Peroxiredoxins from the Prx1 subfamily (Prx) are highly regulated multifunctional proteins involved in oxidative stress response, redox signaling and cell protection. Prx is a homodimer that associates into a decamer. The monomer C-terminus plays intricate roles in Prx catalytic functions, decamer stability and interaction with its redox partner, the small reductase sulfiredoxin (Srx), that regulates the switching between Prx cellular functions. As only static structures of covalent Prx-Srx complexes have been reported, whether Srx binding dissociates the decameric assembly and how Prx subunit flexibility impacts complex formation are unknown. Here, we assessed the non-covalent interaction mechanism and dynamics in the solution of Saccharomyces cerevisiae Srx with the ten subunits of Prx Tsa1 at the decamer level via a combination of multiscale biophysical approaches including native mass spectrometry. We show that the ten subunits of the decamer can be saturated by ten Srx molecules and that the Tsa1 decamer in complex with Srx does not dissociate in solution. Furthermore, the binding events of atomic force microscopy (AFM) tip-grafted Srx molecules to Tsa1 individual subunits were relevant to the interactions between free molecules in solution. Combined with protein engineering and rapid kinetics, the observation of peculiar AFM force-distance signatures revealed that Tsa1 C-terminus flexibility controls Tsa1/Srx two-step binding and dynamics and determines the force-induced dissociation of Srx from each subunit of the decameric complex in a sequential or concerted mode. This combined approach from the solution to the single-molecule level offers promising prospects for understanding oligomeric protein interactions with their partners.

To know the genetic situation of the Pampa Rocha, Celta, Bizaro Portuguese, Duroc, Iberian Extremeno and Iberian Andalusian porcine populations. their genetic structure and population dynamics were studied on the IGF2 and MC4R genes, which determine meat characteristics and quality. The degree of genetic variability (He = 0.2511 in Pampa Rocha; 0.0278 in Celta; 0,1453 in Bizaro Portuguese; 0.3719 in Duroc; 0.0764 in Iberian Extremeno and 0.0384 in Iberian Andalusian). genetic distance, and the presence or absence of consanguinity were studied. The Fis values were positive for the Duroc population (0.00426) indicating a very low inbreeding, the rest of the populations did not present consanguinity. Significant deviations (P <= 0.05) in the Hardy-Weinberg (HW) equilibrium were obtained for the IGF2 locus in Celta, Iberian Extreme no, and Iberian Andalusian populations with the G allele fixed, while the Bizaro Portuguese. Pampa Rocha, and Duroc populations presented polymorphism, the G allelic frequency was much higher than A allele, except in the Duroc breed (0.15). These findings could help breeders to increase the presence of the A allele for the improvement of muscle mass and reduction in the back-fat thickness in this breed. All the studied populations presented polymorphism for the MC4R locus with different frequencies for each allele. Furthermore, these results could allow developing strategies against anthropogenic activities that hinder the conservation of the biodiversity of these porcine breeds.

Objetivo. El análisis de marcadores de selección permite obtener datos de la vida evolutiva de una raza o línea y permite también evaluar la conveniencia o no de su uso en programas de mejora genética. Hemos evaluado SNPs en cuatro genes (IGF2, MC4R, PRKAG3 y PEPCK-C), que tienen importantes efectos fenotípicos, en cerdos de la raza Pampa Rocha, una raza criolla, y hemos comparado sus frecuencias alélicas con cerdos de diversas razas autóctonas y líneas de España y Portugal no sometidas a selección así como con jabalíes y cerdos de la raza Piétrain. Materiales y métodos. Los SNPs fueron analizados mediante diversa técnicas de RT-PCR. Resultados. Los resultados de los análisis muestran una similitud de frecuencias alélicas entre los cerdos de la raza Pampa Rocha y los cerdos autóctonos de la península ibérica sobre todo en el gen IGF2 y, en menor medida en el gen PEPCK-C. Sin embargo difieren considerablemente en el caso del marcador MC4R y, también en menor medida, en PRKAG3. En el trabajo se discute el uso potencial de los resultados obtenidos para orientar la selección genética de cerdos de la raza Pampa Rocha. Conclusiones. Nuestros resultados demuestran la peculiaridad de la raza Pampa Rocha con respecto a los marcadores estudiados.

Objective. The analysis of selection markers allows to obtain information about the evolutive story of a particular breed or line and allows also to evaluate the usefulness of those markers for breeding programs. We have analyzed SNPs in four genes of the creole pig breed Pampa Rocha and we have compared their allelic frequencies with the allelic frequencies of diverse autochthonous breeds of Spain and Portugal and also with Piétrain pigs and wild boars. Materials and methods. The SNPs were analyzed using diverse RT-PCR methods. Results. The results of the analysis show that Pampa Rocha pigs have similar allelic frequencies with the autochthonous breeds of Spain and Portugal especially in the case of IGF2 and also, but not so coincident, in the case of PEPCK-C. However, they differ considerably for MC4R, and also, but in a lower extent, for PRKAG3. We discuss in this work the usefulness of our results for breeding of Pampa Rocha pigs. Conclusions. Our results demonstrate the peculiarity of the Pampa Rocha breed regarding the markers studied

Cytosolic phosphoenolpyruvate carboxykinase, PCK1, is one of the main regulatory enzymes of gluconeogenesis and glyceroneogenesis. The substitution of a single amino acid (Met139Leu) in PCK1 as a consequence of a single nucleotide polymorphism (SNP), c.A2456C, is associated in the pig to a negative phenotype characterized by reduced intramuscular fat content, enhanced backfat thickness and lower meat quality. The p.139L enzyme shows reduced kcat values in the glyceroneogenic direction and enhanced ones in the anaplerotic direction. Accordingly, the expression of the p.139L isoform results in about 30% lower glucose and 9% lower lipid production in cell cultures. Moreover, the ability of this isoform to be acetylated is also compromised, what would increase its susceptibility to be degraded in vivo by the ubiquitin-proteasome system. The high frequency of the c.2456C allele in modern pig breeds implies that the benefits of including c.A2456C SNP in selection programs could be considerable.

The cytosolic form of phosphoenolpyruvate carboxykinase (PCK1) plays a regulatory role in gluconeogenesis and glyceroneogenesis. The role of the mitochondrial isoform (PCK2) remains unclear. We report the partial purification and kinetic and functional characterization of human PCK2. Kinetic properties of the enzyme are very similar to those of the cytosolic enzyme. PCK2 has an absolute requirement for Mn2+ ions for activity; Mg2+ ions reduce the Km for Mn2+ by about 60 fold. Its specificity constant is 100 fold larger for oxaloacetate than for phosphoenolpyruvate suggesting that oxaloacetate phosphorylation is the favored reaction in vivo. The enzyme possesses weak pyruvate kinase-like activity (kcat=2.7s−1). When overexpressed in HEK293T cells it enhances strongly glucose and lipid production showing that it can play, as the cytosolic isoenzyme, an active role in glyceroneogenesis and gluconeogenesis.

There exist two isoforms of cytosolic phosphoenolpyruvate carboxykinase (PEPCK-C) in pig populations that differ in a single amino acid (Met139Leu). The isoenzymes have different kinetic properties, affecting more strongly the Km and Vmax of nucleotides. They are associated to different phenotypes modifying traits of considerable economic interest. In this work we use inhibitors of phosphoenolpyruvate carboxykinase activity to search for further differences between these isoenzymes. On the one hand we have used the well-known inhibitor 3-mercaptopicolinic acid. Its inhibition patterns were the same for both isoenzymes: a three-fold decrease of the Ki values for GTP in 139Met and 139Leu (273 and 873 μM, respectively). On the other hand, through screening of a chemical library we have found two novel compounds with inhibitory effects of a similar magnitude to that of 3-mercaptopicolinic acid but with less solubility and specificity. One of these novel compounds, (N'1-({5-[1-methyl-5-(trifluoromethyl)-1H-pyrazol-3-yl]-2-thienyl}methylidene)-2,4-dichlorobenzene-1-carbohydrazide), exhibited significantly different inhibitory effects on either isoenzyme: it enhanced threefold the apparent Km value for GTP in 139Met, whereas in 139Leu, it reduced it from 99 to 69 μM. The finding of those significant differences in the binding of GTP reinforces the hypothesis that the Met139Leu substitution affects strongly the nucleotide binding site of PEPCK-C.