Early colonization pattern of maize (Zea mays L. Poales, Poaceae) roots by Herbaspirillum seropedicae (Burkholderiales, Oxalobacteraceae)

The bacterium Herbaspirillum seropedicae is an endophytic diazotroph found in several plants, including economically important poaceous species. However, the mechanisms involved in the interaction between H. seropedicae and these plants are not completely characterized. We investigated the attachment of Herbaspirillum to maize roots and the invasion of the roots by this bacterium using H. seropedicae strain SMR1 transformed with the suicide plasmid pUTKandsRed, which carries a mini-Tn5 transposon containing the gene for the Discosoma red fluorescent protein (Dsred) constitutively expressed together with the kanamycin resistance gene. Integration of the mini-Tn5 into the bacterial chromosome yielded the mutant H. seropedicae strain RAM4 which was capable of expressing Dsred and could be observed on and inside fresh maize root samples. Confocal microscopy of maize roots inoculated with H. seropedicae three days after germination showed that H. seropedicae cell were attached to the root surface 30 min after inoculation, were visible in the internal tissues after twenty-four hours and in the endodermis, the central cylinder and xylem after three days

Genome of Herbaspirillum seropedicae Strain SmR1, a Specialized Diazotrophic Endophyte of Tropical Grasses

The molecular mechanisms of plant recognition, colonization, and nutrient exchange between diazotrophic endophytes and plants are scarcely known. Herbaspirillum seropedicae is an endophytic bacterium capable of colonizing intercellular spaces of grasses such as rice and sugar cane. The genome of H. seropedicae strain SmR1 was sequenced and annotated by The Paraná State Genome Programme—GENOPAR. The genome is composed of a circular chromosome of 5,513,887 bp and contains a total of 4,804 genes. The genome sequence revealed that H. seropedicae is a highly versatile microorganism with capacity to metabolize a wide range of carbon and nitrogen sources and with possession of four distinct terminal oxidases. The genome contains a multitude of protein secretion systems, including type I, type II, type III, type V, and type VI secretion systems, and type IV pili, suggesting a high potential to interact with host plants. H. seropedicae is able to synthesize indole acetic acid as reflected by the four IAA biosynthetic pathways present. A gene coding for ACC deaminase, which may be involved in modulating the associated plant ethylene-signaling pathway, is also present. Genes for hemagglutinins/hemolysins/adhesins were found and may play a role in plant cell surface adhesion. These features may endow H. seropedicae with the ability to establish an endophytic life-style in a large number of plant species

The complete genome sequence of Chromobacterium violaceum reveals remarkable and exploitable bacterial adaptability

Chromobacterium violaceum is one of millions of species of free-living microorganisms that populate the soil and water in the extant areas of tropical biodiversity around the world. Its complete genome sequence reveals (i) extensive alternative pathways for energy generation, (ii) ≈500 ORFs for transport-related proteins, (iii) complex and extensive systems for stress adaptation and motility, and (iv) wide-spread utilization of quorum sensing for control of inducible systems, all of which underpin the versatility and adaptability of the organism. The genome also contains extensive but incomplete arrays of ORFs coding for proteins associated with mammalian pathogenicity, possibly involved in the occasional but often fatal cases of human C. violaceum infection. There is, in addition, a series of previously unknown but important enzymes and secondary metabolites including paraquat-inducible proteins, drug and heavy-metal-resistance proteins, multiple chitinases, and proteins for the detoxification of xenobiotics that may have biotechnological applications

CD80 and CD86 polymorphisms in populations of various ancestries: 5 new CD80 promoter alleles

CD80 and CD86 are closely linked genes on chromosome 3 that code for glycoproteins of the immunoglobulin superfamily, expressed on the surface of antigen-presenting cells. These costimulatory molecules play essential roles for stimulation and inhibition of T cells through binding to CD28 and CTLA-4 receptors. In this study, CD80 promoter and CD86 exon 8 polymorphisms were analyzed to investigate the genetic diversity and microevolution of the 2 genes. We genotyped 1,124 individuals, including Brazilians of predominantly European, mixed African and European, and Japanese ancestry, 5 Amerindian populations, and an African sample. All variants were observed in Africans, which suggests their origin in Africa before the human migrations out of that continent. Five new CD80 promoter alleles were identified and confirmed by cloning and sequencing, and promoter 2 is most likely the ancestral allele. Nucleotide -79 is monomorphic in 4 Amerindian populations, where the presence of the -79 G allele is probably the result of gene flow from non-Amerindians. (C) 2012 American Society for Histocompatibility and Immunogenetics. Published by Elsevier Inc. All rights reserved.Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq)Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq)Institutos do MilenioInstitutos do MilenioPRONEXPRONEXFundacao Araucaria de Apoio ao Desenvolvimento Cientifico e Tecnologico do ParanaFundacao Araucaria de Apoio ao Desenvolvimento Cientifico e Tecnologico do ParanaCoordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES

The NtrY–NtrX two-component system is involved in controlling nitrate assimilation in Herbaspirillum seropedicae strain SmR1

Submitted by Luciane Willcox ([email protected]) on 2016-10-13T16:59:29Z No. of bitstreams: 1 The NtrY–NtrX two-component system.pdf: 919572 bytes, checksum: 2fa21e44abff448bcff5c6989d5353bd (MD5)Approved for entry into archive by Luciane Willcox ([email protected]) on 2016-10-13T17:17:07Z (GMT) No. of bitstreams: 1 The NtrY–NtrX two-component system.pdf: 919572 bytes, checksum: 2fa21e44abff448bcff5c6989d5353bd (MD5)Made available in DSpace on 2016-10-13T17:17:07Z (GMT). No. of bitstreams: 1 The NtrY–NtrX two-component system.pdf: 919572 bytes, checksum: 2fa21e44abff448bcff5c6989d5353bd (MD5) Previous issue date: 2016-09-16INCT-Fixação Biologica de Nitrogênio/CNPq/MCTI, CNPq, CAPES, Fundação Araucaria, Biotechnology and Biological Sciences Research Council (BB/L011468/1).Department of Biochemistry and Molecular Biology. Universidade Federal do Paraná. Curitiba, PR, Brasil.Department of Biochemistry and Molecular Biology. Universidade Federal do Paraná. Curitiba, PR, Brasil / Fundação Oswaldo Cruz. Instituto Carlos Chagas. Curitiba, PR, Brasil.Department of Biochemistry and Molecular Biology. Universidade Federal do Paraná. Curitiba, PR, Brasil.Department of Biochemistry and Molecular Biology. Universidade Federal do Paraná. Curitiba, PR, Brasil.Department of Biochemistry and Molecular Biology. Universidade Federal do Paraná. Curitiba, PR, Brasil.Department of Biochemistry and Molecular Biology. Universidade Federal do Paraná. Curitiba, PR, Brasil.Department of Life Sciences, Imperial College London, UKDepartment of Life Sciences, Imperial College London, UKDepartment of Life Sciences, Imperial College London, UKUniversidade Federal do Paraná. Department of Genetics. Curitiba, PR, Brasil.Department of Biochemistry and Molecular Biology. Universidade Federal do Paraná. Curitiba, PR, Brasil.Herbaspirillum seropedicae is a diazotrophic β-Proteobacterium found endophytically associated with gramineae (Poaceae or graminaceous plants) such as rice, sorghum and sugar cane. In this work we show that nitrate-dependent growth in this organism is regulated by the master nitrogen regulatory two-component system NtrB-NtrC, and by NtrY-NtrX, which functions to specifically regulate nitrate metabolism. NtrY is a histidine kinase sensor protein predicted to be associated with the membrane and NtrX is the response regulator partner. The ntrYntrX genes are widely distributed in Proteobacteria. In α-Proteobacteria they are frequently located downstream from ntrBC, whereas in β-Proteobacteria these genes are located downstream from genes encoding an RNA methyltransferase and a proline-rich protein with unknown function. The NtrX protein of α-Proteobacteria has an AAA+ domain, absent in those from β-Proteobacteria. An ntrY mutant of H. seropedicae showed the wild-type nitrogen fixation phenotype, but the nitrate-dependent growth was abolished. Gene fusion assays indicated that NtrY is involved in the expression of genes coding for the assimilatory nitrate reductase as well as the nitrate-responsive two-component system NarX-NarL (narK and narX promoters, respectively). The purified NtrX protein was capable of binding the narK and narX promoters, and the binding site at the narX promoter for the NtrX protein was determined by DNA footprinting. In silico analyses revealed similar sequences in other promoter regions of H. seropedicae that are related to nitrate assimilation, supporting the role of the NtrY-NtrX system in regulating nitrate metabolism in H. seropedicae