Pozueta Romero, Javier

person.page.identifierURI

https://academica-e.unavarra.es/handle/2454/49806

Last Name

Pozueta Romero

First Name

Javier

person.page.departamento

Instituto de Agrobiotecnología (IdAB)

ORCID

0000-0002-0335-9663

person.page.upna

2094

Full item page

Search Results

Now showing 1 - 10 of 21

Open Access
A cAMP/CRP-controlled mechanism for the incorporation of extracellular ADP-glucose in Escherichia coli involving NupC and NupG nucleoside transporters
(Nature Research, 2018) Almagro Zabalza, Goizeder; Viale Bailone, Alejandro M.; Montero Macarro, Manuel; Muñoz Pérez, Francisco José; Baroja Fernández, Edurne; Mori, Hirotada; Pozueta Romero, Javier; IdAB. Instituto de Agrobiotecnología / Agrobioteknologiako Institutua; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
ADP-glucose is the precursor of glycogen biosynthesis in bacteria, and a compound abundant in the starchy plant organs ingested by many mammals. Here we show that the enteric species Escherichia coli is capable of scavenging exogenous ADP-glucose for use as a glycosyl donor in glycogen biosynthesis and feed the adenine nucleotide pool. To unravel the molecular mechanisms involved in this process, we screened the E. coli single-gene deletion mutants of the Keio collection for glycogen content in ADP-glucose-containing culture medium. In comparison to wild-type (WT) cells, individual ∆nupC and ∆nupG mutants lacking the cAMP/CRP responsive inner-membrane nucleoside transporters NupC and NupG displayed reduced glycogen contents and slow ADP-glucose incorporation. In concordance, ∆cya and ∆crp mutants accumulated low levels of glycogen and slowly incorporated ADP-glucose. Two-thirds of the glycogen-excess mutants identified during screening lacked functions that underlie envelope biogenesis and integrity, including the RpoE specific RseA anti-sigma factor. These mutants exhibited higher ADP-glucose uptake than WT cells. The incorporation of either ∆crp, ∆nupG or ∆nupC null alleles sharply reduced the ADP-glucose incorporation and glycogen content initially witnessed in ∆rseA cells. Overall, the data showed that E. coli incorporates extracellular ADP-glucose through a cAMP/CRP-regulated process involving the NupC and NupG nucleoside transporters that is facilitated under envelope stress conditions.
Open Access
Sucrose synthase activity in the sus1/sus2/sus3/sus4 Arabidopsis mutant is sufficient to support normal cellulose and starch production
(National Academy of Sciences, 2011) Baroja Fernández, Edurne; Muñoz Pérez, Francisco José; Li, Jun; Bahaji, Abdellatif; Almagro Zabalza, Goizeder; Montero Macarro, Manuel; Etxeberria, Ed; Hidalgo Cruz, Maite; Sesma Pascual, María Teresa; Pozueta Romero, Javier; IdAB. Instituto de Agrobiotecnología / Agrobioteknologiako Institutua; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Sucrose synthase (SUS) catalyzes the reversible conversion of sucrose and a nucleoside diphosphate into the corresponding nucleoside diphosphate-glucose and fructose. In Arabidopsis, a multigene family encodes six SUS (SUS1-6) isoforms. The involvement of SUS in the synthesis of UDP-glucose and ADP-glucose linked to Arabidopsis cellulose and starch biosynthesis, respectively, has been questioned by Barratt et al. [(2009) Proc Natl Acad Sci USA 106:13124–13129], who showed that (i) SUS activity in wild type (WT) leaves is too low to account for normal rate of starch accumulation in Arabidopsis, and (ii) different organs of the sus1/sus2/sus3/sus4 SUS mutant impaired in SUS activity accumulate WT levels of ADP-glucose, UDP-glucose, cellulose and starch. However, these authors assayed SUS activity under unfavorable pH conditions for the reaction. By using favorable pH conditions for assaying SUS activity, in this work we show that SUS activity in the cleavage direction is sufficient to support normal rate of starch accumulation in WT leaves. We also demonstrate that sus1/sus2/sus3/sus4 leaves display WT SUS5 and SUS6 expression levels, whereas leaves of the sus5/sus6 mutant display WT SUS1–4 expression levels. Furthermore, we show that SUS activity in leaves and stems of the sus1/sus2/sus3/sus4 and sus5/sus6 plants is ~85% of that of WT leaves, which can support normal cellulose and starch biosynthesis. The overall data disprove Barratt et al. (2009) claims, and are consistent with the possible involvement of SUS in cellulose and starch biosynthesis in Arabidopsis.
Open Access
HPLC-MS/MS analyses show that the near-starchless aps1 and pgm leaves accumulate wild type levels of ADPglucose: further evidence for the occurrence of important ADPglucose biosynthetic pathway(s) alternative to the pPGI-pPGM-AGP pathway
(Public Library of Science, 2014) Bahaji, Abdellatif; Baroja Fernández, Edurne; Sánchez López, Ángela María; Muñoz Pérez, Francisco José; Li, Jun; Almagro Zabalza, Goizeder; Montero Macarro, Manuel; Pujol, Pablo; Galarza, Regina; Kaneko, Kentaro; Oikawa, Kazusato; Wada, Kaede; Mitsui, Toshiaki; Pozueta Romero, Javier; IdAB. Instituto de Agrobiotecnología / Agrobioteknologiako Institutua; Gobierno de Navarra / Nafarroako Gobernua, IIM010491.RI1
In leaves, it is widely assumed that starch is the end-product of a metabolic pathway exclusively taking place in the chloroplast that (a) involves plastidic phosphoglucomutase (pPGM), ADPglucose (ADPG) pyrophosphorylase (AGP) and starch synthase (SS), and (b) is linked to the Calvin-Benson cycle by means of the plastidic phosphoglucose isomerase (pPGI). This view also implies that AGP is the sole enzyme producing the starch precursor molecule, ADPG. However, mounting evidence has been compiled pointing to the occurrence of important sources, other than the pPGI-pPGM-AGP pathway, of ADPG. To further explore this possibility, in this work two independent laboratories have carried out HPLC-MS/ MS analyses of ADPG content in leaves of the near-starchless pgm and aps1 mutants impaired in pPGM and AGP, respectively, and in leaves of double aps1/pgm mutants grown under two different culture conditions. We also measured the ADPG content in wild type (WT) and aps1 leaves expressing in the plastid two different ADPG cleaving enzymes, and in aps1 leaves expressing in the plastid GlgC, a bacterial AGP. Furthermore, we measured the ADPG content in ss3/ss4/aps1 mutants impaired in starch granule initiation and chloroplastic ADPG synthesis. We found that, irrespective of their starch contents, pgm and aps1 leaves, WT and aps1 leaves expressing in the plastid ADPG cleaving enzymes, and aps1 leaves expressing in the plastid GlgC accumulate WT ADPG content. In clear contrast, ss3/ss4/aps1 leaves accumulated ca. 300 foldmore ADPG than WT leaves. The overall data showed that, in Arabidopsis leaves, (a) there are important ADPG biosynthetic pathways, other than the pPGI-pPGM-AGP pathway, (b) pPGM and AGP are not major determinants of intracellular ADPG content, and (c) the contribution of the chloroplastic ADPG pool to the total ADPG pool is low.
Open Access
Reply to Smith et al.: No evidence to challenge the current paradigm on starch and cellulose biosynthesis involving sucrose synthase activity
(National Academy of Sciences, 2012) Baroja Fernández, Edurne; Muñoz Pérez, Francisco José; Bahaji, Abdellatif; Almagro Zabalza, Goizeder; Pozueta Romero, Javier; IdAB. Instituto de Agrobiotecnología / Agrobioteknologiako Institutua
In our opinion, no pressing biological evidence has been presented by Barratt et al. to challenge the current paradigm on cellulose and starch metabolism involving SUS activity. In this context, we must emphasize that Angeles-Núñez and Tiessen have shown that SUS2 and SUS3 are required for channeling carbon toward ADP-glucose and starch in Arabidopsis seeds.
Open Access
Adenosine diphosphate sugar pyrophosphatase prevents glycogen biosynthesis in Escherichia coli
(National Academy of Sciences, 2001) Moreno Bruna, Beatriz; Baroja Fernández, Edurne; Muñoz Pérez, Francisco José; Bastarrica Berasategui, Ainara; Zandueta Criado, Aitor; Rodríguez López, Milagros; Lasa Uzcudun, Íñigo; Akazawa, Takashi; Pozueta Romero, Javier; IdAB. Instituto de Agrobiotecnología / Agrobioteknologiako Institutua
An adenosine diphosphate sugar pyrophosphatase (ASPPase, EC 3.6.1.21) has been characterized by using Escherichia coli. This enzyme, whose activities in the cell are inversely correlated with the intracellular glycogen content and the glucose concentration in the culture medium, hydrolyzes ADP-glucose, the precursor molecule of glycogen biosynthesis. ASPPase was purified to apparent homogeneity (over 3,000-fold), and sequence analyses revealed that it is a member of the ubiquitously distributed group of nucleotide pyrophosphatases designated as ‘‘nudix’’ hydrolases. Insertional mutagenesis experiments leading to the inactivation of the ASPPase encoding gene, aspP, produced cells with marginally low enzymatic activities and higher glycogen content than wildtype bacteria. aspP was cloned into an expression vector and introduced into E. coli. Transformed cells were shown to contain a dramatically reduced amount of glycogen, as compared with the untransformed bacteria. No pleiotropic changes in the bacterial growth occurred in both the aspP-overexpressing and aspP-deficient strains. The overall results pinpoint the reaction catalyzed by ASPPase as a potential step of regulating glycogen biosynthesis in E. coli.
Open Access
Most of ADP-glucose linked to starch biosynthesis occurs outside the chloroplast in source leaves
(National Academy of Sciences, 2004) Baroja Fernández, Edurne; Muñoz Pérez, Francisco José; Zandueta Criado, Aitor; Morán Zorzano, María Teresa; Viale Bailone, Alejandro M.; Alonso Casajús, Nora; Pozueta Romero, Javier; IdAB. Instituto de Agrobiotecnología / Agrobioteknologiako Institutua; Gobierno de Navarra / Nafarroako Gobernua
Sucrose and starch are end products of two segregated gluconeogenic pathways, and their production takes place in the cytosol and chloroplast of green leaves, respectively. According to this view, the plastidial ADP glucose (ADPG) pyrophosphorylase (AGP) is the sole enzyme catalyzing the synthesis of the starch precursor molecule ADPG. However, a growing body of evidences indicates that starch formation involves the import of cytosolic ADPG to the chloroplast. This evidence is consistent with the idea that synthesis of the ADPG linked to starch biosynthesis takes place in the cytosol by means of sucrose synthase, whereas AGP channels the glucose units derived from the starch breakdown. To test this hypothesis, we first investigated the subcellular localization of ADPG. Toward this end, we constructed transgenic potato plants that expressed the ADPG-cleaving adenosine diphosphate sugar pyrophosphatase (ASPP) from Escherichia coli either in the chloroplast or in the cytosol. Source leaves from plants expressing ASPP in the chloroplast exhibited reduced starch and normal ADPG content as compared with control plants. Most importantly however, leaves from plants expressing ASPP in the cytosol showed a large reduction of the levels of both ADPG and starch, whereas hexose phosphates increased as compared with control plants. No pleiotropic changes in photosynthetic parameters and maximum catalytic activities of enzymes closely linked to starch and sucrose metabolism could be detected in the leaves expressing ASPP in the cytosol. The overall results show that, essentially similar to cereal endosperms, most of the ADPG linked to starch biosynthesis in source leaves occurs in the cytosol.
Open Access
Genetic and isotope ratio mass spectrometric evidence for the occurrence of starch degradation and cycling in illuminated Arabidopsis leaves
(Public Library of Science, 2017) Baslam, Marouane; Baroja Fernández, Edurne; Ricarte Bermejo, Adriana; Sánchez López, Ángela María; Aranjuelo Michelena, Iker; Bahaji, Abdellatif; Muñoz Pérez, Francisco José; Almagro Zabalza, Goizeder; Pujol, Pablo; Galarza, Regina; Teixidor, Pilar; Pozueta Romero, Javier; IdAB. Instituto de Agrobiotecnología / Agrobioteknologiako Institutua
Although there is a great wealth of data supporting the occurrence of simultaneous synthesis and breakdown of storage carbohydrate in many organisms, previous 13CO2 pulse-chase based studies indicated that starch degradation does not operate in illuminated Arabidopsis leaves. Here we show that leaves of gwd, sex4, bam4, bam1/bam3 and amy3/isa3/lda starch breakdown mutants accumulate higher levels of starch than wild type (WT) leaves when cultured under continuous light (CL) conditions. We also show that leaves of CL grown dpe1 plants impaired in the plastidic disproportionating enzyme accumulate higher levels of maltotriose than WT leaves, the overall data providing evidence for the occurrence of extensive starch degradation in illuminated leaves. Moreover, we show that leaves of CL grown mex1/ pglct plants impaired in the chloroplastic maltose and glucose transporters display a severe dwarf phenotype and accumulate high levels of maltose, strongly indicating that the MEX1 and pGlcT transporters are involved in the export of starch breakdown products to the cytosol to support growth during illumination. To investigate whether starch breakdown products can be recycled back to starch during illumination through a mechanism involving ADP-glucose pyrophosphorylase (AGP) we conducted kinetic analyses of the stable isotope carbon composition (δ13C) in starch of leaves of 13CO2 pulsed-chased WT and AGP lacking aps1 plants. Notably, the rate of increase of δ13C in starch of aps1 leaves during the pulse was exceedingly higher than that of WT leaves. Furthermore, δ13C decline in starch of aps1 leaves during the chase was much faster than that of WT leaves, which provides strong evidence for the occurrence of AGP-mediated cycling of starch breakdown products in illuminated Arabidopsis leaves.
Open Access
Volatile compounds emitted by diverse phytopathogenic microorganisms promote plant growth and flowering through cytokinin action
(John Wiley & Sons, 2016) Sánchez López, Ángela María; Baslam, Marouane; Muñoz Pérez, Francisco José; Bahaji, Abdellatif; Almagro Zabalza, Goizeder; Ricarte Bermejo, Adriana; García Gómez, Pablo; Baroja Fernández, Edurne; Pozueta Romero, Javier; IdAB. Instituto de Agrobiotecnología / Agrobioteknologiako Institutua; Gobierno de Navarra / Nafarroako Gobernua (IIM010491.RI1); Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
It is known that volatile emissions from some beneﬁcial rhizosphere microorganisms promote plant growth. Here we show that volatile compounds (VCs) emitted by phylogenetically diverse rhizosphere and non-rhizhosphere bacteria and fungi (including plant pathogens and microbes that do not normally interact mutualistically with plants) promote growth and ﬂowering of various plant species, including crops. In Arabidopsis plants exposed to VCs emitted by the phytopathogen Alternaria alternata, changes included enhancement of photosynthesis and accumulation of high levels of cytokinins (CKs) and sugars. Evidence obtained using transgenic Arabidopsis plants with altered CK status show that CKs play essential roles in this phenomenon, because growth and ﬂowering responses to the VCs were reduced in mutants with CK-deﬁciency (35S:AtCKX1) or low receptor sensitivity (ahk2/3). Further, we demonstrate that the plant responses to fungal VCs are light-dependent. Transcriptomic analyses of Arabidopsis leaves exposed to A. alternata VCs revealed changes in the expression of light- and CK-responsive genes involved in photosynthesis, growth and ﬂowering. Notably, many genes differentially expressed in plants treated with fungal VCs were also differentially expressed in plants exposed to VCs emitted by the plant growth promoting rhizobacterium Bacillus subtilis GB03, suggesting that plants react to microbial VCs through highly conserved regulatory mechanisms.
Open Access
Enhancing the expression of starch synthase class IV results in increased levels of both transitory and long-term storage starch
(Wiley, 2011) Gámez-Arjona, Francisco M.; Li, Jun; Raynaud, Sandy; Baroja Fernández, Edurne; Muñoz Pérez, Francisco José; Ovecka, Miroslav; Ragel, Paula; Bahaji, Abdellatif; Pozueta Romero, Javier; Mérida, Ángel; IdAB. Instituto de Agrobiotecnología / Agrobioteknologiako Institutua
Starch is an important renewable raw material with an increasing number of applications. Several attempts have been made to obtain plants that produce modified versions of starch or higher starch yield. Most of the approaches designed to increase the levels of starch have focused on the increment of the amount of ADP‐glucose or ATP available for starch biosynthesis. In this work, we show that the overexpression of starch synthase class IV (SSIV) increases the levels of starch accumulated in the leaves of Arabidopsis by 30%–40%. In addition, SSIV‐overexpressing lines display a higher rate of growth. The increase in starch content as a consequence of enhanced SSIV expression is also observed in long‐term storage starch organs such as potato tubers. Overexpression of SSIV in potato leads to increased tuber starch content on a dry weight basis and to increased yield of starch production in terms of tons of starch/hectare. These results identify SSIV as one of the regulatory steps involved in the control of the amount of starch accumulated in plastids.
Open Access
Plastidial phosphoglucose isomerase is an important determinant of seed yield through its involvement in gibberellin-mediated reproductive development and storage reserve biosynthesis in arabidopsis
(American Society of Plant Biologists, 2018) Bahaji, Abdellatif; Almagro Zabalza, Goizeder; Ezquer, Ignacio; Gámez Arcas, Samuel; Sánchez López, Ángela María; Muñoz Pérez, Francisco José; Barrio, Ramón José; Sampedro, M. Carmen; Diego, Nuria de; Spíchal, Lukás; Dolezal, Karel; Tarkowská, Danuse; Caporali, Elisabetta; Mendes, Marta Adelina; Baroja Fernández, Edurne; Pozueta Romero, Javier; IdAB. Instituto de Agrobiotecnología / Agrobioteknologiako Institutua; Gobierno de Navarra / Nafarroako Gobernua, ref. P1004 PROMEBIO
The plastid-localized phosphoglucose isomerase isoform PGI1 is an important determinant of growth in Arabidopsis thaliana, likely due to its involvement in the biosynthesis of plastidial isoprenoid-derived hormones. Here, we investigated whether PGI1 also influences seed yields. PGI1 is strongly expressed in maturing seed embryos and vascular tissues. PGI1-null pgi1-2 plants had ∼60% lower seed yields than wild-type plants, with reduced numbers of inflorescences and thus fewer siliques and seeds per plant. These traits were associated with low bioactive gibberellin (GA) contents. Accordingly, wild-type phe-notypes were restored by exogenous GA application. pgi1-2 seeds were lighter and accumulated ∼50% less fatty acids (FAs) and ∼35% less protein than wild-type seeds. Seeds of cytokinin-deficient plants overexpressing CYTOKININ OXIDASE/DE-HYDROGENASE1 (35S:AtCKX1) and GA-deficient ga20ox1 ga20ox2 mutants did not accumulate low levels of FAs, and exogenous application of the cytokinin 6-benzylaminopurine and GAs did not rescue the reduced weight and FA content of pgi1-2 seeds. Seeds from reciprocal crosses between pgi1-2 and wild-type plants accumulated wild-type levels of FAs and proteins. Therefore, PGI1 is an important determinant of Arabidopsis seed yield due to its involvement in two processes: GA-mediated reproductive development and the metabolic conversion of plastidial glucose-6-phosphate to storage reserves in the embryo.