RESUMEN
Mitochondria are important organelles that provide energy for the life of cells. Group II introns are usually found in the mitochondrial genes of land plants. Correct splicing of group II introns is critical to mitochondrial gene expression, mitochondrial biological function, and plant growth and development. Ancestral group II introns are self-splicing ribozymes that can catalyze their own removal from pre-RNAs, while group II introns in land plant mitochondria went through degenerations in RNA structures, and thus they lost the ability to self-splice. Instead, splicing of these introns in the mitochondria of land plants is promoted by nuclear- and mitochondrial-encoded proteins. Many proteins involved in mitochondrial group II intron splicing have been characterized in land plants to date. Here, we present a summary of research progress on mitochondrial group II intron splicing in land plants, with a major focus on protein splicing factors and their probable functions on the splicing of mitochondrial group II introns.
Asunto(s)
Embryophyta , Empalme del ARN , Intrones/genética , Empalme del ARN/genética , Mitocondrias/genética , Mitocondrias/metabolismo , ARN/metabolismo , Embryophyta/genética , Factores de Empalme de ARN/genéticaRESUMEN
Pentatricopeptide repeat (PPR) proteins form a large protein family in land plants, with hundreds of different members in angiosperms. In the last decade, a number of studies have shown that PPR proteins are sequence-specific RNA-binding proteins involved in multiple aspects of plant organellar RNA processing, and perform numerous functions in plants throughout their life cycle. Recently, computational and structural studies have provided new insights into the working mechanisms of PPR proteins in RNA recognition and cytidine deamination. In this review, we summarized the research progress on the functions of PPR proteins in plant growth and development, with a particular focus on their effects on cytoplasmic male sterility, stress responses, and seed development. We also documented the molecular mechanisms of PPR proteins in mediating RNA processing in plant mitochondria and chloroplasts.
Asunto(s)
Regulación de la Expresión Génica de las Plantas , Desarrollo de la Planta , Proteínas de Plantas/metabolismo , Plantas/metabolismo , Proteínas de Plantas/genéticaRESUMEN
In order to improve manganese-SOD stability, three mutations were constructed via site-directed mutagenesis, and the root mean square fluctuation (RMSF) and root mean square deviation (RMSD) were used as stability assessment indexes. The amino acids of V140, E155 and E215 from wild-type mouse Mn-SOD was replaced to L140, W155 and W215, and a recombinant plasmid containing DNA segment coding wild-type and mutant Mn-SOD protein was transformed into Escherichia coli BL21 for expression. The highest enzyme activity of the mutations-MnSOD was 2050â¯U/mg. In addition, the recombinant protein, TM-MnSODV140L, E155W, E215W exhibited higher working temperature and improved stability compared with the wild-type Mn-SOD. Furthermore, CD spectrum analysis of the improved mutants and wild-type enzyme showed that there was no significant change in their secondary structures. This study not only expands the scope of the application of enzymes, but also helps us understand the relationship between protein structure and function.
Asunto(s)
Sustitución de Aminoácidos , Simulación de Dinámica Molecular , Ingeniería de Proteínas , Superóxido Dismutasa/química , Animales , Estabilidad de Enzimas , Concentración de Iones de Hidrógeno , Ratones , Mutagénesis Sitio-Dirigida , Conformación Proteica , Proteínas Recombinantes , Análisis Espectral , Relación Estructura-Actividad , Superóxido Dismutasa/genética , Superóxido Dismutasa/aislamiento & purificación , TermodinámicaRESUMEN
Chemotherapy targeting anti-angiogenesis in tumors may have insufficient efficacy, but little is known about the underlying mechanisms. Here, we showed that the Ca(2+)-permeable channel, TrpC5, is highly expressed in human breast cancer after long-term chemotherapy drug-treatment. It mediates downstream hypoxia-inducible factor 1α accumulation in the nucleus, and then activates the transcription of vascular endothelial growth factor which promotes tumor angiogenesis, leading to a poor chemotherapeutic outcome. We verified this mechanism at both the cellular and xenograft levels. Moreover, in samples from patients, high TrpC5 expression was correlated with enhanced tumor vasculature after chemotherapy. Taken together, our research demonstrated the essential role of TrpC5 in tumor angiogenesis when facing the challenge of chemotherapy and presents a new potential target for overcoming the high vasculature of human breast cancer after chemotherapy.
Asunto(s)
Neoplasias de la Mama/metabolismo , Subunidad alfa del Factor 1 Inducible por Hipoxia/metabolismo , Canales Catiónicos TRPC/metabolismo , Factor A de Crecimiento Endotelial Vascular/metabolismo , Animales , Antibióticos Antineoplásicos/farmacología , Neoplasias de la Mama/tratamiento farmacológico , Línea Celular Tumoral , Doxorrubicina/farmacología , Femenino , Humanos , Ratones Desnudos , Neovascularización Patológica/metabolismo , ARN Interferente Pequeño/administración & dosificación , Canales Catiónicos TRPC/genética , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
Through protein-protein BLAST of homologous sequences in different species in NCBI database and preliminary simulating molecular docking and molecular dynamics by computer software discovery studio 3.1, three amino acids R25K26K27 of natural human parathyroid hormone (1-34) with Q25E26L27 were mutated and the biological activity of the mutant peptide was evaluated. Result showed that: root mean superposition deviation RMSD value between PTH (1-34)-(RKK-QEL) and PTH (1-34) peptide main chain was 2.509 3, indicating that the differences between the two main chain structural conformation was relatively small; the interaction energy between PTH (1-34)-(RKK-QEL) and its receptor protein PTH1R had been enhanced by 7.5% compared to nature PTH (1-34), from -554.083 kcal x mol(-1) to -599.253 kcal x mol(-1); the number of hydrogen bonds was increased from 32 to 38; PTH (1-34)-(RKK-QEL) can significantly stimulate the RANKL gene expression (P < 0.01) while inhibiting the OPG gene expression (P < 0.01) in UAMS-32P cells; in the co-culture system of UAMS-32P cells and mouse primary femur bone marrow cells, PTH (1-34)-(RKK-QEL) stimulated the formation of osteoclasts (P < 0.01) and had a higher biological activity than PTH (1-34) standard reagents.