobiliprotein genes of the marine photosynthetic prokaryote Prochlorococcus: evidence for rapid evolution of genetic heterogeneity

“…S. Ting and others, unpublished). It remains to be explored whether the phycobiliproteins of Prochlorococcus are located within the intracytoplasmic lamellar space, as in cryptophytes (Gantt et al, 1971).…”

Cryptomonad biliproteins ? an evolutionary perspective

“…The chls are contained within integral thylakoid membrane protein-pigment complexes (Ingram and Hiller 1983;Lichtl6 et al 1987;Rhiel et al 1987), which appear to be distributed uniformly throughout the thylakoid membranes (Lichtl6 et al 1992). The phycobiliproteins are localized within the lumen of the thylakoid sacs (Dodge 1969;Wehrmeyer 1970;Gantt et al 1971 ;Rhiel et al 1985;Lichtl6 1979;Faust and Gantt 1986), and are wholly or in part associated with the lumenal surface of the thylakoid membrane (Spear-Bernstein and Miller 1987;Rhiel et al 1989;Ludwig and Gibbs 1989). A recent immunoelectron microscopy study of Cryptomonas rufescens suggests that whereas most of the phycoerythrin in this organism is within the thylakoid lumen, some of it is associated with the inner and outer surfaces of the thylakoid membranes (Lichtl6 et al 1992).…”

Evolution of a light-harvesting protein by addition of new subunits and rearrangement of conserved elements: Crystal structure of a cryptophyte phycoerythrin at 1.63-Å resolution

“…In any one species, there is only one type of PBP, either phycocyanin (PC) or phycoerythrin (PE); allophycocyanin is never present. The PC or PE is not organized into a phycobilisome but is instead located in the thylakoid lumen (16)(17)(18). Although the ␤ subunits of cryptophyte PBPs share a high degree of sequence identity with both the ␣ and ␤ subunits of cyanobacterial and red algal PBPs (19), the ␣ subunits are shorter, unrelated to other proteins in the sequence databases and carry a single, spectroscopically distinct bilin chromophore (20,21).…”