Deciphering the genome repertoire of Pseudomonas sp. M1 toward β-Myrcene biotransformation

Pseudomonas sp. M1 is able to mineralize several unusual substrates of natural and xenobiotic origin, contributing to its competence to thrive in different ecological niches. In this work, the genome of M1 strain was resequenced by Illumina MiSeq to refine the quality of a published draft by resolving the majority of repeat-rich regions. In silico genome analysis led to the prediction of metabolic pathways involved in biotransformation of several unusual substrates (e.g., plant-derived volatiles), providing clues on the genomic complement required for such biodegrading/biotransformation functionalities. Pseudomonas sp. M1 exhibits a particular sensory and biotransformation/biocatalysis potential toward β-myrcene, a terpene vastly used in industries worldwide. Therefore, the genomic responsiveness of M1 strain toward β-myrcene was investigated, using an RNA sequencing approach. M1 cells challenged with β-myrcene(compared with cells grown in lactate) undergo an extensive alteration of the transcriptome expression profile, including 1,873 genes evidencing at least 1.5-fold of altered expression (627 upregulated and 1,246 downregulated), toward β-myrcene-imposed molecular adaptation and cellular specialization. A thorough data analysis identified a novel 28-kb genomic island, whose expression was strongly stimulated in β-myrcene-supplemented medium, that is essential for β-myrcene catabolism. This island includes β-myrcene-induced genes whose products are putatively involved in 1) substrate sensing, 2) gene expression regulation, and 3) β-myrcene oxidation and bioconversion of β-myrcene derivatives into central metabolism intermediates. In general, this locus does not show high homology with sequences available in databases and seems to have evolved through the assembly of several functional blocks acquired from different bacteria, probably, at different evolutionary stages.Acknowledgments This work was supported by FEDER through POFC— COMPETE and by national funds from Foundation for Science and Technology (Portugal) through the projects PEst-C/BIA/UI4050/2011, PTDC/EBB-BIO/104980/2008 and PTDC/BIA-MIC/113733/09, and through a PhD grant (grant number SFRH/BD/76894/2011) to P.S.-C.info:eu-repo/semantics/publishedVersio

Alcaloïdes des Annonacées, 68 : alcaloïdes des feuilles de Guatteria ouregou

Des feuilles de #Guatteria ouregou$, Annonacée guyanaise, ont été isolés 22 alcaloïdes aporphiniques, dont 6 nouveaux, et appartiennent à des types structuraux originaux. Les résultats mettent en évidence une grande différence dans la composition en alcaloïdes entre les différents organes de la plante, dont la signification chimiotaxonomique est ici discutée. (Résumé d'auteur

Production of taxoids with biological activity by plants and callus culture from selected Taxus genotypes

Twenty seven different yew trees belonging to various genotypes and hybrids have been screened for their capacity to produce significant amounts of taxoids provided with biological activity in the tubulin test. From the three best genotypes selected, Taxus x media "Sargentii" proved to be able to produce viable calluses from excised roots placed in vitro. Taxoid composition at various times of the in vitro culture was determined and the carcinostatic efficiency of the extracts was established using the KB cell cytotoxicity test. In leaves and calluses, respectively, 0.069 and 0.032% paclitaxel (taxol) contents were found. These contents were significantly higher than those previously reported for other genotypes

Abnormal vacuoles distinct from lysosomes in a mouse model of mucopolysaccharidosis type IIIB

International audienceProgressive accumulation of large intracellular vesicles is a hallmark of cell pathology in lysosomal storage diseases. Accumulating vesicles are commonly identified as crippled lysosomes engorged with incompletely digested materials resulting form the genetic defect. Our study of cortical neurons of the mouse model of mucopolysaccharidosis IIIB (Sanfilippo syndrome type B), a lysosomal storage disease with predominant neurological manifestations, showed efficient endocytosis, macro-autophagy and trafficking between endoplasmic reticulum and Golgi. Vesicles accumulating in these cells have a unique membrane phenotype associating the lysosomal marker LAMP1 with markers of the early secretory pathway, suggesting that they do not result from amplification of the pre-existing lysosomal compartment but rather arise from disease-related vesicular trafficking defects producing abnormal dead-end organelles related to but distinct from lysosomes. The generation and accumulation of abnormal vesicles unable to resolve could be a major cause of progressive intracellular storage in mucopolysaccharidosis IIIB neurons