An Interaction between the Walker A and D-loop Motifs Is Critical to ATP Hydrolysis and Cooperativity in Bacteriophage T4 Rad50

The ATP binding cassette (ABC) proteins make up a large superfamily with members coming from all kingdoms. The functional form of the ABC protein nucleotide binding domain (NBD) is dimeric with ATP binding sites shared between subunits. The NBD is defined by six motifs: the Walker A, Q-loop, Signature, Walker-B, D-loop, and H-loop. The D-loop contains a conserved aspartate whose function is not clear but has been proposed to be involved in cross-talk between ATP binding sites. Structures of various ABC proteins suggest an interaction between the D-loop aspartate and an asparagine residue located in Walker A loop of the opposing subunit. Here, we evaluate the functional role of the D-loop using a bacteriophage T4 ABC protein, Rad50 (gp46). Mutation of either the D-loop aspartate or the Walker A asparagine results in dramatic reductions in ATP affinity, hydrolysis rate, and cooperativity. The mutant proteins bind Mre11 (gp47) and DNA normally, but no longer support the ATP-dependent nuclease activities of Mre11. We propose that the D-loop aspartate functions to stabilize the Walker A asparagine in a position favorable for catalysis. We find that the asparagine is crucially important to the mechanism of ATP hydrolysis by increasing the affinity for ATP and positioning the γ-phosphate of ATP for catalysis. Additionally, we propose that the asparagine acts as a γ-phosphate sensor and, through its interaction with the conserved D-loop aspartate, transmits conformational changes across the dimer interface to the second ATP binding site

Lack of Preventive Health Behaviors in the Early Forties: The Role of Earlier Trajectories of Cigarette Smoking From Adolescence to Adulthood

Objective: To study the degree to which individuals in different trajectories of cigarette smoking from adolescence to the early forties are similar or different in terms of lack of preventive health behaviors (e.g., underuse of preventive health services, unhealthy eating habits) in early midlife. Methods: Participants came from a community-based random sample of residents in two upstate New York counties (N = 548). Data were collected from adolescence to early midlife (mean age = 43 years, standard deviation [SD] = 2.8) at seven time points. Using growth mixture modeling, we statistically identified the number of smoking trajectories. Logistic regression analysis was used to study the relationship between the probabilities of participants\u27 smoking trajectory group membership and lack of preventive behaviors in early midlife. Results: Five trajectory groups of cigarette smokers were identified. With controls, as compared with the nonsmoker trajectory group, higher probabilities of belonging to the heavy/continuous smoker trajectory group and the late starter trajectory groups were significantly associated with a higher likelihood of lack of preventive health behaviors (adjusted odds ratio [AOR] = 3.49 and 4.02 respectively). In addition, as compared to the quitter/decreaser trajectory group, higher probabilities of belonging to the heavy/continuous smoker trajectory group and the late starter trajectory group were also significantly associated with a higher likelihood of lack of preventive health behaviors (AOR = 3.51 and 4.04 respectively). Conclusions: Intervention programs may consider focusing on heavy/continuous smokers and late starters in programs designed to promote adequate use of preventive health services and healthy general lifestyles in early midlife

Compulsive Buying and Quality of Life: An Estimate of the Monetary Cost of Compulsive Buying Among Adults in Early Midlife

The aims of this study were to examine the associations between compulsive buying and quality of life and to estimate the monetary cost of compulsive buying for a cohort of men and women at mean age 43. Participants came from a community-based random sample of residents in two New York counties (N=548). The participants were followed from adolescence to early midlife. The mean age of participants at the most recent interview was 43.0 (SD=2.8). Fifty five percent of the participants were females. Over 90% of the participants were white. Linear regression analyses showed that compulsive buying was significantly associated with quality of life, despite controlling for relevant demographic and psychosocial factors. The estimated monetary cost of compulsive buying for this cohort was significant. The fact that the monetary cost of CB is not trivial suggests that individuals are both consciously and unconsciously plagued by their CB. The findings are important for interventionists and clinicians for cost-effective intervention and treatment programs

Psychosocial Factors Related to the Intergenerational Transmission of Externalizing Behaviors in Early Midlife

Background: To study the intergenerational transmission of externalizing behaviors. Methods: Participants came from a community-based random sample of residents in two upstate New York counties (N = 548). Data were collected from mothers at mean age 40 and from their children from adolescence (mean age = 14, SD = 2.8) to early midlife (mean age = 43, SD = 2.8) at seven time points. Structural equation modeling (SEM) was used to study the psychosocial factors as related to externalizing behaviors in early midlife. Results: First, maternal externalizing behaviors were indirectly associated with the offspring\u27s externalizing behaviors through the offspring\u27s substance use in adolescence, the offspring\u27s partner\u27s smoking patterns, and the offspring\u27s marital conflict. Second, maternal cigarette smoking was indirectly associated with the offspring\u27s externalizing behaviors through the offspring\u27s substance use in adolescence, the offspring\u27s partner\u27s cigarette smoking, and the offspring\u27s marital conflict. Third, maternal marital conflict had an indirect effect on the offspring\u27s externalizing behaviors, mediated by offspring marital conflict. Conclusions: The finding that externalizing behaviors can be transmitted from parent to child informs the need for family-based interventions that are appropriate to adolescents

Oxidizing Side of the Cyanobacterial Photosystem I

Photosystem I (PSI) interacts with plastocyanin or cytochrome c 6 on the luminal side. To identify sites of interaction between plastocyanin/cytochromec 6 and the PSI core, site-directed mutations were generated in the luminal J loop of the PsaB protein fromSynechocystis sp. PCC 6803. The eight mutant strains differed in their photoautotrophic growth. Western blotting with subunit-specific antibodies indicated that the mutations affected the PSI level in the thylakoid membranes. PSI proteins could not be detected in the S600R/G601C/N602I, N609K/S610C/T611I, and M614I/G615C/W616A mutant membranes. The other mutant strains contained different levels of PSI proteins. Among the mutant strains that contained PSI proteins, the H595C/L596I, Q627H/L628C/I629S, and N638C/N639S mutants showed similar levels of PSI-mediated electron transfer activity when either cytochrome c 6 or an artificial electron donor was used. In contrast, cytochromec 6 could not function as an electron donor to the W622C/A623R mutant, even though the PSI activity mediated by an artificial electron donor was detected in this mutant. Thus, the W622C/A623R mutation affected the interaction of the PSI complex with cytochrome c 6. Biotin-maleimide modification of the mutant PSI complexes indicated that His-595, Trp-622, Leu-628, Tyr-632, and Asn-638 in wild-type PsaB may be exposed on the surface of the PSI complex. The results presented here demonstrate the role of an extramembrane loop of a PSI core protein in the interaction with soluble electron donor proteins

Evidence for tidal interaction and merger as the origin of galaxy morphology evolution in compact groups

We present the results of a morphological study based on NIR images of 25 galaxies, with different levels of nuclear activity, in 8 Compact Groups of Galaxies (CGs). We perform independently two different analysis: a isophotal study and a study of morphological asymmetries. The results yielded by the two analysis are highly consistent. For the first time, it is possible to show that deviations from pure ellipses are produced by inhomogeneous stellar mass distributions related to galaxy interactions and mergers. We find evidence of mass asymmetries in 74% of the galaxies in our sample. In 59% of these cases, the asymmetries come in pairs, and are consistent with tidal effects produced by the proximity of companion galaxies. The symmetric galaxies are generally small in size or mass, inactive, and have an early-type morphology. In 20% of the galaxies we find evidence for cannibalism. In 36% of the early-type galaxies the color gradient is positive (blue nucleus) or flat. Summing up these results, as much as 52% of the galaxies in our sample could show evidence of an on going or past mergers. Our observations suggest that galaxies in CGs merge more frequently under ``dry'' conditions. The high frequency of interacting and merging galaxies observed in our study is consistent with the bias of our sample towards CGs of type B, which represents the most active phase in the evolution of the groups. In these groups we also find a strong correlation between asymmetries and nuclear activity in early-type galaxies. This correlation allows us to identify tidal interactions and mergers as the cause of galaxy morphology transformation in CGs.[abridge]Comment: 64 pages, 35 figures. Accepted for publication in Ap

Transporte de aerosoles de origen desértico a diferente escala espacio-temporal. Relación con perturbaciones tropicales

Ponencia presentada en: XXX Jornadas Científicas de la AME y el IX Encuentro Hispano Luso de Meteorología celebrado en Zaragoza, del 5 al 7 de mayo de 2008

11β-HSD2 SUMOylation Modulates Cortisol-induced Mineralocorticoid Receptor Nuclear Translocation Independently of Effects on Transactivation

The enzyme 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2) has an essential role in aldosterone target tissues, conferring aldosterone selectivity for the mineralocorticoid receptor (MR) by converting 11β-hydroxyglucocorticoids to inactive 11-ketosteroids. Congenital deficiency of 11β-HSD2 causes a form of salt-sensitive hypertension known as the syndrome of apparent mineralocorticoid excess. The disease phenotype, which ranges from mild to severe, correlates well with reduction in enzyme activity. Furthermore, polymorphisms in the 11β-HSD2 coding gene (HSD11B2) have been linked to high blood pressure and salt sensitivity, major cardiovascular risk factors. 11β-HSD2 expression is controlled by different factors such as cytokines, sex steroids, or vasopressin, but posttranslational modulation of its activity has not been explored. Analysis of 11β-HSD2 sequence revealed a consensus site for conjugation of small ubiquitin-related modifier (SUMO) peptide, a major posttranslational regulatory event in several cellular processes. Our results demonstrate that 11β-HSD2 is SUMOylated at lysine 266. Non-SUMOylatable mutant K266R showed slightly higher substrate affinity and decreased Vmax, but no effects on protein stability or subcellular localization. Despite mild changes in enzyme activity, mutant K266R was unable to prevent cortisol-dependent MR nuclear translocation. The same effect was achieved by coexpression of wild-type 11β-HSD2 with sentrin-specific protease 1, a protease that catalyzes SUMO deconjugation. In the presence of 11β-HSD2-K266R, increased nuclear MR localization did not correlate with increased response to cortisol or increased recruitment of transcriptional coregulators. Taken together, our data suggests that SUMOylation of 11β-HSD2 at residue K266 modulates cortisol-mediated MR nuclear translocation independently of effects on transactivation