Intermolecular displacement of S-bound L-methionine on platinum(II) by guanosine 5′-monophosphate: Implications for the mechanism of action of anticancer drugs

NMR investigations of the kinetics and thermodynamics of the competitive binding of L-methionine (Met), L-histidine (His), and 5′-monophosphates of guanosine (5′-GMP), adenosine (5′-AMP), thymidine (5′-TMP) and cytidine (5′-CMP) to [Pt(dien)Cl]+ (dien = 1,5-diamino-3-azapentane) in aqueous solution show that 5′-GMP selectively displaces S-bound Met, a finding which has implications for DNA platination by anticancer drugs in vivo

Two parallel pathways connect glutamine metabolism and mTORC1 activity to regulate glutamoptosis

Glutamoptosis is the induction of apoptotic cell death as a consequence of the aberrant activation of glutaminolysis and mTORC1 signaling during nutritional imbalance in proliferating cells. The role of the bioenergetic sensor AMPK during glutamoptosis is not defined yet. Here, we show that AMPK reactivation blocks both the glutamine-dependent activation of mTORC1 and glutamoptosis in vitro and in vivo. We also show that glutamine is used for asparagine synthesis and the GABA shunt to produce ATP and to inhibit AMPK, independently of glutaminolysis. Overall, our results indicate that glutamine metabolism is connected with mTORC1 activation through two parallel pathways: an acute alpha-ketoglutarate-dependent pathway; and a secondary ATP/AMPK-dependent pathway. This dual metabolic connection between glutamine and mTORC1 must be considered for the future design of therapeutic strategies to prevent cell growth in diseases such as cancer.Unión Europea(PGC2018-096244- B-I00, SAF2016-75442-R

Exopolysaccharide Production by Sinorhizobium fredii HH103 Is Repressed by Genistein in a NodD1-Dependent Manner

In the rhizobia-legume symbiotic interaction, bacterial surface polysaccharides, such as exopolysaccharide (EPS), lipopolysaccharide (LPS), K-antigen polysaccharide (KPS) or cyclic glucans (CG), appear to play crucial roles either acting as signals required for the progression of the interaction and/or preventing host defence mechanisms. The symbiotic significance of each of these polysaccharides varies depending on the specific rhizobialegume couple. In this work we show that the production of exopolysaccharide by Sinorhizobium fredii HH103, but not by other S. fredii strains such as USDA257 or NGR234, is repressed by nod gene inducing flavonoids such as genistein and that this repression is dependent on the presence of a functional NodD1 protein. In agreement with the importance of EPS for bacterial biofilms, this reduced EPS production upon treatment with flavonoids correlates with decreased biofilm formation ability. By using quantitative RT-PCR analysis we show that expression of the exoY2 and exoK genes is repressed in late stationary cultures of S. fredii HH103 upon treatment with genistein. Results presented in this work show that in S. fredii HH103 EPS production is regulated just in the opposite way than other bacterial signals such as Nod factors and type 3 secreted effectors: it is repressed by flavonoids and NodD1 and enhanced by the nod repressor NolR. These results are in agreement with our previous observations showing that lack of EPS production by S. fredii HH103 is not only non-detrimental but even beneficial for symbiosis with soybeanMinisterio de Ciencia e Investigación BIO2011-30229-C02-01Junta de Andalucía P11-CVI-750

Two parallel pathways connect glutamine metabolism and mTORC1 activity to regulate glutamoptosis.

Glutamoptosis is the induction of apoptotic cell death as a consequence of the aberrant activation of glutaminolysis and mTORC1 signaling during nutritional imbalance in proliferating cells. The role of the bioenergetic sensor AMPK during glutamoptosis is not defined yet. Here, we show that AMPK reactivation blocks both the glutamine-dependent activation of mTORC1 and glutamoptosis in vitro and in vivo. We also show that glutamine is used for asparagine synthesis and the GABA shunt to produce ATP and to inhibit AMPK, independently of glutaminolysis. Overall, our results indicate that glutamine metabolism is connected with mTORC1 activation through two parallel pathways: an acute alpha-ketoglutarate-dependent pathway; and a secondary ATP/AMPK-dependent pathway. This dual metabolic connection between glutamine and mTORC1 must be considered for the future design of therapeutic strategies to prevent cell growth in diseases such as cancer.This work was supported by funds from the following institutions: Agencia Estatal de Investigación/European Regional Development Fund, European Union (PGC2018-096244- B-I00, SAF2016-75442-R), Ministry of Science, Innovation and Universities of Spain, Spanish National Research Council—CSIC, Institut National de la Santé et de la Recherche Médicale —INSERM, Université de Bordeaux, Fondation pour la Recherche Médicale, the Conseil Régional d’Aquitaine, SIRIC-BRIO, Fondation ARC, and Institut Européen de Chimie et Biologie. C.B. was recipient of fellowships from the Minister of Higher Education, Research and Innovation (France) and the Fondation ARC (France). We thank Prof. Patricia Boya (Centro de Investigaciones Biologicas, Madrid, Spain) for kindly providing with the ATG5+/+ and ATG5−/− MEFs. We thank Prof. Benoit Viollet (Institute Cochin, Paris, France) for kindly providing with the AMPK+/+ and AMPK−/− MEFs, and the CA-AMPK plasmid

The rkpU gene of Sinorhizobium fredii HH103 is required for bacterial K-antigen polysaccharide production and for efficient nodulation with soybean but not with cowpea

In this work, the role of the rkpU and rkpJ genes in the production of the K-antigen polysaccharides (KPS) and in the symbiotic capacity of Sinorhizobium fredii HH103, a broad host-range rhizobial strain able to nodulate soybean and many other legumes, was studied. The rkpJ- and rkpU-encoded products are orthologous to Escherichia coli proteins involved in capsule export. S. fredii HH103 mutant derivatives were contructed in both genes. To our knowledge, this is the first time that the role of rkpU in KPS production has been studied in rhizobia. Both rkpJ and rkpU mutants were unable to produce KPS. The rkpU derivative also showed alterations in its lipopolysaccharide (LPS). Neither KPS production nor rkpJ and rkpU expression was affected by the presence of the flavonoid genistein. Soybean (Glycine max) plants inoculated with the S. fredii HH103 rkpU and rkpJ mutants showed reduced nodulation and clear symptoms of nitrogen starvation. However, neither the rkpJ nor the rkpU mutants were significantly impaired in their symbiotic interaction with cowpea (Vigna unguiculata). Thus, we demonstrate for the first time to our knowledge the involvement of the rkpU gene in rhizobial KPS production and also show that the symbiotic relevance of the S. fredii HH103 KPS depends on the specific bacterium–legume interaction

Downregulation of Glutamine Synthetase, not glutaminolysis, is responsible for glutamine addiction in Notch1-driven acute lymphoblastic leukemia

International audienc

Glutamine, MTOR and autophagy: a multiconnection relationship.

Cancer cells metabolize glutamine mostly through glutaminolysis, a metabolic pathway that activates MTORC1. The AMPK-MTORC1 signaling axis is a key regulator of cell growth and proliferation. Our recent investigation identified that the connection between glutamine and AMPK is not restricted to glutaminolysis. Rather, we demonstrated the crucial role of ASNS (asparagine synthetase (glutamine-hydrolyzing)) and the GABA shunt for the metabolic control of the AMPK-MTORC1 axis during glutamine sufficiency. Our results elucidated a metabolic network by which glutamine metabolism regulates the MTORC1-macroautophagy/autophagy pathway through two independent branches involving glutaminolysis and ASNS-GABA shunt.Abbreviations: αKG: alpha-ketoglutarate; AMPK: AMP-activated protein kinase; ASNS: asparagine synthetase (glutamine-hydrolyzing); GLUD/GDH: glutamate dehydrogenase; GLS: glutaminase; GOT1: glutamic-oxaloacetic transaminase 1; MTORC1: mechanistic target of rapamycin kinase complex 1; TCA: tricarboxylic acid

The Sinorhizobium (Ensifer) fredii HH103 rkp-2 region is involved in the biosynthesis of lipopolysaccharide and exopolysaccharide but not in K-antigen polysaccharide production

et al.[Background]: Rhizobial surface polysaccharides are important molecular determinants required for successful symbiosis with legumes. In Sinorhizobium (Ensifer) meliloti Rm41, the rkp-2 region is involved in the biosynthesis of K-antigen polysaccharide (KPS) and lipopolysaccharide (LPS). This region is composed of two genes, lpsL and rkpK, which are respectively responsible for the production of galacturonic and glucuronic acid. [Results]: In this work, we show that in S. (Ensifer) fredii HH103 these genes do not form a transcriptional unit and that the transcriptional rate of rkpK is much higher than that of lpsL. Inactivation of each of these genes resulted in alterations in LPS, but did not affect KPS production, which is in agreement with the lack of uronic acids in S. fredii HH103 KPS. Mutation of rkpK also impaired HH103 exopolysaccharide (EPS) production, most probably due to the presence of glucuronic acid in HH103 EPS, as well as increased bacterial autoaggregation and osmosensitivity and decreased biofilm formation on plastic surfaces. Inactivation of rkpK affected negatively symbiosis with cowpea but not with soybean. Mutation of lpsL led to a complete symbiotic impairment with cowpea, whereas soybean plants inoculated with this mutant only formed pseudonodules. In both plants, the lpsL mutant showed defects in root infection. [Conclusion]: These results confirm the symbiotic importance of HH103 LPS in symbiosis with legumes.This work was supported by grants from the Spanish Ministry of Science and Innovation (BIO2011-30229 and BIO2016-78409-R) and the Andalusia Government (P07-CVI07500). SAJ and PNG are recipients of PhD grants from the VPPI of the University of Seville.Peer Reviewe

Developmental defects in a Caenorhabditis elegans model for type III galactosemia

Type III galactosemia is a metabolic disorder caused by reduced activity of UDP-galactose-4-epimerase, which participates in galactose metabolism and the generation of various UDP-sugar species. We characterized gale-1 in Caenorhabditis elegans and found that a complete loss-of-function mutation is lethal, as has been hypothesized for humans, whereas a nonlethal partial loss-offunction allele causes a variety of developmental abnormalities, likely resulting from the impairment of the glycosylation process. We also observed that gale-1 mutants are hypersensitive to galactose as well as to infections. Interestingly, we found interactions between gale-1 and the unfolded protein response.This work was supported by the Junta de Andalucía (P07-CVI-02697) and the Spanish Ministry of Science and Innovation (BFU2006-07391/BMC) and Ministry of Economy and Competitiveness (BFU2013-46923-P). A.M.B.-L. was supported by a Plan Propio de Investigación fellowship from the Universidad Pablo de Olavide. J.M.M. was supported by the Formación del personal Universitario program of the Spanish Ministry of Science and Innovation.Peer Reviewe

Sugar and longevity in gale-1 mutant

Resumen del trabajo presentado al 4th Spanish Worm Meeting, celebrado en Carmona (Sevilla) del 14 al 15 de marzo de 2013.A reduction of food intake without malnutrition increases longevity in almost any of the model animals where have been tested. In order to understand this process our group has isolated a collection of mutants that are long lived even in normal diet. One of those mutants is gale-1(pv18) which encoded to a UDP-4-galactosa-epimerase. This mutant, in addition to be long lived, show morphological organ defects, probably due to an alteration in the concentration of UDP-sugars. In humans, mutation in the homologue gene to gale-1 generate a rare disease known as galactosemia type III, the characterization of this mutant may help to better understand this disease in humans.Peer Reviewe