Cloning and sequencing of the genes encoding the alpha and beta subunits of C-phycocyanin from the cyanobacterium Agmenellum quadruplicatum.

Abstract

Synthetic oligonucleotide probes were used to identify a cloned DNA fragment from the cyanobacterium Agmenellum quadruplicatum that contains the genes for the a and 13 subunits of C-phycocyanin. The coding region for the a- The derived amino acid sequences for both C-phycocyanin subunits were compared with other known C-phycocyanin sequences for homology. Homologies between the A. quadruplicatum a subunit and a subunits from other species were ==70%, as were homologies between the A. quadruplicatum 13 subunit and other 13 subunits. Homologies between the various a and 13 subunits were 21%-27%. Codon usage for both the C-phycocyanin a-and -subunit genes shows asymmetries for many amino acids that correspond closely to those seen in highly expressed Escherichia coli genes.Phycobiliproteins are protein-chromophore conjugates found in cyanobacteria (blue-green algae) as well as in rhodophytes (red algae) and cryptomonads. They are accessory photosynthetic pigments and may comprise as much as 40%-60%o of the soluble protein in these cells (1-3). Thus, phycobiliproteins are major metabolic products of these organisms. These proteins can be divided into three classes based on their spectral properties: phycoerythrins, phycocyanins, and allophycocyanins. The basic structural unit of the proteins contains one a chain and one p chain. The a polypeptide is covalently linked to one bilin derivative; the 8 polypeptide is covalently linked to two bilin derivatives. In vivo, phycobiliproteins exist in higher aggregation states with the (a)6 form generally believed to be the functionally important aggregate (3-6).The role of phycobiliproteins is to trap light energy in the 500-to 650-nm wavelength range and to transfer it to chlorophyll a of photosystem II. In vivo, this transfer of energy occurs with an efficiency approaching 100% (7). Measurements of energy transfer in both intact algal cells and isolated phycobilisomes (8)(9)(10)(11) have shown that light energy is normally first absorbed by phycoerythrin, then transferred to phycocyanin, then to allophycocyanin, and finally to chlorophyll a. It has further been established that the transfer of energy within a phycobiliprotein is from the / chain to the a chain (12)(13)(14).

Genes encoding core components of the phycobilisome in the cyanobacterium Calothrix sp. strain PCC 7601: occurrence of a multigene family

“…In all cyanobacteria examined so far, the two subunits (a and 1B) of the major phycobiliproteins (AP, PC, and PE) are encoded by adjacent and cotranscribed genes (3,6,11,15,25,28,29,34). The genes specifying the linker polypeptides associated with either PC or AP are also found downstream from those coding for the PB with which they are associated.…”

Mutations that affect structure and assembly of light-harvesting proteins in the cyanobacterium Synechocystis sp. strain 6701

“…Definition of the genetic lesions in these mutants may best be approached by DNA sequence analysis now that biliprotein genes from other cyanobacteria have been cloned and sequenced (6,7,20).…”

The complete amino acid sequence of R‐phycocyanin‐I α and β subunits from the red alga Porphyridium cruentum

“…, Pilot and Fox (1984) Walsh et al (1980) Lau et al (1987a), Kalla et al (1988) Wilson et al (1991) Anderson and Grossman (1990) Apt and Grossman (1993b) Minami et al (1985) Offner and Pilot and Fox (1984), Glazer (1987) Freidenreich et al (1978), Williams and Glazer (1978), Glazer (1987) Lau et al (1987b), Kalla et al (1988) Wilson et al (1991 Anderson and Grossman (1990) Sidler et al (1990) Apt and Grossman (1993b) Minami et al (1985) Offner and Troxler (1983) Bryant et al (1985) Sidler et al (1981, Riimbeli et al (1987) Houmard et al (1986, Klotz et al (1986) Su et al (1992 Some cyanobacteria are found under several names depending on the publications and the data banks. For clarity, only the most common used strain designations (from the point of view of the authors) have been used for the table above.…”