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Dive into the research topics where Beatriz Galán is active.

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Featured researches published by Beatriz Galán.


Journal of Bacteriology | 2004

The Homogentisate Pathway: a Central Catabolic Pathway Involved in the Degradation of l-Phenylalanine, l-Tyrosine, and 3-Hydroxyphenylacetate in Pseudomonas putida

Elsa Arias-Barrau; Elías R. Olivera; José M. Luengo; Cristina Fernández; Beatriz Galán; José Luis García; Eduardo Díaz; Baltasar Miñambres

Pseudomonas putida metabolizes Phe and Tyr through a peripheral pathway involving hydroxylation of Phe to Tyr (PhhAB), conversion of Tyr into 4-hydroxyphenylpyruvate (TyrB), and formation of homogentisate (Hpd) as the central intermediate. Homogentisate is then catabolized by a central catabolic pathway that involves three enzymes, homogentisate dioxygenase (HmgA), fumarylacetoacetate hydrolase (HmgB), and maleylacetoacetate isomerase (HmgC), finally yielding fumarate and acetoacetate. Whereas the phh, tyr, and hpd genes are not linked in the P. putida genome, the hmgABC genes appear to form a single transcriptional unit. Gel retardation assays and lacZ translational fusion experiments have shown that hmgR encodes a specific repressor that controls the inducible expression of the divergently transcribed hmgABC catabolic genes, and homogentisate is the inducer molecule. Footprinting analysis revealed that HmgR protects a region in the Phmg promoter that spans a 17-bp palindromic motif and an external direct repetition from position -16 to position 29 with respect to the transcription start site. The HmgR protein is thus the first IclR-type regulator that acts as a repressor of an aromatic catabolic pathway. We engineered a broad-host-range mobilizable catabolic cassette harboring the hmgABC, hpd, and tyrB genes that allows heterologous bacteria to use Tyr as a unique carbon and energy source. Remarkably, we show here that the catabolism of 3-hydroxyphenylacetate in P. putida U funnels also into the homogentisate central pathway, revealing that the hmg cluster is a key catabolic trait for biodegradation of a small number of aromatic compounds.


Journal of Bacteriology | 2000

Functional Analysis of the Small Component of the 4-Hydroxyphenylacetate 3-Monooxygenase of Escherichia coli W: a Prototype of a New Flavin:NAD(P)H Reductase Subfamily

Beatriz Galán; Eduardo Díaz; María Auxiliadora Prieto; José Luis García

Escherichia coli W uses the aromatic compound 4-hydroxyphenylacetate (4-HPA) as a sole source of carbon and energy for growth. The monooxygenase which converts 4-HPA into 3,4-dihydroxyphenylacetate, the first intermediate of the pathway, consists of two components, HpaB (58.7 kDa) and HpaC (18.6 kDa), encoded by the hpaB and hpaC genes, respectively, that form a single transcription unit. Overproduction of the small HpaC component in E. coli K-12 cells has facilitated the purification of the protein, which was revealed to be a homodimer that catalyzes the reduction of free flavins by NADH in preference to NADPH. Subsequently, the reduced flavins diffuse to the large HpaB component or to other electron acceptors such as cytochrome c and ferric ion. Amino acid sequence comparisons revealed that the HpaC reductase could be considered the prototype of a new subfamily of flavin:NAD(P)H reductases. The construction of a fusion protein between the large HpaB oxygenase component and the choline-binding domain of the major autolysin of Streptococcus pneumoniae allowed us to develop a rapid method to efficiently purify this highly unstable enzyme as a chimeric CH-HpaB protein, which exhibited a 4-HPA hydroxylating activity only when it was supplemented with the HpaC reductase. These results suggest the 4-HPA 3-monooxygenase of E. coli W as a representative member of a novel two-component flavin-diffusible monooxygenase (TC-FDM) family. Relevant features on the evolution and structure-function relationships of these TC-FDM proteins are discussed.


Molecular Microbiology | 2011

Nucleoid‐associated PhaF phasin drives intracellular location and segregation of polyhydroxyalkanoate granules in Pseudomonas putida KT2442

Beatriz Galán; Nina Dinjaski; B. Maestro; L. I. de Eugenio; Isabel F. Escapa; J. Sanz; JoséL. García; María Auxiliadora Prieto

The PhaF is a nucleoid‐associated like protein of Pseudomonas putida KT2442 involved in the polyhydroxyalkanoate (PHA) metabolism. Its primary structure shows two modular domains; the N‐terminal PHA granule‐binding domain (phasin domain) and the C‐terminal half containing AAKP‐like tandem repeats characteristic of the histone H1 family. Although the PhaF binding to PHA granules and its role as transcriptional regulator have been previously demonstrated, the cell physiology meaning of these properties remains unknown. This work demonstrates that PhaF plays a crucial role in granule localization within the cell. TEM and flow cytometry studies of cells producing granules at early growth stage demonstrated that PhaF directs the PHA granules to the centre of the cells, forming a characteristic needle array. Our studies demonstrated the existence of two markedly different cell populations in the strain lacking PhaF protein, i.e. cells with and without PHA. Complementation studies definitively demonstrated a key role of PhaF in granule segregation during the cell division ensuring the equal distribution of granules between daughter cells. In vitro studies showed that PhaF binds DNA through its C‐terminal domain in a non‐specific manner. All these findings suggested a main role of PhaF in PHA apparatus through interactions with the segregating chromosome.


Environmental Microbiology | 2010

The turnover of medium-chain-length polyhydroxyalkanoates in Pseudomonas putida KT2442 and the fundamental role of PhaZ depolymerase for the metabolic balance

Laura I. de Eugenio; Isabel F. Escapa; Valle Morales; Nina Dinjaski; Beatriz Galán; José Luis García; María Auxiliadora Prieto

Polyhydroxyalkanoates (PHAs) are biodegradable polymers produced by a wide range of bacteria, including Pseudomonads. These polymers are accumulated in the cytoplasm as carbon and energy storage materials when culture conditions are unbalanced and hence, they have been classically considered to act as sinks for carbon and reducing equivalents when nutrients are limited. Bacteria facing carbon excess and nutrient limitation store the extra carbon as PHAs through the PHA polymerase (PhaC). Thereafter, under starvation conditions, PHA depolymerase (PhaZ) degrades PHA and releases R-hydroxyalkanoic acids, which can be used as carbon and energy sources. To study the influence of a deficient PHA metabolism in the growth of Pseudomonas putida KT2442 we have constructed two mutant strains defective in PHA polymerase (phaC1)- and PHA depolymerase (phaZ)-coding genes respectively. By using these mutants we have demonstrated that PHAs play a fundamental role in balancing the stored carbon/biomass/number of cells as function of carbon availability, suggesting that PHA metabolism allows P. putida to adapt the carbon flux of hydroxyacyl-CoAs to cellular demand. Furthermore, we have established that the coordination of PHA synthesis and mobilization pathways configures a functional PHA turnover cycle in P. putida KT2442. Finally, a new strain able to secrete enantiomerically pure R-hydroxyalkanoic acids to the culture medium during cell growth has been engineering by redirecting the PHA cycle to biopolymer hydrolysis.


Microbial Biotechnology | 2012

Catabolism and biotechnological applications of cholesterol degrading bacteria

José Luis García; I. Uhía; Beatriz Galán

Cholesterol is a steroid commonly found in nature with a great relevance in biology, medicine and chemistry, playing an essential role as a structural component of animal cell membranes. The ubiquity of cholesterol in the environment has made it a reference biomarker for environmental pollution analysis and a common carbon source for different microorganisms, some of them being important pathogens such as Mycobacterium tuberculosis. This work revises the accumulated biochemical and genetic knowledge on the bacterial pathways that degrade or transform this molecule, given that the characterization of cholesterol metabolism would contribute not only to understand its role in tuberculosis but also to develop new biotechnological processes that use this and other related molecules as starting or target materials.


Environmental Microbiology | 2011

Initial step in the catabolism of cholesterol by Mycobacterium smegmatis mc2155

I. Uhía; Beatriz Galán; Valle Morales; José Luis García

The first step in the catabolism of cholesterol, i.e. the transformation of cholesterol into cholestenone, has been investigated in Mycobacterium smegmatis. In silico analysis identified the MSMEG_1604 gene encoding a putative protein similar to the ChoD cholesterol oxidase of M. tuberculosis H37Rv (Rv3409c) and the MSMEG_5228 gene coding for a protein similar to the NAD(P)-dependent cholesterol dehydrogenase/isomerase of Nocardia sp. The expression of the MSMEG_5228 gene was inducible by cholesterol whereas the expression of MSMEG_1604 gene was constitutive. When both genes were expressed in Escherichia coli only the MSMEG_5228 protein was active on cholesterol. The function of ChoD-like MSMEG_1604 protein remains to be elucidated, but it does not appear to play a critical role in the mineralization of cholesterol as a MSMEG_1604(-) mutant was not affected in the production of cholestenone. However, a MSMEG_5228(-) mutant showed a drastic reduction in the synthesis of cholestenone. The finding that this mutant was still able to grow in cholesterol, allowed us to demonstrate that the cholesterol-inducible MSMEG_5233 gene encodes an additional cholesterol dehydrogenase/isomerase similar to the AcmA dehydrogenase of Sterolibacterium denitrificans. The observation that the double MSMEG_5228-5233(-) mutant was able to grow in cholesterol suggests that in addition to these enzymes other dehydrogenase/isomerases can also catalyse the first reaction of the cholesterol degradation pathway in M. smegmatis, which is not the limiting step of the process.


Environmental Microbiology Reports | 2012

Cholesterol metabolism in Mycobacterium smegmatis

I. Uhía; Beatriz Galán; Sharon L. Kendall; Neil G. Stoker; José Luis García

The metabolism of cholesterol in Mycobacterium smegmatis mc(2) 155 has been investigated by using a microarray approach. The transcriptome of M. smegmatis growing in cholesterol was compared with that of cells growing in glycerol as the sole carbon and energy sources during the middle exponential phase. Microarray analyses revealed that only 89 genes were upregulated at least threefold during growth on cholesterol compared with growth on glycerol. The upregulated genes are scattered throughout the 7 Mb M. smegmatis genome and likely reflect a general physiological adaptation of the bacterium to grow on this highly hydrophobic polycyclic compound. Nevertheless, 39 of the catabolic genes are organized in three specific clusters. These results not only supported the role of KstR and KstR2 as auto-regulated repressors of cholesterol catabolism, and revealed some metabolic similarities and differences on actinobacteria, but more important, they have facilitated the identification of new catabolic genes, opening a research scenario that might provide important clues on the role of cholesterol in tuberculosis infection.


Archive | 2007

Synthesis and Degradation of Polyhydroxyalkanoates

María Auxiliadora Prieto; Laura I. de Eugenio; Beatriz Galán; José M. Luengo; Bernard Witholt

Abbreviations: PHA: Polyhydroxyalkanoate, GAPs: Granule associated proteins, scl-PHAs: Short-chain-length PHAs, mcl-PHAs: Medium-chainlength PHAs, PHB: Polyhydroxybutyrate, CoA: Coenzyme A, ACP: Acyl carrier protein, GFP: Green fluorescent protein, P(HB-co-HA): Poly(3hydroxybutyrate-co-3-hydroxyalkanoates), PHO: Poly-3-hydroxyoctanoate, PHV: Poly-3-hydroxyvalerate, SCP: single-cell-protein.


Environmental Microbiology | 2010

The PhaD regulator controls the simultaneous expression of the pha genes involved in polyhydroxyalkanoate metabolism and turnover in Pseudomonas putida KT2442.

Laura I. de Eugenio; Beatriz Galán; Isabel F. Escapa; Beatriz Maestro; J. Sanz; José Luis García; María Auxiliadora Prieto

The promoters of the pha gene cluster encoding the enzymes involved in the metabolism of polyhydroxyalkanoates (PHAs) in the model strain Pseudomonas putida KT2442 have been identified and compared. The pha locus is composed by five functional promoters upstream the phaC1, phaZ, phaC2, phaF and phaI genes (P(C1), P(Z), P(C2), P(F) and P(I) respectively). P(C1) and P(I) are the most active promoters of the pha cluster allowing the transcription of phaC1ZC2D and phaIF operons. All promoters with the sole exception of P(F) are carbon source-dependent. Their transcription profiles explain the simultaneous production of PHA depolymerase and synthases to maintain the metabolic balance and PHA turnover. Mutagenesis analyses demonstrated that PhaD, a TetR-like transcriptional regulator, behaves as a carbon source-dependent activator of the pha cluster. The phaD gene is mainly transcribed as part of the phaC1ZC2D transcription unit and controls its own transcription and that of phaIF operon. The ability of PhaD to bind the P(C1) and P(I) promoters was analysed by gel retardation and DNase I footprinting assays, demonstrating that PhaD interacts with a region of 25 bp at P(C1) promoter (named OPRc1) and a 29 bp region at P(I) promoter (named OPRi). These operators contain a single binding site formed by two inverted half sites of 6 bp separated by 8 bp which overlap the corresponding promoter boxes. The 3D model structure of PhaD activator predicts that the true effector might be a CoA-intermediate of fatty acid beta-oxidation.


DNA Research | 2016

Whole Genome Sequencing of Turbot (Scophthalmus maximus; Pleuronectiformes): A Fish Adapted to Demersal Life

Antonio Figueras; Diego Robledo; André Corvelo; Miguel Hermida; Patricia Pereiro; Juan A. Rubiolo; Jèssica Gómez-Garrido; Laia Carreté; Xabier Bello; Marta Gut; Ivo Gut; Marina Marcet-Houben; Gabriel Forn-Cuní; Beatriz Galán; José Luis García; J. L. Abal-Fabeiro; Belén G. Pardo; Xoana Taboada; Carlos Fernández; Anna Vlasova; Antonio Hermoso-Pulido; Roderic Guigó; José Antonio Álvarez-Dios; Antonio Gómez-Tato; Ana Viñas; Xulio Maside; Toni Gabaldón; Beatriz Novoa; Carmen Bouza; Tyler Alioto

The turbot is a flatfish (Pleuronectiformes) with increasing commercial value, which has prompted active genomic research aimed at more efficient selection. Here we present the sequence and annotation of the turbot genome, which represents a milestone for both boosting breeding programmes and ascertaining the origin and diversification of flatfish. We compare the turbot genome with model fish genomes to investigate teleost chromosome evolution. We observe a conserved macrosyntenic pattern within Percomorpha and identify large syntenic blocks within the turbot genome related to the teleost genome duplication. We identify gene family expansions and positive selection of genes associated with vision and metabolism of membrane lipids, which suggests adaptation to demersal lifestyle and to cold temperatures, respectively. Our data indicate a quick evolution and diversification of flatfish to adapt to benthic life and provide clues for understanding their controversial origin. Moreover, we investigate the genomic architecture of growth, sex determination and disease resistance, key traits for understanding local adaptation and boosting turbot production, by mapping candidate genes and previously reported quantitative trait loci. The genomic architecture of these productive traits has allowed the identification of candidate genes and enriched pathways that may represent useful information for future marker-assisted selection in turbot.

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José Luis García

Spanish National Research Council

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María Auxiliadora Prieto

Spanish National Research Council

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Lorena Fernández-Cabezón

Spanish National Research Council

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Eduardo Díaz

Spanish National Research Council

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Esther García-Fernández

Spanish National Research Council

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José Luis Dader García

Complutense University of Madrid

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Isabel Manso

Spanish National Research Council

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Julia García-Fernández

Spanish National Research Council

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Isabel F. Escapa

Spanish National Research Council

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Carmen Felpeto-Santero

Spanish National Research Council

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