Dental care and oral health in Aagenaes syndrome/lymphedema cholestasis syndrome 1.

UNLABELLED: Aagenaes syndrome/lymphedema cholestasis syndrome 1 (LCS1) is a rare genetic disorder characterized by neonatal cholestasis and lymphedema. The aim was to assess dental care and oral health in adults with LCS1. Fifteen (9M, 6F) individuals diagnosed with LCS1, aged 19-59 years participated. The study evaluated salivary secretion rate, dental radiographs, intraoral photos and included a questionnaire. Eight (53%) had regular dental checkups. Three had received subsidized dental care. Seven (47%) had two or more subjective symptoms of xerostomia. Three (20%) had a decreased stimulated salivary secretion rate below 0.7 mL/minute. Seven (47%) had dentin caries. Marginal periodontitis was found in all six patients above 35 years of age, but not before that age. Thirteen (87%) had tooth discoloration, which was extensive in three (20%). CONCLUSION: Several patients with LCS1 have problems with periodontitis and tooth discoloration. Frequent dental checkups are therefore recommended.

Mutations in the NB-ARC domain of I-2 that impair ATP hydrolysis cause autoactivation.

Resistance (R) proteins in plants confer specificity to the innate immune system. Most R proteins have a centrally located NB-ARC (nucleotide-binding adaptor shared by APAF-1, R proteins, and CED-4) domain. For two tomato (Lycopersicon esculentum) R proteins, I-2 and Mi-1, we have previously shown that this domain acts as an ATPase module that can hydrolyze ATP in vitro. To investigate the role of nucleotide binding and hydrolysis for the function of I-2 in planta, specific mutations were introduced in conserved motifs of the NB-ARC domain. Two mutations resulted in autoactivating proteins that induce a pathogen-independent hypersensitive response upon expression in planta. These mutant forms of I-2 were found to be impaired in ATP hydrolysis, but not in ATP binding, suggesting that the ATP- rather than the ADP-bound state of I-2 is the active form that triggers defense signaling. In addition, upon ADP binding, the protein displayed an increased affinity for ADP suggestive of a change of conformation. Based on these data, we propose that the NB-ARC domain of I-2, and likely of related R proteins, functions as a molecular switch whose state (on/off) depends on the nucleotide bound (ATP/ADP).

Rotary movements within the ATP synthase do not constitute an obligatory element of the catalytic mechanism.

After a brief history of the proposals for the mechanism of the ATP synthase, the main experimental arguments for a rotational mechanism of catalysis are analyzed and on the basis of this analysis it is concluded that no evidence has been provided for rotation as an obligatory element of the catalytic mechanism. On the other hand, the experimental evidence in favor of a two-sites catalytic mechanism, derived from various approaches and not compatible with a three-sites rotary mechanism, appear to be very solid. Finally a brief characterization of the various nucleotide binding sites is provided and a suggestion is made how the enzyme has evolutionarily developed from a rotating machine into an asymmetrical device for energy conservation.

Mutagenic and functional analysis of the C-terminus of Saccharomyces cerevisiae Pho84 phosphate transporter.

A widely accepted mechanism for selective degradation of plasma membrane proteins is via ubiquitination and/or phosphorylation events. Such a regulated degradation has previously been suggested to rely on the presence of a specific SINNDAKSS sequence within the protein. Modification of a partly conserved SINNDAKSS-like sequence in the C-terminal tail of the Pho84 phosphate transporter, in combination with C-terminal fusion of green fluorescent protein or a MYC epitope, were used to evaluate the presence of this sequence and its role in the regulated degradation. The functional Pho84 mutants in which this SINNDAKSS-like sequence was altered or truncated were subjected to degradation like that of the wild type, suggesting that degradation of the Pho84 protein is regulated by factors other than properties of this sequence.

Effects of a hexokinase II deletion on the dynamics of glycolysis in continuous cultures of Saccharomyces cerevisiae.

In glucose-limited aerobic chemostat cultures of a wild-type Saccharomyces cerevisiae and a derived hxk2 null strain, metabolic fluxes were identical. However, the concentrations of intracellular metabolites, especially fructose 1,6-bisphosphate, and hexose-phosphorylating activities differed. Interestingly, the hxk2 null strain showed a higher maximal growth rate and higher Crabtree threshold dilution rate, revealing a higher oxidative capacity for this strain. After a pulse of glucose, aerobic glucose-limited cultures of wild-type S. cerevisiae displayed an overshoot in the intracellular concentrations of glucose 6-phosphate, fructose 6-phosphate, and fructose 1,6-bisphosphate before a new steady state was established, in contrast to the hxk2 null strain which reached a new steady state without overshoot of these metabolites. At low dilution rates the overshoot of intracellular metabolites in the wild-type strain coincided with the immediate production of ethanol after the glucose pulse. In contrast, in the hxk2 null strain the production of ethanol started gradually. However, in spite of the initial differences in ethanol production and dynamic behaviour of the intracellular metabolites, the steady-state fluxes after transition from glucose limitation to glucose excess were not significantly different in the wild-type strain and the hxk2 null strain at any dilution rate.