RESUMO
In the model cyanobacterium Synechocystis sp. PCC 6803, the terminal enzyme of chlorophyll biosynthesis, chlorophyll synthase (ChlG), forms a complex with high light-inducible proteins, the photosystem II assembly factor Ycf39 and the YidC/Alb3/OxaI membrane insertase, co-ordinating chlorophyll delivery with cotranslational insertion of nascent photosystem polypeptides into the membrane. To gain insight into the ubiquity of this assembly complex in higher photosynthetic organisms, we produced functional foreign chlorophyll synthases in a cyanobacterial host. Synthesis of algal and plant chlorophyll synthases allowed deletion of the otherwise essential native cyanobacterial gene. Analysis of purified protein complexes shows that the interaction with YidC is maintained for both eukaryotic enzymes, indicating that a ChlG-YidC/Alb3 complex may be evolutionarily conserved in algae and plants.
Assuntos
Proteínas de Arabidopsis/metabolismo , Proteínas de Bactérias/metabolismo , Carbono-Oxigênio Ligases/metabolismo , Complexo de Proteína do Fotossistema II/metabolismo , Synechocystis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Bactérias/genética , Carbono-Oxigênio Ligases/classificação , Carbono-Oxigênio Ligases/genética , Luz , Fotossíntese/efeitos da radiação , Complexo de Proteína do Fotossistema II/genética , Filogenia , Ligação Proteica/efeitos da radiação , Synechocystis/genética , Tilacoides/metabolismo , Tilacoides/efeitos da radiaçãoRESUMO
Ten glycopeptide-resistant Enterococcus faecium isolates from separate patients in Laikon General Hospital, Athens were studied. Eight isolates had the VanA phenotype and represented variants of three strains based on SmaI macrorestriction banding patterns. Their VanA elements were compared with the prototype element, Tn1546, by an overlapping PCR method. Three related isolates contained resistance elements indistinguishable from Tn1546 (designated Greek type I). The other five isolates all contained identical elements that differed from Tn1546 by the presence of IS1251 between vanS and vanH, by a point mutation (G --> T) at nucleotide position 8234 within vanX and by a partial loss of transposition gene orf1 (designated Greek type II). Two distinct strains of E. faecium with the VanB phenotype were obtained. HhaI digestion of an amplified fragment of the vanB gene indicated that both strains contained the vanB2 allele, and further PCR assays confirmed that the vanB2 gene cluster was located within a Tn5382-like element.