Emerging nitrogen-fixing cyanobacteria for sustainable cotton cultivation.

Amid growing environmental concerns and the imperative for sustainable agricultural practices, this study examines the potential of nitrogen-fixing cyanobacteria as biofertilizers, particularly in cotton cultivation. The reliance on synthetic nitrogen fertilizers (SNFs), prevalent in modern agriculture, poses significant environmental challenges, including greenhouse gas emissions and water system contamination. This research aims to shift this paradigm by exploring the capacity of cyanobacteria as a natural and sustainable alternative.

Phylogenetic and functional analysis of cyanobacterial Cytochrome -like proteins.

All known photosynthetic cyanobacteria carry a cytochrome protein that acts transferring electrons from cytochrome complex to photosystem I, in photosynthesis, or cytochrome oxidase, in respiration. In most of the cyanobacteria, at least one homologue to cytochrome is found, the so-called cytochrome or cytochrome . However, the function of these cytochrome -like proteins is still unknown.

Plant Growth-Promoting Rhizobacteria Improve Rice Response to Climate Change Conditions.

Rice is one of the most important crops in the world and is considered a strategic crop for food security. Furthermore, the excessive use of chemical fertilizers to obtain high yields causes environmental problems. A sustainable alternative includes taking advantage of beneficial bacteria that promote plant growth.

Symbiosis between cyanobacteria and plants: from molecular studies to agronomic applications.

Nitrogen-fixing cyanobacteria from the order Nostocales are able to establish symbiotic relationships with diverse plant species. They are promiscuous symbionts, as the same strain of cyanobacterium is able to form symbiotic biological nitrogen-fixing relationships with different plants species. This review will focus on the different types of cyanobacterial-plant associations, both endophytic and epiphytic, and provide insights from a structural viewpoint, as well as our current understanding of the mechanisms involved in the symbiotic crosstalk.

Quantitative Proteomics at Early Stages of the Symbiotic Interaction Between Oryza sativa and Nostoc punctiforme Reveals Novel Proteins Involved in the Symbiotic Crosstalk.

Symbiosis between cyanobacteria and plants is considered pivotal for biological nitrogen deposition in terrestrial ecosystems. Despite extensive knowledge of the ecology of plant-cyanobacterium symbioses, little is known about the molecular mechanisms involved in recognition between partners. Here, we conducted a quantitative sequential window acquisition of all theoretical fragment ion spectra mass spectrometry pipeline to analyze protein changes in Oryza sativa and Nostoc punctiforme during early events of symbiosis.

Endophytic Colonization of Rice ( L.) by the Symbiotic Strain PCC 73102.

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 to promote a long-term stable endophytic association with rice.

Cytochrome c is the main respiratory and photosynthetic soluble electron donor in heterocysts of the cyanobacterium Anabaena sp. PCC 7120.

Cytochrome c is a soluble electron carrier, present in all known cyanobacteria, that has been replaced by plastocyanin in plants. Despite their high structural differences, both proteins have been reported to be isofunctional in cyanobacteria and green algae, acting as alternative electron carriers from the cytochrome b-f complex to photosystem I or terminal oxidases. We have investigated the subcellular localization of both cytochrome c and plastocyanin in the heterocyst-forming cyanobacterium Anabaena sp.

Management of enzyme diversity in high-performance cellulolytic cocktails.

Background: 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.

Cyt c6-3: A New Isoform of Photosynthetic Cyt c6 Exclusive to Heterocyst-Forming Cyanobacteria.

All known cyanobacteria contain Cyt c6, a small soluble electron carrier protein whose main function is to transfer electrons from the Cyt b6f complex to PSI, although it is also involved in respiration. We have previously described a second isoform of this protein, the Cyt c6-like, whose function remains unknown. Here we describe a third isoform of Cyt c6 (here called Cytc6-3), which is only found in heterocyst-forming filamentous cyanobacteria.

Recalcitrant carbohydrates after enzymatic hydrolysis of pretreated lignocellulosic biomass.

Background: 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.

Results: Two lignocellulosic feedstocks of relevance for the biofuels industry have been analyzed, corn stover and sugarcane straw.

Interaction of photosystem I from Phaeodactylum tricornutum with plastocyanins as compared with its native cytochrome c6: Reunion with a lost donor.

In the Phaeodactylum tricornutum alga, as in most diatoms, cytochrome c6 is the only electron donor to photosystem I, and thus they lack plastocyanin as an alternative electron carrier. We have investigated, by using laser-flash absorption spectroscopy, the electron transfer to Phaeodactylum photosystem I from plastocyanins from cyanobacteria, green algae and plants, as compared with its own cytochrome c6. Diatom photosystem I is able to effectively react with eukaryotic acidic plastocyanins, although with less efficiency than with Phaeodactylum cytochrome c6.

Photosystem I reduction in diatoms: as complex as the green lineage systems but less efficient.

Diatoms occupy a key branch in the evolutionary tree of oxygen-evolving photosynthetic organisms. Here, the electron transfer reaction mechanism from cytochrome c₆ to photosystem I from the diatom Phaeodactylum tricornutum has been analyzed by laser-flash absorption spectroscopy. Kinetic traces of photosystem I reduction fit to biphasic curves, the analysis of the observed rate constants indicating that electron transfer occurs in a cytochrome c₆/photosystem I transient complex, which undergoes a reorganization process from the initial encounter complex to the optimized final configuration.

Cytochrome c6-like protein as a putative donor of electrons to photosystem I in the cyanobacterium Nostoc sp. PCC 7119.

Most organisms performing oxygenic photosynthesis contain either cytochrome c(6) or plastocyanin, or both, to transfer electrons from cytochrome b(6)-f to photosystem I. Even though plastocyanin has superseded cytochrome c(6) along evolution, plants contain a modified cytochrome c(6), the so called cytochrome c(6A), whose function still remains unknown. In this article, we describe a second cytochrome c(6) (the so called cytochrome c(6)-like protein), which is found in some cyanobacteria but is phylogenetically more related to plant cytochrome c(6A) than to cyanobacterial cytochrome c(6).

A novel alpha-amylase from the cyanobacterium Nostoc sp. PCC 7119.

Little information is yet available on the alpha-amylases of cyanobacteria. Here, the presence of an alpha-amylase in the cyanobacterium Nostoc sp. PCC 7119 is first demonstrated.

Gated electron transfer of cytochrome c6 at biomimetic interfaces: a time-resolved SERR study.

The electron shuttle heme protein Cyt-c(6) from the photosynthetic cyanobacterium Nostoc sp. PCC 7119 was immobilized on nanostructured Ag electrodes coated with SAMs that mimic different possible interactions with its natural reaction partner PSI. The structure, redox potential, and electron-transfer dynamics of the SAM-Cyt-c(6) complexes were investigated by TR-SERR spectroelectrochemistry.

Detoxification of superoxide without production of H2O2: antioxidant activity of superoxide reductase complexed with ferrocyanide.

The superoxide radical O(2)(-.) is a toxic by-product of oxygen metabolism. Two O(2)(-.

A comparative kinetic analysis of the reactivity of plant, horse, and human respiratory cytochrome c towards cytochrome c oxidase.

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.

A comparative structural and functional analysis of cyanobacterial plastocyanin and cytochrome c (6) as alternative electron donors to Photosystem I.

Plastocyanin and cytochrome c (6) are two soluble metalloproteins that act as alternative electron carriers between the membrane-embedded complexes cytochromes b (6) f and Photosystem I. Despite plastocyanin and cytochrome c (6) differing in the nature of their redox center (one is a copper protein, the other is a heme protein) and folding pattern (one is a beta-barrel, the other consists of alpha-helices), they are exchangeable in green algae and cyanobacteria. In fact, the two proteins share a number of structural similarities that allow them to interact with the same membrane complexes in a similar way.

Laser flash-induced kinetic analysis of cytochrome f oxidation by wild-type and mutant plastocyanin from the cyanobacterium Nostoc sp. PCC 7119.

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.

NMR analysis of the transient complex between membrane photosystem I and soluble cytochrome c6.

A structural analysis of the surface areas of cytochrome c(6), responsible for the transient interaction with photosystem I, was performed by NMR transverse relaxation-optimized spectroscopy. The hemeprotein was titrated by adding increasing amounts of the chlorophyllic photosystem, and the NMR spectra of the free and bound protein were analyzed in a comparative way. The NMR signals of cytochrome c(6) residues located at the hydrophobic and electrostatic patches, which both surround the heme cleft, were specifically modified by binding.

Structure of superoxide reductase bound to ferrocyanide and active site expansion upon X-ray-induced photo-reduction.

Some sulfate-reducing and microaerophilic bacteria rely on the enzyme superoxide reductase (SOR) to eliminate the toxic superoxide anion radical (O2*-). SOR catalyses the one-electron reduction of O2*- to hydrogen peroxide at a nonheme ferrous iron center. The structures of Desulfoarculus baarsii SOR (mutant E47A) alone and in complex with ferrocyanide were solved to 1.

Redox properties of Arabidopsis cytochrome c6 are independent of the loop extension specific to higher plants.

Cytochrome c6 (cytc6) 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 cytc6 proteins. However, homology modelling suggests this is not the case.

The interactions of cyanobacterial cytochrome c6 and cytochrome f, characterized by NMR.

During oxygenic photosynthesis, cytochrome c(6) shuttles electrons between the membrane-bound complexes cytochrome bf and photosystem I. Complex formation between Phormidium laminosum cytochrome f and cytochrome c(6) from both Anabaena sp. PCC 7119 and Synechococcus elongatus has been investigated by nuclear magnetic resonance spectroscopy.

A comparative structural and functional analysis of cytochrome cM cytochrome c6 and plastocyanin from the cyanobacterium Synechocystis sp. PCC 6803.

Cytochrome cM is a new c-class photosynthetic haem protein whose physiological role is still unknown. It has been proposed previously that cytochrome cM can replace cytochrome c6 and plastocyanin in transferring electrons between the two membrane complexes cytochrome b6-f and photosystem I in organisms growing under stress conditions. The experimental evidence herein provided allows us to discard such a hypothesis.