Prochloron didemni P1-Palau
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ABSTRACT:
PROVIDER: PRJNA13452 | ENA |
REPOSITORIES: ENA
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Project description:Patellamides are macrocyclic peptides with potent biological effects and are a subset of the cyanobactins. Cyanobactins are natural products that are produced by a series of enzymatic transformations and a common modification is the addition of a prenyl group. Puzzlingly, the pathway for patellamides in Prochloron didemni contains a gene, patF, with homology to prenylases, but patellamides are not themselves prenylated. The structure of the protein PatF was cloned, expressed, purified and determined. Prenylase activity could not be demonstrated for the protein, and examination of the structure revealed changes in side-chain identity at the active site. It is suggested that these changes have inactivated the protein. Attempts to mutate these residues led to unfolded protein.
| S-EPMC3668578 | biostudies-literature
Project description:The prochlorophytes, oxygenic photosynthetic prokaryotes containing chlorophylls a and b, have been put forward as descended from the organisms that gave rise to chloroplasts of green plants and algae by endosymbiosis, although this has always been controversial. To assess the phylogenetic position of the prochlorophyte Prochloron didemni, we have cloned and sequenced its atpBE genes. Phylogenetic inference under a range of models gives moderate to strong support for a cyanobacterial grouping rather than a chloroplast one. Possible systematic errors in this and previous analyses of prochlorophyte sequences are discussed.
| S-EPMC48738 | biostudies-other
Project description:Prochloron didemni P3-Solomon Metagenomic Assembly
| PRJNA82335 | ENA
Project description:Prochloron didemni P2-Fiji Metagenomic Assembly
| PRJNA82333 | ENA
Project description:Prochloron didemni P4-Papua_New_Guinea Metagenomic Assembly
| PRJNA82337 | ENA
Project description:Prochlorophytes are a class of cyanobacteria that do not use phycobiliproteins as light-harvesting systems, but contain chlorophyll (Chl) a/b-binding Pcb proteins. Recently it was shown that Pcb proteins form an 18-subunit light-harvesting antenna ring around the photosystem I (PSI) trimeric reaction center complex of the prochlorophyte Prochlorococcus marinus SS120. Here we have investigated whether the symbiotic prochlorophyte Prochloron didemni also contains the same supermolecular complex. Using cells isolated directly from its ascidian host, we found no evidence for the presence of the Pcb-PSI supercomplex. Instead we have identified and characterized a supercomplex composed of photosystem II (PSII) and Pcb proteins. We show that 10-Pcb subunits associate with the PSII dimeric reaction center core to form a giant complex having an estimated Mr of 1,500 kDa with dimensions of 210 x 290 A. Five-Pcb subunits flank each long side of the dimer and assuming each binds 13 Chl molecules, increase the antenna size of PSII by approximately 200%. Fluorescence emission studies indicate that energy transfer occurs efficiently from the Pcb antenna. Modeling using the x-ray structure of cyanobacterial PSII suggests that energy transfer to the PSII reaction center is via the Chls bound to the CP47 and CP43 proteins.
| S-EPMC166436 | biostudies-literature
Project description:Prochloron spp. are obligate cyanobacterial symbionts of many didemnid family ascidians. It has been proposed that the cyclic peptides of the patellamide class found in didemnid extracts are synthesized by Prochloron spp., but studies in which host and symbiont cells are separated and chemically analyzed to identify the biosynthetic source have yielded inconclusive results. As part of the Prochloron didemni sequencing project, we identified patellamide biosynthetic genes and confirmed their function by heterologous expression of the whole pathway in Escherichia coli. The primary sequence of patellamides A and C is encoded on a single ORF that resembles a precursor peptide. We propose that this prepatellamide is heterocyclized to form thiazole and oxazoline rings, and the peptide is cleaved to yield the two cyclic patellamides, A and C. This work represents the full sequencing and functional expression of a marine natural-product pathway from an obligate symbiont. In addition, a related cluster was identified in Trichodesmium erythraeum IMS101, an important bloom-forming cyanobacterium.
| S-EPMC1091749 | biostudies-literature