Biochemical and mutational studies of allantoinase from Bacillus licheniformis CECT 20T.

Allantoinases (allantoin amidohydrolase, E.C. 3.5.2.5) catalyze the hydrolysis of the amide bond of allantoin to form allantoic acid, in those organisms where allantoin is not the final product of uric acid degradation. Despite their importance in the purine catabolic pathway, sequences of microbial allantoinases with proven activity are scarce, and only the enzyme from Escherichia coli (AllEco) has been studied in detail in the genomic era. In this work, we report the cloning, purification and characterization of the recombinant allantoinase from Bacillus licheniformis CECT 20T (AllBali). The enzyme was a homotetramer with an apparent Tm of 62 ± 1 °C. Optimal parameters for the enzyme activity were pH 7.5 and 50 °C, showing apparent Km and kcat values of 17.7 ± 2.7 mM and 24.4 ± 1.5 s−1, respectively. Co2+ proved to be the most effective cofactor, inverting the enantioselectivity of AllBali when compared to that previously reported for other allantoinases. The common ability of different cyclic amidohydrolases to hydrolyze distinct substrates to the natural one also proved true for AllBali. The enzyme was able to hydrolyze hydantoin, dihydrouracil and 5-ethyl-hydantoin, although at relative rates 3–4 orders of magnitude lower than with allantoin. Mutagenesis experiments suggest that S292 is likely implicated in the binding of the allantoin ring through the carbonyl group of the polypeptide main chain, which is the common mechanism observed in other members of the amidohydrolase family. In addition, our results suggest an allosteric effect of H2O2 toward allantoinase.pre-print829 K

Biochemical and Mutational Studies of the Bacillus cereus CECT 5050T Formamidase Support the Existence of a C-E-E-K Tetrad in Several Members of the Nitrilase Superfamily.

Formamidases (EC 3.5.1.49) are poorly characterized proteins. In spite of this scarce knowledge, ammonia has been described as playing a central role in the pathogenesis of human pathogens such as Helicobacter pylori, for which formamidase has been shown to participate in the nitrogen metabolic pathway. Sequence analysis has revealed that at least two different groups of formamidases are classified as EC 3.5.1.49: on the one hand, the derivatives of the FmdA-AmdA superfamily, which are the best studied to date, and on the other hand, the derivatives of Helicobacter pylori AmiF. Here we present the cloning, purification, and characterization of a recombinant formamidase from Bacillus cereus CECT 5050T (BceAmiF), the second member of the AmiF subfamily to be characterized, showing new features of the enzyme further supporting its relationship with aliphatic amidases. We also present homology modeling-based mutational studies confirming the importance of the Glu140 and Tyr191 residues in the enzymatic activities of the AmiF family. Moreover, we can conclude that a second glutamate residue is critical in several members of the nitrilase superfamily, meaning that what has consistently been identified as a C-E-K triad is in fact a C-E-E-K tetrad.pre-print615 K

Enzymatic dynamic kinetic resolution of racemic N-formyl- and N-carbamoyl-amino acids using immobilized L-N-carbamoylase and N-succinyl-amino acid racemase.

Taking advantage of the catalytic promiscuity of L-carbamoylase from Geobacillus stearothermophilus CECT43 (BsLcar) and N-succinyl-amino acid racemase from Geobacillus kaustophilus CECT4264 (GkNSAAR), we have evaluated the production of different optically pure L-α-amino acids starting from different racemic N-formyl- and N-carbamoyl-amino acids using a dynamic kinetic resolution approach. The enzymes were immobilized on two different solid supports, resulting in improved stability of the enzymes in terms of thermostability and storage when compared to the enzymes in solution. The bienzymatic system retained up to 80 % conversion efficiency after 20 weeks at 4 °C and up to 90 % after 1 week at 45 °C. The immobilization process also resulted in a great enhancement of the activity of BsLcar toward N-formyl-tryptophan, showing for the first time that substrate specificity of L-carbamoylases can be influenced by this approach. The system was effective for the biosynthesis of natural and unnatural L-amino acids (enantiomeric excess (e.e.) >99.5 %), such as L-methionine, L-alanine, L-tryptophan, L-homophenylalanine, L-aminobutyric acid, and L-norleucine, with a higher performance toward N-formyl-α-amino acid substrates. Biocatalyst reuse was studied, and after 10 reaction cycles, over 75 % activity remained.post-print1047 K

Biochemical and Mutational Characterization of N-Succinyl-Amino Acid Racemase from Geobacillus stearothermophilus CECT49.

N-Succinyl-amino acid racemase (NSAAR), long referred to as N-acyl- or N-acetyl-amino acid racemase, is an enolase superfamily member whose biotechnological potential was discovered decades ago, due to its use in the industrial dynamic kinetic resolution methodology first known as “Acylase Process”. In previous works, an extended and enhanced substrate spectrum of the NSAAR from Geobacillus kaustophilus CECT4264 toward different N-substituted amino acids was reported. In this work, we describe the cloning, purification, and characterization of the NSAAR from Geobacillus stearothermophilus CECT49 (GstNSAAR). The enzyme has been extensively characterized, showing a higher preference toward N-formyl-amino acids than to N-acetyl-amino acids, thus confirming that the use of the former substrates is more appropriate for a biotechnological application of the enzyme. The enzyme showed an apparent thermal denaturation midpoint of 77.0 ± 0.1 °C and an apparent molecular mass of 184 ± 5 kDa, suggesting a tetrameric species. Optimal parameters for the enzyme activity were pH 8.0 and 55–65 °C, with Co2+ as the most effective cofactor. Mutagenesis and binding experiments confirmed K166, D191, E216, D241, and K265 as key residues in the activity of GstNSAAR, but not indispensable for substrate binding.pre-print784 K

An allosteric switch between the activation loop and a c-terminal palindromic phosphomotif controls c-Src function.

Autophosphorylation controls the transition between discrete functional and conformational states in protein kinases, yet the structural and molecular determinants underlying this fundamental process remain unclear. Here we show that c-terminal Tyr 530 is a de facto c-Src autophosphorylation site with slow time-resolution kinetics and a strong intermolecular component. On the contrary, activation-loop Tyr 419 undergoes faster kinetics and a cis-to-trans phosphorylation switch that controls c-terminal Tyr 530 autophosphorylation, enzyme specificity, and strikingly, c-Src non-catalytic function as a substrate. In line with this, we visualize by X-ray crystallography a snapshot of Tyr 530 intermolecular autophosphorylation. In an asymmetric arrangement of both catalytic domains, a c-terminal palindromic phospho-motif flanking Tyr 530 on the substrate molecule engages the G-loop of the active kinase adopting a position ready for entry into the catalytic cleft. Perturbation of the phosphomotif accounts for c-Src dysfunction as indicated by viral and colorectal cancer (CRC)-associated c-terminal deleted variants.Weshow that c-terminal residues 531 to 536 are required for c-Src Tyr 530 autophosphorylation, and such a detrimental effect is caused by the substrate molecule inhibiting allosterically the active kinase. Our work reveals a crosstalk between the activation and c-terminal segments that control the allosteric interplay between substrateand enzyme-acting kinases during autophosphorylation.post-print5137 K

Effects of 12-week Aerobic Exercise on Arterial Stiffness, Inflammation, and Cardiorespiratory Fitness in Women with Systemic LUPUS Erythematosus: Non-Randomized Controlled Trial

This study assessed the effect of 12-week aerobic exercise on arterial stiffness (primary outcome), inflammation, oxidative stress, and cardiorespiratory fitness (secondary outcomes) in women with systemic lupus erythematosus (SLE). In a non-randomized clinical trial, 58 women with SLE were assigned to either aerobic exercise (n = 26) or usual care (n = 32). The intervention comprised 12 weeks of aerobic exercise (2 sessions X 75 min/week) between 40–75% of the individual’s heart rate reserve. At baseline and at week 12, arterial stiffness was assessed through pulse wave velocity (PWV), inflammatory (i.e., high-sensitivity C-reactive protein [hsCRP], tumor necrosis factor alpha [TFN- α], and inteleukin 6 [IL-6]) and oxidative stress (i.e., myeloperoxidase [MPO]) markers were obtained from blood samples, and cardiorespiratory fitness was assessed (Bruce test). There were no between-group differences in the changes in arterial stiffness (median PWV difference -0.034, 95% CI -0.42 to 0.36 m/s; p = 0.860) or hsCRP, TNF-α, IL-6, and MPO (all p > 0.05) at week 12. In comparison to the control group, the exercise group significantly increased cardiorespiratory fitness (median difference 2.26 minutes, 95% CI 0.98 to 3.55; p = 0.001). These results suggest that 12 weeks of progressive treadmill aerobic exercise increases cardiorespiratory fitness without exacerbating arterial stiffness, inflammation, or oxidative stress in women with SLE.This work was supported by Fundación para la Investigación Biosanitaria de Andalucía Oriental (grant number: PI-0525-2016) and the Ilustre Colegio Oficial de Médicos de Granada (Premios de Investigación 2017). BG-C was supported by the Spanish Ministry of Education (FPU15/00002)

Physical Fitness and Body Composition in Women with Systemic Lupus Erythematosus

Background and objectives: Higher physical fitness is associated with a more favorable weight and body composition in the general population, although this association has not been studied in patients with systemic lupus erythematosus (SLE). The aim of the present study was to examine the association of different components of physical fitness with body composition in women with SLE with mild disease activity. Materials and Methods: This cross-sectional study included 77 women with SLE (43.2 ± 13.8 years old) and clinical stability during the previous 6 months. Body composition (including body mass index (BMI), fat mass index (FMI), waist circumference, waist-to-height ratio and waist-to-hip ratio) was assessed using a stadiometer, an anthropometric tape, and a bioimpedance device. Physical fitness included cardiorespiratory fitness (Siconolfi step test and 6 min walk test), muscular strength (handgrip strength test as upper body measure and 30 s chair stand as lower body measure), and flexibility (back-scratch test). Participants with a fitness level equal or above the median of the study sample were categorized as “fit” and those below the median were categorized as “unfit”. Linear regression assessed the association of physical fitness with body composition parameters. Results: Cardiorespiratory fitness and upper body muscular strength were negatively associated with BMI, FMI, waist circumference, and waistto- height ratio (all, p < 0.05). Lower body muscular strength and flexibility were negatively related to FMI, waist circumference, waist-to-height ratio, and waist-to-hip ratio (all, p < 0.05). These relationships were still significant after controlling for age, disease duration, accrual damage, and SLE activity. Overall, fit patients presented significantly lower values in all body composition parameters compared to unfit patients (all, p < 0.05). Conclusions: The main findings of the present study suggest that physical fitness is inversely associated with body composition in women with SLE. Given the cross-sectional nature of this study, future clinical trials should study the causal pathways underlying these relationships.This work was supported by Consejería de Salud, Junta de Andalucía (grant number: PI-0525-2016) and by the Ilustre Colegio Oficial de Médicos de Granada (Premios de Investigación 2017). BGC was supported by the Spanish Ministry of Education (FPU15/00002)

Estudio meteorológico del episodio tormentoso y precipitaciones torrenciales del 16 de agosto de 2010 en Aguilar de la Frontera (Córdoba)

Esta nota técnica, elaborada por un grupo de profesionales de AEMET, tiene como fin primordial poner de manifiesto las características meteorológicas fundamentales del episodio tormentoso torrencial que tuvo lugar durante la tarde-noche del 16 de agosto de 2010 en la provincia de Córdoba, y que afectó especialmente a las localidades de Aguilar de la Frontera y Bujalance. Este trabajo sirve como marco de referencia de un tipo de situaciones al que se puede llegar mediante la coexistencia en una misma zona de determinados elementos meteorológicos que confieren una altísima peligrosidad a la situación atmosférica. Se trató de un episodio poco habitual por su magnitud, en la que el rasgo dominante fue la presencia local y simultánea de varios ingredientes cruciales

Association of physical fitness components and health-related quality of life in women with systemic lupus erythematosus with mild disease activity

To study the association of different components of physical fitness [flexibility, muscle strength and cardiorespiratory fitness (CRF)] and a clustered fitness score with healthrelated quality of life (HRQoL) in women with systemic lupus erythematosus (SLE) and to analyze whether participants with high fitness level have better HRQoL. This cross-sectional study included 70 women with SLE (aged 42.5; SD 13.9 years). The back-scratch test assessed flexibility, the 30-sec chair stand and handgrip strength tests assessed muscle strength, and the 6-min walk test (n = 49) assessed CRF. HRQoL was assessed through the 36-item Short-Form Health Survey (SF-36). Our study suggests that muscle strength and CRF are positively associated with HRQoL, while flexibility showed contradictory results. These findings highlight the importance of maintaining adequate fitness levels in women with SLE.This work was supported by the Consejería de Salud, Junta de Andalucía (grant number: PI-0525-2016) and the Ilustre Colegio Oficial de Médicos de Granada (Premios de Investigación 2017). BG-C was supported by the Spanish Ministry of Education (FPU15/00002)