RESUMO
Photosystem II (PSII) mutants are useful experimental tools to trap potential intermediates involved in the assembly of the oxygen-evolving PSII complex. Here, we focus on the subunit composition of the RC47 assembly complex that accumulates in a psbC null mutant of the cyanobacterium Synechocystis sp. PCC 6803 unable to make the CP43 apopolypeptide. By using native gel electrophoresis, we showed that RC47 is heterogeneous and mainly found as a monomer of 220 kDa. RC47 complexes co-purify with small Cab-like proteins (ScpC and/or ScpD) and with Psb28 and its homologue Psb28-2. Analysis of isolated His-tagged RC47 indicated the presence of D1, D2, the CP47 apopolypeptide, plus nine of the 13 low-molecular-mass (LMM) subunits found in the PSII holoenzyme, including PsbL, PsbM and PsbT, which lie at the interface between the two momomers in the dimeric holoenzyme. Not detected were the LMM subunits (PsbK, PsbZ, Psb30 and PsbJ) located in the vicinity of CP43 in the holoenzyme. The photochemical activity of isolated RC47-His complexes, including the rate of reduction of P680(+), was similar to that of PSII complexes lacking the Mn(4)CaO(5) cluster. The implications of our results for the assembly and repair of PSII in vivo are discussed.
Assuntos
Proteínas de Bactérias/metabolismo , Genes Bacterianos , Complexos de Proteínas Captadores de Luz/metabolismo , Complexo de Proteína do Fotossistema II/metabolismo , Synechocystis/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/isolamento & purificação , Transporte de Elétrons , Eletroforese em Gel de Poliacrilamida , Deleção de Genes , Holoenzimas/genética , Holoenzimas/metabolismo , Complexos de Proteínas Captadores de Luz/genética , Complexos de Proteínas Captadores de Luz/isolamento & purificação , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Peso Molecular , Oxirredução , Oxigênio/metabolismo , Processos Fotoquímicos , Complexo de Proteína do Fotossistema II/genética , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Ligação Proteica , Mapeamento de Interação de Proteínas , Estabilidade Proteica , Transporte Proteico , Synechocystis/genética , Tilacoides/metabolismoRESUMO
The transport medium Multi-Microbe Media (M4) was evaluated prospectively by culture and direct enzyme-linked immunosorbent assay (ELISA) for detection of herpes simplex virus from 473 specimens. In addition, 377 specimens in Bartels Viral Transport Medium were evaluated. By using culture as a "gold standard," the ELISA sensitivity was approximately 85%, while the specificities exceeded 96% for both media.