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The thermodynamic properties and the electron transfer between PFOR and either native or mutated FdI are investigated. The remarkable flexibility fo the PFOR-FdI system supports the idea that the specificity of the physiological complex has probably sacrificed to improve the turnover rate and thus the efficiency.

The Pyruvate-ferredoxin oxidoreductase of the bacterium Desulfovibrio africanus, the production of the recombinant enzyme in Escherichia coli and the effect of carboxy-terminal deletions on its stability was analyzed. Results of the study revealed a stable recombinant enzyme toward oxygen for several days. These proves that the recombinant enzyme behaves like the native D. africanus enzyme.

Studies on disulfide bond-dependent reversible mechanism observed in the Desulfovibrio species to protect one of the key enzymes, pyruvate-ferredoxin oxidoreductase (PFOR) against oxidative stress are reported.

Oxidative decarboxylation of pyruvate to form acetyl?coenzyme A, a crucial step in many metabolic pathways, is carried out in most aerobic organisms by the multienzyme complex pyruvate dehydrogenase. In most anaerobes, the same reaction is usually catalyzed by a single enzyme, pyruvate:ferredoxin oxidoreductase (PFOR). Thus, PFOR is a potential target for drug design against certain anaerobic pathogens. Here, we report the crystal structures of the homodimeric Desulfovibrio africanus PFOR (data to 2.3 Å resolution), and of its complex with pyruvate (3.0 Å resolution). The structures show that each subunit consists of seven domains, one of which affords protection against oxygen. The thiamin pyrophosphate (TPP) cofactor and the three [4Fe?4S] clusters are suitably arranged to provide a plausible electron transfer pathway. In addition, the PFOR?pyruvate complex structure shows the noncovalent fixation of the substrate before the catalytic reaction. [ABSTRACT FROM AUTHOR]

Thioredoxins are ubiquitous key antioxidant enzymes which play an essential role in cell defense against oxidative stress. They maintain the redox homeostasis owing to the regulation of thiol-disulfide exchange. In the present paper, we report the full resonance assignments of H, C and N atoms for the reduced and oxidized forms of Desulfovibrio vulgaris Hildenborough thioredoxin 1 (Trx1). 2D and 3D heteronuclear NMR experiments were performed using uniformly N-, C-labelled Trx1. Chemical shifts of 97% of the backbone and 90% of the side chain atoms were obtained for the oxidized and reduced form (BMRB deposits with accession number 17299 and 17300, respectively). [ABSTRACT FROM AUTHOR]

Based on sequence homology, desulfothioredoxin (DTrx) from Desulfovibrio vulgaris Hildenborough has been identified as a new member of the thioredoxin superfamily. Desulfothioredoxin (104 amino acids) contains a particular active site consensus sequence, CPHC probably correlated to the anaerobic metabolism of these bacteria. We report the full H, C and N resonance assignments of the reduced and the oxidized form of desulfothioredoxin (DTrx). 2D and 3D heteronuclear NMR experiments were performed using uniformly N-, C-labelled DTrx. More than 98% backbone and 96% side-chain H, C and N resonance assignments were obtained. (BMRB deposits with accession number 16712 and 16713). [ABSTRACT FROM AUTHOR]

Importance: Type 4 filaments (T4F) are nanomachines ubiquitous in prokaryotes, centered on filamentous polymers of type 4 pilins. T4F are exceptionally versatile and widespread virulence factors in bacterial pathogens. The mechanisms of filament assembly and the many functions they facilitate remain poorly understood because of the complexity of T4F machineries. This hinders the development of anti-T4F drugs. The significance of our research lies in characterizing the simplest known T4F-the Com pilus that mediates DNA uptake in competent monoderm bacteria-and showing that four protein components universally conserved in T4F are sufficient for filament assembly. The Com pilus becomes a model for elucidating the mechanisms of T4F assembly., Competing Interests: The authors declare no conflict of interest.

The ability to respire sulfate linked to lactate oxidation is a key metabolic signature of the Desulfovibrio genus. Lactate oxidation by these incomplete oxidizers generates reductants through lactate dehydrogenase (LDH) and pyruvate-ferredoxin oxidoreductase (PFOR), with the latter catalyzing pyruvate conversion into acetyl-CoA. Acetyl-CoA is the source of substrate-level phosphorylation through the production of ATP. Here, we show that these crucial steps are performed by enzymes encoded by a nonacistronic transcriptional unit named now as operon luo (for lactate utilization operon). Using a combination of genetic and biochemical techniques, we assigned a physiological role to the operon genes DVU3027-28 and DVU3032-33. The growth of mutant Δ26-28 was highly disrupted on D-lactate, whereas the growth of mutant Δ32-33 was slower on L-lactate, which could be related to a decrease in the activity of D-lactate or L-lactate oxidase in the corresponding mutants. The DVU3027-28 and DVU3032-33 genes thus encode functional D-LDH and L-LDH enzymes, respectively. Scanning of the genome for lactate utilization revealed several lactate permease and dehydrogenase homologs. However, transcriptional compensation was not observed in any of the mutants except for lactate permease. Although there is a high degree of redundancy for lactate oxidase, it is not functionally efficient in LDH mutants. This result could be related to the identification of several operon enzymes, including LDHs, in the PFOR activity bands, suggesting the occurrence of a lactate-oxidizing supermolecular structure that can optimize the performance of lactate utilization in Desulfovibrio species.