Metabolismo de L-rhamnose em Pullularia pullulans

Orientador: Dr. Luiz Alberto Silva VeigaCoorientador: Dr. Luiz Ramon MarechalTese (Doutorado) -Universidade Federal do Paraná, Curso de Pós-Graduação em BioquímicaInclui referências: p. 66-75Resumo: A presença de L-rhamnose como única fonte de carbono no meio de cultura de Pullularia pullulans, induz a síntese de enzimas específicas que degradam L-rhamnose até piruvato e L-lactaldeído. Extratos de células de Pullularia pullulans crescidas em L-rhamnose, contém uma desidrogenase NAD+-dependente que catalisa a oxidação do desoxiaçúcar à sua correspondente y-lactona. Esses extratos contêm também uma lactonase que converte L-rhamnono-y-lactona a Lrhamnonato, uma desidratase que catalisa a transformação de Lrhamnonato a 2-ceto-3-desoxi-L-rhamnonato (KDR). Este último com posto (KDR) sofre uma clivagem a piruvato e L-lactaldeído em reação catalisada por uma aldolase. Os produtos das reações enzimáticas dessa via metabólica de degradação de L-rhamnose foram isolados e caracterizados. Não foram constatados intermediários fosforilados. Foram demonstradas a indução e também a repressão por catabólitos das enzimas da via em células de Pullularia pullulans, em repouso e em crescimento. A caracterização destas enzimas e seus respectivos produtos de catálise evidencia uma via oxidativa, ainda não descrita, para a degradação de L-rhamnose

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

Metabolismo de L-rhamnose em Pullularia pullulans

Orientador: Dr. Luiz Alberto Silva VeigaCoorientador: Dr. Luiz Ramon MarechalTese (Doutorado) -Universidade Federal do Paraná, Curso de Pós-Graduação em BioquímicaInclui referências: p. 66-75Resumo: A presença de L-rhamnose como única fonte de carbono no meio de cultura de Pullularia pullulans, induz a síntese de enzimas específicas que degradam L-rhamnose até piruvato e L-lactaldeído. Extratos de células de Pullularia pullulans crescidas em L-rhamnose, contém uma desidrogenase NAD+-dependente que catalisa a oxidação do desoxiaçúcar à sua correspondente y-lactona. Esses extratos contêm também uma lactonase que converte L-rhamnono-y-lactona a Lrhamnonato, uma desidratase que catalisa a transformação de Lrhamnonato a 2-ceto-3-desoxi-L-rhamnonato (KDR). Este último com posto (KDR) sofre uma clivagem a piruvato e L-lactaldeído em reação catalisada por uma aldolase. Os produtos das reações enzimáticas dessa via metabólica de degradação de L-rhamnose foram isolados e caracterizados. Não foram constatados intermediários fosforilados. Foram demonstradas a indução e também a repressão por catabólitos das enzimas da via em células de Pullularia pullulans, em repouso e em crescimento. A caracterização destas enzimas e seus respectivos produtos de catálise evidencia uma via oxidativa, ainda não descrita, para a degradação de L-rhamnose

Nitrogenase Switch-Off by Ammonium Ions in Azospirillum brasilense Requires the GlnB Nitrogen Signal-Transducing Protein

Nitrogenase activity in several diazotrophs is switched off by ammonium and reactivated after consumption. The signaling pathway to this system in Azospirillum brasilense is not understood. We show that ammonium-dependent switch-off through ADP-ribosylation of Fe protein was partial in a glnB mutant of A. brasilense but absent in a glnB glnZ double mutant. Triggering of inactivation by anaerobic conditions was not affected in either mutant. The results suggest that glnB is necessary for full ammonium-dependent nitrogenase switch-off in A. brasilense

Molecular mechanisms probably involved in plant colonization and plant growth promotion identified in the <i>H. seropedicae</i> SmR1 genome.

<p>Plant signals can modulate the expression of bacterial genes coding for adhesins, type IV <i>pili</i> and enzymes of lipopolysaccharide (LPS) synthesis, triggering bacterial attachment to root surfaces. The molecular communication involves bacterial protein secretion and phytohormones to stimulate plant growth and modulate plant defense response. In addition, modulation of plant ethylene levels by ACC deaminase may contribute to plant growth promotion. The success of the endophytic association depends on a compatible genetic background that leads to benefits for both organisms.</p

General features of the genome of <i>Herbaspirillum seropedicae</i> SmR1.

<p>General features of the genome of <i>Herbaspirillum seropedicae</i> SmR1.</p

Proposed pathways for aromatic compounds metabolism in <i>H. seropedicae</i> SmR1.

<p>Proposed pathways for aromatic compounds metabolism in <i>H. seropedicae</i> SmR1.</p

The genome of <i>Herbaspirillum seropedicae</i> SmR1.

<p>From inside to outside 1) G+C content; 2) GC skew; 3) genes color-coded according the COG functional categories; genes in the + strand and − strand are represented in the inside and outside circles respectively; 4) rRNAS operons; 5) putative horizontally transferred regions identified using IVOM: light red indicates low score and dark red indicates high score; 6) regions of <i>H. seropedicae</i> genome identical to castor bean (<i>Ricinus communis</i>) sequences (minimum of 200 bp in length and higher than 90% in identity).</p

The type III secretion system gene cluster of <i>H. seropedicae</i> SmR1 and other organisms.

<p>Genes of the same color in different organisms are homologous. Genes colored in black have no counterpart in the genomic regions shown.</p