PCIS1, Encoded by a Pentatricopeptide Protein Co-expressed Gene, Is Required for Splicing of Three Mitochondrial nad Transcripts in Angiosperms.

Group II introns are large catalytic RNAs, which reside mainly within genes encoding respiratory complex I (CI) subunits in angiosperms' mitochondria. Genetic and biochemical analyses led to the identification of many nuclear-encoded factors that facilitate the splicing of the degenerated organellar introns in plants. Here, we describe the analysis of the pentatricopeptide repeat (PPR) co-expressed intron splicing-1 (PCIS1) factor, which was identified in silico by its co-expression pattern with many PPR proteins.

Functional flexibility of cyanobacterial light harvesting phycobilisomes enable acclimation to the complex light regime of mixing marine water columns.

The light environment in a mixing water column is arguably the most erratic condition under which photosynthesis functions. Shifts in light intensity, by an order of magnitude, can occur over the time scale of hours. In marine Synechococcus, light is harvested by massive, membrane attached, phycobilisome chromophore-protein complexes (PBS).

Group II Intron-Encoded Proteins (IEPs/Maturases) as Key Regulators of Nad1 Expression and Complex I Biogenesis in Land Plant Mitochondria.

Mitochondria are semi-autonomous organelles that produce much of the energy required for cellular metabolism. As descendants of a bacterial symbiont, most mitochondria harbor their own genetic system (mtDNA/mitogenome), with intrinsic machineries for transcription and protein translation. A notable feature of plant mitochondria involves the presence of introns (mostly group II-type) that reside in many organellar genes.

nMAT3 is an essential maturase splicing factor required for holo-complex I biogenesis and embryo development in Arabidopsis thaliana plants.

Group-II introns are self-splicing mobile genetic elements consisting of catalytic intron-RNA and its related intron-encoded splicing maturase protein cofactor. Group-II sequences are particularly plentiful within the mitochondria of land plants, where they reside within many critical gene loci. During evolution, the plant organellar introns have degenerated, such as they lack regions that are are required for splicing, and also lost their evolutionary related maturase proteins.