Fernando Molina-Heredia - Academia.edu (original) (raw)
Papers by Fernando Molina-Heredia
Advances in Photosynthesis and Respiration
... In Page 6. 688 Miguel A. De la Rosa, Fernando P. Molina-Heredia, Manuel Hervás and José A. Na... more ... In Page 6. 688 Miguel A. De la Rosa, Fernando P. Molina-Heredia, Manuel Hervás and José A. Navarro ... membrane-embedded partners, PS I and cytochrome b6 f (Frazao et al., 1995; Ubbink et al., 1998; Crowley et al., 2002; Dıaz-Quintana et al., 2003; Dıaz-Moreno et al ...
Proceedings of the National Academy of Sciences, 2006
The superoxide radical O 2 ·̅ is a toxic by-product of oxygen metabolism. Two O 2 ·̅ detoxifying ... more The superoxide radical O 2 ·̅ is a toxic by-product of oxygen metabolism. Two O 2 ·̅ detoxifying enzymes have been described so far, superoxide dismutase and superoxide reductase (SOR), both forming H 2 O 2 as a reaction product. Recently, the SOR active site, a ferrous iron in a [Fe 2+ (N-His) 4 (S-Cys)] pentacoordination, was shown to have the ability to form a complex with the organometallic compound ferrocyanide. Here, we have investigated in detail the reactivity of the SOR–ferrocyanide complex with O 2 ·̅ by pulse and γ-ray radiolysis, infrared, and UV-visible spectroscopies. The complex reacts very efficiently with O 2 ·̅ . However, the presence of the ferrocyanide adduct markedly modifies the reaction mechanism of SOR, with the formation of transient intermediates different from those observed for SOR alone. A one-electron redox chemistry appears to be carried out by the ferrocyanide moiety of the complex, whereas the SOR iron site remains in the reduced state. Surprisingly,...
Physical Chemistry Chemical Physics, 2009
Biochemistry, 2005
Oxidation of the soluble, truncated form of cytochrome f by wild-type and mutant species of plast... more Oxidation of the soluble, truncated form of cytochrome f by wild-type and mutant species of plastocyanin has been analyzed by laser flash absorption spectroscopy in the cyanobacterium Nostoc (formerly, Anabaena) sp. PCC 7119. At low ionic strengths, the apparent electron transfer rate constant of cytochrome f oxidation by wild-type plastocyanin is 1.34 x 10(4) s(-)(1), a value much larger than those determined for the same proteins from other organisms. Upon site-directed mutagenesis of specific residues at the plastocyanin interaction area, the rate constant decreases in all cases yet to varying extents. The only exception is the D54K variant, which exhibits a higher reactivity toward cytochrome f. In most cases, the reaction rate constant decreases monotonically with an increase in ionic strength. The observed changes in the reaction mechanism and rate constants are in agreement with the location of the mutated residues at the interface area, as well as with the peculiar orientation of the two partners within the Nostoc plastocyanin-cytochrome f transient complex, whose NMR structure has been determined recently. Furthermore, the experimental data herein reported match well the kinetic behavior exhibited by the same set of plastocyanin mutants when acting as donors of electrons to photosystem I [Molina-Heredia, F. P., et al. (2001) J. Biol. Chem. 276, 601-605], thus indicating that the copper protein uses the same surface areas-one hydrophobic and the other electrostatic-to interact with both cytochrome f and photosystem I.
Biochemical and Biophysical Research Communications, 2006
Two synthetic genes coding for human and Arabidopsis cytochrome c, respectively, have been design... more Two synthetic genes coding for human and Arabidopsis cytochrome c, respectively, have been designed and constructed, and the recombinant proteins have been over-expressed in Escherichia coli cells. Thus a comparative analysis of the two heme proteins, including horse cytochrome c as a reference, has been performed. In addition to their physico-chemical properties, the redox behavior of the three proteins has been analyzed by following the kinetics of both their reduction by flavin semiquinones (lumiflavin, riboflavin, and FMN) and oxidation by cytochrome c oxidase. The resulting data indicate that the accessibility and electrostatic charge of the active site do not differ in a significant way among the three proteins, but human cytochrome c exhibits some intriguing differences when interacting with cytochrome c oxidase that could be related to the amino acid changes underwent by the latter along evolution.
Applied Microbiology and Biotechnology, 2009
Acta Crystallographica Section A Foundations of Crystallography, 2004
Biochimica et Biophysica Acta (BBA) - Bioenergetics, 2004
Cytochrome c 6 (cytc 6) from Arabidopsis differs from the cyanobacterial and algal homologues in ... more Cytochrome c 6 (cytc 6) from Arabidopsis differs from the cyanobacterial and algal homologues in several redox properties. It is possible that these differences might be due to the presence of a 12 amino acid residue loop extension common to higher plant cytc 6 proteins. However, homology modelling suggests this is not the case. We report experiments to test if differences in biochemical properties could be due to this extension. Analysis of mutant forms of Arabidopsis cytc 6 in which the entire extension was lacking, or a pair of cysteine residues in the extension had been exchanged for serine, revealed no significant effect of these changes on either the redox potential of the haem group or the reactivity towards Photosystem I (PSI). We conclude that the differences in properties are due to more subtle unidentified differences in structure, and that the sequence extension in the higher plant proteins has a function yet to be identified.
Applied Sciences
Current agricultural productivity depends on an exogenous nutrient supply to crops. This is of sp... more Current agricultural productivity depends on an exogenous nutrient supply to crops. This is of special relevance in cereal production, a fundamental part of the trophic chain that plays a vital role in the human diet. However, our agricultural practices entail highly detrimental side-effects from an environmental point of view. Long-term nitrogen fertilization in croplands results in degradation of soil, water, and air quality, producing eutrophication and subsequently contributing to global warming. In accordance with this, there is a biotechnological interest in using nitrogen-fixing microorganisms to enhance crop growth without adding chemically synthesized nitrogen fertilizers. This is particularly beneficial in paddy fields, where about 60% of the synthetic fertilizer that has been applied is dissolved in the water and washed away. In these agricultural systems, N2-fixing cyanobacteria show a promising biotechnological potential as biofertilizers, improving soil fertility while...
Molecular Plant-Microbe Interactions®
Cyanobacteria are phototrophic microorganisms able to establish nitrogen-fixing symbiotic associa... more Cyanobacteria are phototrophic microorganisms able to establish nitrogen-fixing symbiotic associations with representatives of all four of the major phylogenetic divisions of terrestrial plants. Despite increasing knowledge on the beneficial effects of cyanobacteria in rice fields, the information about the interaction between these microorganisms and rice at the molecular and structural levels is still limited. We have used the model nitrogen-fixing cyanobacterium Nostoc punctiforme to promote a long-term stable endophytic association with rice. Inoculation with this strain of hydroponic cultures of rice produces a fast adherence of the cyanobacterium to rice roots. At longer times, cyanobacterial growth in the proximity of the roots increased until reaching a plateau. This latter phase coincides with the intracellular colonization of the root epidermis and exodermis. Structural analysis of the roots revealed that the cyanobacterium use an apoplastic route to colonize the plant cel...
Biochimica et Biophysica Acta (BBA) - Bioenergetics
Thylakoidal lumen! Cytochrome c 6 is the main respiratory and photosynthetic soluble electron don... more Thylakoidal lumen! Cytochrome c 6 is the main respiratory and photosynthetic soluble electron donor in heterocysts of the cyanobacterium Anabaena sp. PCC
Biotechnology for biofuels, 2017
Modern biorefineries require enzymatic cocktails of improved efficiency to generate fermentable s... more Modern biorefineries require enzymatic cocktails of improved efficiency to generate fermentable sugars from lignocellulosic biomass. Cellulolytic fungi, among other microorganisms, have demonstrated the highest potential in terms of enzymatic productivity, complexity and efficiency. On the other hand, under cellulolytic-inducing conditions, they often produce a considerable diversity of carbohydrate-active enzymes which allow them to adapt to changing environmental conditions. However, industrial conditions are fixed and adjusted to the optimum of the whole cocktail, resulting in underperformance of individual enzymes. One of these cellulolytic cocktails from Myceliophthora thermophila has been analyzed here by means of LC-MS/MS. Pure GH6 family members detected have been characterized, confirming previous studies, and added to whole cocktails to compare their contribution in the hydrolysis of industrial substrates. Finally, independent deletions of two GH6 family members, as an exa...
Biotechnology for biofuels, 2016
To reduce the cost of the enzymes for the hydrolysis of lignocellulosic biomass, two main strateg... more To reduce the cost of the enzymes for the hydrolysis of lignocellulosic biomass, two main strategies have been followed: one, the reduction of enzyme dosing by the use of more efficient and stable enzymatic cocktails; another, to include accessory enzymes in the cocktails to increase yields by reducing the recalcitrant carbohydrate fraction remaining at the end of the process. To guide this second strategy, we have explored the chemical bond composition of different fractions of recalcitrant carbohydrates after enzymatic hydrolysis. Two lignocellulosic feedstocks of relevance for the biofuels industry have been analyzed, corn stover and sugarcane straw. On comparing the composition of chemical bonds of the starting pretreated material with samples after standard and forced hydrolysis (with enzyme overdosing), we obtained similar sugar and chemical bond composition. This suggests that the current enzymatic cocktails bear the set of enzymes needed to hydrolyze these feedstocks. From o...
Books in Soils, Plants, and the Environment, 2016
Plant and Cell Physiology, 2016
Cyt, cytochrome; Cox, cytochrome c oxidase; E m , midpoint redox potential; Em,7, midpoint redox ... more Cyt, cytochrome; Cox, cytochrome c oxidase; E m , midpoint redox potential; Em,7, midpoint redox potential at pH 7; GFP, green fluorescent protein; k bim , second-order rate constant; k inf , second-order rate constant extrapolated to infinite ionic strength; k obs , observed pseudo-first-order rate constant; ORF, open reading frame; Pc, plastocyanin; pI, isoelectric point; PSI, photosystem I.
Biochemical and Biophysical Research Communications, 2006
Two synthetic genes coding for human and Arabidopsis cytochrome c, respectively, have been design... more Two synthetic genes coding for human and Arabidopsis cytochrome c, respectively, have been designed and constructed, and the recombinant proteins have been over-expressed in Escherichia coli cells. Thus a comparative analysis of the two heme proteins, including horse cytochrome c as a reference, has been performed. In addition to their physico-chemical properties, the redox behavior of the three proteins has been analyzed by following the kinetics of both their reduction by flavin semiquinones (lumiflavin, riboflavin, and FMN) and oxidation by cytochrome c oxidase. The resulting data indicate that the accessibility and electrostatic charge of the active site do not differ in a significant way among the three proteins, but human cytochrome c exhibits some intriguing differences when interacting with cytochrome c oxidase that could be related to the amino acid changes underwent by the latter along evolution.
J Biol Chem, 2000
Positively charged plastocyanin from Anabaena sp. PCC 7119 was investigated by site-directed muta... more Positively charged plastocyanin from Anabaena sp. PCC 7119 was investigated by site-directed mutagenesis. The reactivity of its mutants toward photosystem I was analyzed by laser flash spectroscopy. Replacement of arginine at position 88, which is adjacent to the copper ligand His-87, by glutamine and, in particular, by glutamate makes plastocyanin reduce its availability for transferring electrons to photosystem I. Such a residue in the copper protein thus appears to be isofunctional with Arg-64 (which is close to the heme group) in cytochrome c 6 from Anabaena (
Advances in Photosynthesis and Respiration
... In Page 6. 688 Miguel A. De la Rosa, Fernando P. Molina-Heredia, Manuel Hervás and José A. Na... more ... In Page 6. 688 Miguel A. De la Rosa, Fernando P. Molina-Heredia, Manuel Hervás and José A. Navarro ... membrane-embedded partners, PS I and cytochrome b6 f (Frazao et al., 1995; Ubbink et al., 1998; Crowley et al., 2002; Dıaz-Quintana et al., 2003; Dıaz-Moreno et al ...
Proceedings of the National Academy of Sciences, 2006
The superoxide radical O 2 ·̅ is a toxic by-product of oxygen metabolism. Two O 2 ·̅ detoxifying ... more The superoxide radical O 2 ·̅ is a toxic by-product of oxygen metabolism. Two O 2 ·̅ detoxifying enzymes have been described so far, superoxide dismutase and superoxide reductase (SOR), both forming H 2 O 2 as a reaction product. Recently, the SOR active site, a ferrous iron in a [Fe 2+ (N-His) 4 (S-Cys)] pentacoordination, was shown to have the ability to form a complex with the organometallic compound ferrocyanide. Here, we have investigated in detail the reactivity of the SOR–ferrocyanide complex with O 2 ·̅ by pulse and γ-ray radiolysis, infrared, and UV-visible spectroscopies. The complex reacts very efficiently with O 2 ·̅ . However, the presence of the ferrocyanide adduct markedly modifies the reaction mechanism of SOR, with the formation of transient intermediates different from those observed for SOR alone. A one-electron redox chemistry appears to be carried out by the ferrocyanide moiety of the complex, whereas the SOR iron site remains in the reduced state. Surprisingly,...
Physical Chemistry Chemical Physics, 2009
Biochemistry, 2005
Oxidation of the soluble, truncated form of cytochrome f by wild-type and mutant species of plast... more Oxidation of the soluble, truncated form of cytochrome f by wild-type and mutant species of plastocyanin has been analyzed by laser flash absorption spectroscopy in the cyanobacterium Nostoc (formerly, Anabaena) sp. PCC 7119. At low ionic strengths, the apparent electron transfer rate constant of cytochrome f oxidation by wild-type plastocyanin is 1.34 x 10(4) s(-)(1), a value much larger than those determined for the same proteins from other organisms. Upon site-directed mutagenesis of specific residues at the plastocyanin interaction area, the rate constant decreases in all cases yet to varying extents. The only exception is the D54K variant, which exhibits a higher reactivity toward cytochrome f. In most cases, the reaction rate constant decreases monotonically with an increase in ionic strength. The observed changes in the reaction mechanism and rate constants are in agreement with the location of the mutated residues at the interface area, as well as with the peculiar orientation of the two partners within the Nostoc plastocyanin-cytochrome f transient complex, whose NMR structure has been determined recently. Furthermore, the experimental data herein reported match well the kinetic behavior exhibited by the same set of plastocyanin mutants when acting as donors of electrons to photosystem I [Molina-Heredia, F. P., et al. (2001) J. Biol. Chem. 276, 601-605], thus indicating that the copper protein uses the same surface areas-one hydrophobic and the other electrostatic-to interact with both cytochrome f and photosystem I.
Biochemical and Biophysical Research Communications, 2006
Two synthetic genes coding for human and Arabidopsis cytochrome c, respectively, have been design... more Two synthetic genes coding for human and Arabidopsis cytochrome c, respectively, have been designed and constructed, and the recombinant proteins have been over-expressed in Escherichia coli cells. Thus a comparative analysis of the two heme proteins, including horse cytochrome c as a reference, has been performed. In addition to their physico-chemical properties, the redox behavior of the three proteins has been analyzed by following the kinetics of both their reduction by flavin semiquinones (lumiflavin, riboflavin, and FMN) and oxidation by cytochrome c oxidase. The resulting data indicate that the accessibility and electrostatic charge of the active site do not differ in a significant way among the three proteins, but human cytochrome c exhibits some intriguing differences when interacting with cytochrome c oxidase that could be related to the amino acid changes underwent by the latter along evolution.
Applied Microbiology and Biotechnology, 2009
Acta Crystallographica Section A Foundations of Crystallography, 2004
Biochimica et Biophysica Acta (BBA) - Bioenergetics, 2004
Cytochrome c 6 (cytc 6) from Arabidopsis differs from the cyanobacterial and algal homologues in ... more Cytochrome c 6 (cytc 6) from Arabidopsis differs from the cyanobacterial and algal homologues in several redox properties. It is possible that these differences might be due to the presence of a 12 amino acid residue loop extension common to higher plant cytc 6 proteins. However, homology modelling suggests this is not the case. We report experiments to test if differences in biochemical properties could be due to this extension. Analysis of mutant forms of Arabidopsis cytc 6 in which the entire extension was lacking, or a pair of cysteine residues in the extension had been exchanged for serine, revealed no significant effect of these changes on either the redox potential of the haem group or the reactivity towards Photosystem I (PSI). We conclude that the differences in properties are due to more subtle unidentified differences in structure, and that the sequence extension in the higher plant proteins has a function yet to be identified.
Applied Sciences
Current agricultural productivity depends on an exogenous nutrient supply to crops. This is of sp... more Current agricultural productivity depends on an exogenous nutrient supply to crops. This is of special relevance in cereal production, a fundamental part of the trophic chain that plays a vital role in the human diet. However, our agricultural practices entail highly detrimental side-effects from an environmental point of view. Long-term nitrogen fertilization in croplands results in degradation of soil, water, and air quality, producing eutrophication and subsequently contributing to global warming. In accordance with this, there is a biotechnological interest in using nitrogen-fixing microorganisms to enhance crop growth without adding chemically synthesized nitrogen fertilizers. This is particularly beneficial in paddy fields, where about 60% of the synthetic fertilizer that has been applied is dissolved in the water and washed away. In these agricultural systems, N2-fixing cyanobacteria show a promising biotechnological potential as biofertilizers, improving soil fertility while...
Molecular Plant-Microbe Interactions®
Cyanobacteria are phototrophic microorganisms able to establish nitrogen-fixing symbiotic associa... more Cyanobacteria are phototrophic microorganisms able to establish nitrogen-fixing symbiotic associations with representatives of all four of the major phylogenetic divisions of terrestrial plants. Despite increasing knowledge on the beneficial effects of cyanobacteria in rice fields, the information about the interaction between these microorganisms and rice at the molecular and structural levels is still limited. We have used the model nitrogen-fixing cyanobacterium Nostoc punctiforme to promote a long-term stable endophytic association with rice. Inoculation with this strain of hydroponic cultures of rice produces a fast adherence of the cyanobacterium to rice roots. At longer times, cyanobacterial growth in the proximity of the roots increased until reaching a plateau. This latter phase coincides with the intracellular colonization of the root epidermis and exodermis. Structural analysis of the roots revealed that the cyanobacterium use an apoplastic route to colonize the plant cel...
Biochimica et Biophysica Acta (BBA) - Bioenergetics
Thylakoidal lumen! Cytochrome c 6 is the main respiratory and photosynthetic soluble electron don... more Thylakoidal lumen! Cytochrome c 6 is the main respiratory and photosynthetic soluble electron donor in heterocysts of the cyanobacterium Anabaena sp. PCC
Biotechnology for biofuels, 2017
Modern biorefineries require enzymatic cocktails of improved efficiency to generate fermentable s... more Modern biorefineries require enzymatic cocktails of improved efficiency to generate fermentable sugars from lignocellulosic biomass. Cellulolytic fungi, among other microorganisms, have demonstrated the highest potential in terms of enzymatic productivity, complexity and efficiency. On the other hand, under cellulolytic-inducing conditions, they often produce a considerable diversity of carbohydrate-active enzymes which allow them to adapt to changing environmental conditions. However, industrial conditions are fixed and adjusted to the optimum of the whole cocktail, resulting in underperformance of individual enzymes. One of these cellulolytic cocktails from Myceliophthora thermophila has been analyzed here by means of LC-MS/MS. Pure GH6 family members detected have been characterized, confirming previous studies, and added to whole cocktails to compare their contribution in the hydrolysis of industrial substrates. Finally, independent deletions of two GH6 family members, as an exa...
Biotechnology for biofuels, 2016
To reduce the cost of the enzymes for the hydrolysis of lignocellulosic biomass, two main strateg... more To reduce the cost of the enzymes for the hydrolysis of lignocellulosic biomass, two main strategies have been followed: one, the reduction of enzyme dosing by the use of more efficient and stable enzymatic cocktails; another, to include accessory enzymes in the cocktails to increase yields by reducing the recalcitrant carbohydrate fraction remaining at the end of the process. To guide this second strategy, we have explored the chemical bond composition of different fractions of recalcitrant carbohydrates after enzymatic hydrolysis. Two lignocellulosic feedstocks of relevance for the biofuels industry have been analyzed, corn stover and sugarcane straw. On comparing the composition of chemical bonds of the starting pretreated material with samples after standard and forced hydrolysis (with enzyme overdosing), we obtained similar sugar and chemical bond composition. This suggests that the current enzymatic cocktails bear the set of enzymes needed to hydrolyze these feedstocks. From o...
Books in Soils, Plants, and the Environment, 2016
Plant and Cell Physiology, 2016
Cyt, cytochrome; Cox, cytochrome c oxidase; E m , midpoint redox potential; Em,7, midpoint redox ... more Cyt, cytochrome; Cox, cytochrome c oxidase; E m , midpoint redox potential; Em,7, midpoint redox potential at pH 7; GFP, green fluorescent protein; k bim , second-order rate constant; k inf , second-order rate constant extrapolated to infinite ionic strength; k obs , observed pseudo-first-order rate constant; ORF, open reading frame; Pc, plastocyanin; pI, isoelectric point; PSI, photosystem I.
Biochemical and Biophysical Research Communications, 2006
Two synthetic genes coding for human and Arabidopsis cytochrome c, respectively, have been design... more Two synthetic genes coding for human and Arabidopsis cytochrome c, respectively, have been designed and constructed, and the recombinant proteins have been over-expressed in Escherichia coli cells. Thus a comparative analysis of the two heme proteins, including horse cytochrome c as a reference, has been performed. In addition to their physico-chemical properties, the redox behavior of the three proteins has been analyzed by following the kinetics of both their reduction by flavin semiquinones (lumiflavin, riboflavin, and FMN) and oxidation by cytochrome c oxidase. The resulting data indicate that the accessibility and electrostatic charge of the active site do not differ in a significant way among the three proteins, but human cytochrome c exhibits some intriguing differences when interacting with cytochrome c oxidase that could be related to the amino acid changes underwent by the latter along evolution.
J Biol Chem, 2000
Positively charged plastocyanin from Anabaena sp. PCC 7119 was investigated by site-directed muta... more Positively charged plastocyanin from Anabaena sp. PCC 7119 was investigated by site-directed mutagenesis. The reactivity of its mutants toward photosystem I was analyzed by laser flash spectroscopy. Replacement of arginine at position 88, which is adjacent to the copper ligand His-87, by glutamine and, in particular, by glutamate makes plastocyanin reduce its availability for transferring electrons to photosystem I. Such a residue in the copper protein thus appears to be isofunctional with Arg-64 (which is close to the heme group) in cytochrome c 6 from Anabaena (