Regulation of cytochrome c oxidase by interaction of ATP at two binding sites, one on subunit VIa

Cytochrome c oxidase isolated from a wild-type yeast strain and a mutant in which the gene for subunit VIa had been disrupted were used to study the interaction of adenine nucleotides with the enzyme complex. At low ionic strength (25 mM potassium phosphate), in the absence of nucleotides, the cytochrome c oxidase activity of the mutant enzyme lacking subunit VIa was higher than that of the wild-type enzyme. Increasing concentrations of ATP, in the physiological range, enhanced the cytochrome c oxidase activity of the mutant much more than the activity of the wild-type strain, whereas ADP, in the same concentration range, had no significant effect on the activity of the cytochrome c oxidase of either strain. These results indicate an interaction of ATP with subunit VIa in the wild-type enzyme that prevents the stimulation of the activity observed in the mutant enzyme. The stimulation of the mutant enzyme implies the presence of a second ATP binding site on the enzyme. Quantitative titrations with the fluorescent adenine nucleotide analogues 2'(or 3')-O-(2,4,6-trinitrophenyl)adenosine 5'-triphosphate (TNP-ATP) and 2'(or 3')-O-(2,4,6-trinitrophenyl)adenosine 5'-diphosphate (TNP-ADP) confirmed the presence of two binding sites for adenine nucleotides per monomer of wild-type cytochrome c oxidase and one binding site per monomer of mutant enzyme. Covalent photolabeling of yeast cytochrome c oxidase with radioactive 2-azido-ATP further confirmed the presence of an ATP binding site on subunit VIa.(ABSTRACT TRUNCATED AT 250 WORDS)     

Nucleotide-dependent movement of the epsilon subunit between alpha and beta subunits in the Escherichia coli F1F0-type ATPase

Mutants of ECF1-ATPase were generated, containing cysteine residues in one or more of the following positions: alphaSer-411, betaGlu-381, and epsilonSer-108, after which disulfide bridges could be created by CuCl2 induced oxidation in high yield between alpha and epsilon, beta and epsilon, alpha and gamma, beta and gamma (endogenous Cys-87), and alpha and beta. All of these cross-links lead to inhibition of ATP hydrolysis activity. In the two double mutants, containing a cysteine in epsilonSer-108 along with either the DELSEED region of beta (Glu-381) or the homologous region in alpha (Ser-411), there was a clear nucleotide dependence of the cross-link formation with the epsilon subunit. In betaE381C/epsilonS108C the beta-epsilon cross-link was obtained preferentially when Mg2+ and ADP + Pi (addition of MgCl2 + ATP) was present, while the alpha-epsilon cross-link product was strongly favored in the alphaS411C/epsilonS108C mutant in the Mg2+ ATP state (addition of MgCl2 + 5'-adenylyl-beta,gamma-imidodiphosphate). In the triple mutant alphaS411C/betaE381C/epsilonS108C, the epsilon subunit bound to the beta subunit in Mg2+-ADP and to the alpha subunit in Mg2+-ATP, indicating a significant movement of this subunit. The gamma subunit cross-linked to the beta subunit in higher yield in Mg2+-ATP than in Mg2+-ADP, and when possible, i.e. in the triple mutant, always preferred the interaction with the beta over the alpha subunit.     

Emotion dysregulation in the intergenerational transmission of romantic relationship conflict.

The role of emotion dysregulation in the intergenerational transmission of romantic relationship conflict was examined using multimethod and multiagent prospective longitudinal data across 21 years for 190 men and their mothers and fathers. As predicted, an individual’s emotion dysregulation was a key mediator in the transmission of relationship conflict, along with poor parenting skills. Parents’ emotion dysregulation was directly related to their son’s emotion dysregulation, which was in turn associated with the son’s later relationship conflict. Additionally, parents’ emotion dysregulation was significantly related to their poor discipline skills, which were linked to the son’s emotion dysregulation and eventual relationship conflict. Findings highlight emotion dysregulation as a significant mechanism explaining the continuity of romantic relationship conflict across generations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Suicidal ideation and its recurrence in boys and men from early adolescence to early adulthood: An event history analysis.

Occurrence and recurrences of suicidal ideation (SI) were modeled among boys/men assessed annually from ages 12 to 29 years. Multiple-spell discrete-time event-history analyses permitted (a) determination of whether risk for SI escalates with prior experiences of SI (spell effects), while (b) accounting for changes in risk with time (period effects) and (c) controlling for vulnerability factors. Self-reported SI (presence/absence in past week), depressive symptoms, alcohol/substance use, antisocial behavior, and official arrest records were collected annually from 205 boys recruited on the basis of community risk for delinquency. Parents' self-reported psychopathology and SES were collected in childhood. Period effects supported decreasing risk for SI over time. Spell and time-varying 1-year lagged substance use and depressive symptoms independently predicted increased risk for SI. Models involving SI with intent were explored. Consistent with interpersonal psychological theory, risk for young men's SI increases with past experience of SI, even with key propensities controlled. However, risk also decays over time. Targeting conditions that confer risk for SI is essential. Preventing and delaying SI occurrence and recurrence may represent independent mechanisms by which prevention efforts operate. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Retention interval and intertrial interval in a serial learning or delayed discrimination task.

In 4 experiments, 58 male albino rats were provided with the same 3-event decreasing series (18-1-0) of food pellets in a runway to investigate tracking—running fast to 18 pellets and running slow to 1 and 0 pellets. Results show that when more than 1 daily trial was given, tracking was acquired more slowly and was disrupted by a shift in retention interval from 15 sec to 5 min. Tracking was also disrupted by a shift from 1 to 2 trials each day. Results indicate that when given 1 18-1-0 trial each day, Ss partitioned events on a 1st-event/subsequent-event basis, that little forgetting occurred even at long retention intervals, that somewhat different memories signaled events when 1 or more than 1 18-1-0 trial occurred each day, and that retention interval deficits could arise owing to the same or similar memories' signaling different events. Results limit the generality of 3 hypotheses suggested by H. L. Roitblat (see record 1983-09709-001) and by S. J. Haggbloom and M. W. Ekdahl (1985): that as retention interval increases, rats find it increasingly difficult to remember and utilize serial position cues; that tracking in serial tasks is not influenced by number of trials each day; and that there are specific stimuli associated with each retention interval that when changed, necessarily disrupt performance. (23 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The second stalk composed of the b- and delta-subunits connects F0 to F1 via an alpha-subunit in the Escherichia coli ATP synthase

The b- and delta-subunits of the Escherichia coli ATP synthase are critical for binding ECF1 to the F0 part, and appear to constitute the stator necessary for holding the alpha3beta3 hexamer as the c-epsilon-gamma domain rotates during catalysis. Previous studies have determined that the b-subunits are dimeric for a large part of their length, and interact with the F1 part through the delta-subunit (Rodgers, A. J. W., Wilkens, S., Aggeler, R., Morris, M. B., Howitt, S. M., and Capaldi, R. A. (1997) J. Biol. Chem. 272, 31058-31064). To further study b-subunit interactions, three mutants were constructed in which Ser-84, Ala-144, and Leu-156, respectively, were replaced by Cys. Treatment of purified ECF1F0 from all three mutants with CuCl2 induced disulfide formation resulting in b-subunit dimer cross-link products. In addition, the mutant bL156C formed a cross-link from a b-subunit to an alpha-subunit via alphaCys90. Neither b-b nor b-alpha cross-linking had significant effect on ATPase activities in any of the mutants. Proton pumping activities were measured in inner membranes from the three mutants. Dimerization of the b-subunit did not effect proton pumping in mutants bS84C or bA144C. In the mutant bL156C, CuCl2 treatment reduced proton pumping markedly, probably because of uncoupling caused by the b-alpha cross-link formation. The results show that the alpha-subunit forms part of the binding site on ECF1 for the b2delta domain and that the b-subunit extends all the way from the membrane to the top of the F1 structure. Some conformational flexibility in the connection between the second stalk and F1 appears to be required for coupled catalysis.     

Odor of Taste Stimuli in Conditioned "Taste" Aversion Learning.

The present research addresses whether rats can express odor aversions to the odor of taste stimuli. In Experiment 1, saccharin or salt were either mixed in distilled water, so the rats could taste and smell them, or presented on disks attached to the tubes' metal spouts so the rats could only smell them. Aversions were established to taste stimuli under both conditions. The results of Experiment 2 indicate that conditioning was to the odor of the tastes when they were presented on disks in Experiment 1, hence both taste and odor aversions were established by means of "taste" stimuli. Taste aversion learning thus may more properly be termed flavor aversion learning, with flavor referring to both taste and odor components. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Significance of concentrations and ratio of immunoglobulin G and M in the evaluation of anti-Toxoplasma IGM

The Authors have tested the significance of the correlation of the mean total IgM concentration, the IgG: IgM ratio and the presence of specific anti-Toxoplasma gondii IgM, determined with different serological reactions. The piece of research has been carried out on 72 samples of subjects with active toxoplasmic infections.     

Adolescent and family predictors of physical aggression, communication, and satisfaction in young adult couples: A prospective analysis.

This study tested a model wherein the family conflict, depression, and antisocial behavior of 254 adolescents (mean age?=?17 years; 63% female) are prospectively related to functioning within a marital (51 %) or dating relationship in young adulthood (mean age?=?23 years). Family aversive communication in adolescence and adolescent antisocial behavior predicted couple physical aggression. Family aversive communication predicted dyadic satisfaction and aversive couple communication for married women and dating men. Among those with partners who reported little antisocial behavior, adolescent antisocial behavior inversely predicted couple satisfaction and facilitative behavior. Partner antisocial behavior did not mediate the relation between adolescent characteristics and couple functioning. Findings emphasize the importance of the early family environment and psychopathology of the adolescent in the development of adaptive couple relationships. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A prospective three generational study of fathers’ constructive parenting: Influences from family of origin, adolescent adjustment, and offspring temperament.

This prospective, intergenerational study considered multiple influences on 102 fathers’ constructive parenting of 181 children. Fathers in the 2nd generation (G2) were recruited as boys on the basis of neighborhood risk for delinquency and assessed through early adulthood. The fathers’ parents (G1) and the G2 mothers of G3 also participated. A multiagent, multimethod approach was used to measure G1 and G2 constructive parenting (monitoring, discipline, warmth, and involvement), G2 positive adolescent adjustment, and problem behavior in all 3 generations, including G3 difficult temperament and externalizing problems in early and middle childhood, respectively. Path modeling supported direct transmission of G1 constructive parenting of G2 in late childhood to G2 constructive parenting of G3 in middle childhood. Of note, G1 parenting indirectly influenced G2 parenting through G2 positive adjustment but not through G2 adolescent antisocial behavior. G1 parenting influenced G2 parenting in both early and middle childhood of G3. G2 parenting influenced G3 problem behavior but not vice versa. Intergenerational continuities in parenting persisted, even when additional influences were considered. Transmission pathways are not limited to life-course adversity. Rather, constructive parenting is maintained, in part, by engendering positive adjustment in offspring. (PsycINFO Database Record (c) 2010 APA, all rights reserved)