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Several anions such as Cl-, NO2(-), SO4(2-), and PO4(3-) are known to modulate the photosynthetic activity. Moreover, the chloroplast metabolism requires the exchange of both inorganic and organic (e.g., triose phosphate, dicarboxylic acid, ATP) anions between the cytoplasm and the stroma. A chloride channel form the chloroplast envelope was reconstituted in planar lipid bilayers. We show that the channel is active in conditions prevailing in the plant. The open probability increases with the ionic strength of the experimental solutions and is maximal at 0 mV. This suggests that the channel could play a role in the osmotic regulation of the chloroplast. Amino group reagents affect the channel activity in a way that demonstrated that lysine residues are important for channel gating but not for ATP binding. Together, our results provide new information on the functioning of this channel in the chloroplast envelope membranes. They indicate that the open probability of the channel is low (Po < or = 0.2) in vivo and that this channel can account for the chloride flux through the chloroplast envelope.

The development of chloroplasts and the integration of their function within a plant cell rely on the presence of a complex biochemical machinery located within their limiting envelope membranes. To provide the most exhaustive view of the protein repertoire of chloroplast envelope membranes, we analyzed this membrane system using proteomics. To this purpose, we first developed a procedure to prepare highly purified envelope membranes from Arabidopsis chloroplasts. We then extracted envelope proteins using different methods, i.e. chloroform/methanol extraction and alkaline or saline treatments, in order to retrieve as many proteins as possible, from the most to least hydrophobic ones. Liquid chromatography tandem mass spectrometry analyses were then performed on each envelope membrane subfraction, leading to the identification of more than 100 proteins. About 80% of the identified proteins are known to be, or are very likely, located in the chloroplast envelope. The validation of localization in the envelope of two phosphate transporters exemplifies the need for a combination of strategies to perform the most exhaustive identification of genuine chloroplast envelope proteins. Interestingly, some of the identified proteins are found to be Nalpha-acetylated, which indicates the accurate location of the N terminus of the corresponding mature protein. With regard to function, more than 50% of the identified proteins have functions known or very likely to be associated with the chloroplast envelope. These proteins are a) involved in ion and metabolite transport, b) components of the protein import machinery, and c) involved in chloroplast lipid metabolism. Some soluble proteins, like proteases, proteins involved in carbon metabolism, or proteins involved in responses to oxidative stress, were associated with envelope membranes. Almost one-third of the proteins we identified have no known function. The present work helps understanding chloroplast envelope metabolism at the molecular level and provides a new overview of the biochemical machinery of the chloroplast envelope membranes.

Proteomics is a very powerful approach to link the information contained in sequenced genomes, like Arabidopsis, to the functional knowledge provided by studies of plant cell compartments, such as chloroplast envelope membranes. This review summarizes the present state of proteomic analyses of highly purified spinach and Arabidopsis envelope membranes. Methods targeted towards the hydrophobic core of the envelope allow identifying new proteins, and especially new transport systems. Common features were identified among the known and newly identified putative envelope inner membrane transporters and were used to mine the complete Arabidopsis genome to establish a virtual plastid envelope integral protein database. Arabidopsis envelope membrane proteins were extracted using different methods, that is, chloroform/methanol extraction, alkaline or saline treatments, in order to retrieve as many proteins as possible, from the most to the less hydrophobic ones. Mass spectrometry analyses lead to the identification of more than 100 proteins. More than 50% of the identified proteins have functions known or very likely to be associated with the chloroplast envelope. These proteins are (a) involved in ion and metabolite transport, (b) components of the protein import machinery and (c) involved in chloroplast lipid metabolism. Some soluble proteins, like proteases, proteins involved in carbon metabolism or in responses to oxidative stress, were associated with envelope membranes. Almost one third of the newly identified proteins have no known function. The present stage of the work demonstrates that a combination of different proteomics approaches together with bioinformatics and the use of different biological models indeed provide a better understanding of chloroplast envelope biochemical machinery at the molecular level.

The large majority of plastid proteins are nuclear-encoded and, thus, must be imported within these organelles. Unlike most of the outer envelope proteins, targeting of proteins to all other plastid compartments (inner envelope membrane, stroma, and thylakoid) is strictly dependent on the presence of a cleavable transit sequence in the precursor N-terminal region. In this paper, we describe the identification of a new envelope protein component (ceQORH) and demonstrate that its subcellular localization is limited to the inner membrane of the chloroplast envelope. Immunopurification, microsequencing of the natural envelope protein and cloning of the corresponding full-length cDNA demonstrated that this protein is not processed in the N-terminal region during its targeting to the inner envelope membrane. Transient expression experiments in plant cells were performed with truncated forms of the ceQORH protein fused to the green fluorescent protein. These experiments suggest that neither the N-terminal nor the C-terminal are essential for chloroplastic localization of the ceQORH protein. These observations are discussed in the frame of the endosymbiotic theory of chloroplast evolution and suggest that a domain of the ceQORH bacterial ancestor may have evolved so as to exclude the general requirement of an N-terminal plastid transit sequence.

A two-membrane system, or envelope, surrounds plastids. Because of the integration of chloroplast metabolism within the plant cell, the envelope is the site of many specific transport activities. However, only a few proteins involved in the processes of transport across the chloroplast envelope have been identified already at the molecular level. To discover new envelope transporters, we developed a subcellular proteomic approach, which is aimed to identify the most hydrophobic envelope proteins. This strategy combined the use of highly purified and characterized membrane fractions, extraction of the hydrophobic proteins with organic solvents, SDS/PAGE separation, and tandem mass spectrometry analysis. To process the large amount of MS/MS data, a blast-based program was developed for searching in protein, expressed sequence tag, and genomic plant databases. Among the 54 identified proteins, 27 were new envelope proteins, with most of them bearing multiple alpha-helical transmembrane regions and being very likely envelope transporters. The present proteomic study also allowed us to identify common features among the known and newly identified putative envelope inner membrane transporters. These features were used to mine the complete Arabidopsis genome and allowed us to establish a virtual plastid envelope integral protein database. Altogether, both proteomic and in silico approaches identified more than 50 candidates for the as yet previously uncharacterized plastid envelope transporters. The predictable function of some of these proteins opens up areas of investigation that may lead to a better understanding of the chloroplast metabolism. The present subcellular proteomic approach is amenable to the analysis of the hydrophobic core of other intracellular membrane systems.

Using mass-spectrometric measurements of 18O exchange from 13C18O2 we determined the activity of carbonic anhydrase (CA; EC 4.2.1.1) in chloroplast envelope membranes isolated from Chlamydomonas reinhardtii cw-15. Our results show an enrichment of CA activity in these fractions relative to the activity in the crude chloroplast. The envelope CA activity increased about 8-fold during the acclimation to low-CO2 conditions and was completely induced within the first 4 h after the transfer to air levels of CO2. The CA-activity was not dissociated from envelope membranes after salt treatment. In addition, no cross-reactivity with other CA isoenzymes of Chlamydomonas was observed in our chloroplast envelope membranes. All these observations indicated that the protein responsible for this activity was a new CA isoenzyme, which was an integral component of the chloroplast envelopes from Chlamydomonas. The catalytic properties of the envelope CA activity were completely different from those of the thylakoid isoenzyme, showing a high requirement for Mg2+ and a high sensitivity to ethoxyzolamide. Analysis of the integral envelope proteins showed that there were no detectable differences between high- and low-inorganic carbon (Ci) cells, suggesting that the new CA activity was constitutively expressed in both high- and low-Ci cells. Two different high-Ci-requiring mutants of C. reinhardtii, cia-3 and pmp-1, had a reduced envelope CA activity. We propose that this activity could play a role in the uptake of inorganic carbon at the chloroplast envelope membranes.

As a complementary approach to genome projects, proteomic analyses have been set up to identify new gene products. One of the major challenges in proteomics concerns membrane proteins, especially the minor ones. A procedure based on the differential extraction of membrane proteins in chloroform/methanol mixtures, was tested on the two different chloroplast membrane systems: envolope and thylakoid membranes. Combining the use of classical sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and mass spectrometry analyses, this procedure enabled identification of hydrophobic proteins. The propensity of hydrophobic proteins to partition in chloroform/methanol mixtures was directly correlated with the number of amino acid residues/number of putative transmembrane regions (Res/TM ratio). Regardless of the particular case of some lipid-interacting proteins, chloroform/methanol extractions allowed enrichment of hydrophobic proteins and exclusion of hydrophilic proteins from both membrane systems, thus demonstrating the versatility of the procedure.

Using a subcellular-specific proteomic approach, we have identified by protein microsequencing, a putative 35-kDa annexin from among the chloroplast envelope polypeptides. To confirm this identification, we demonstrate that (a) a 35-kDa protein, identified as annexin by antibody cross-reactivity, co-purifies with Percoll-purified chloroplasts and their envelope membranes when extracted in the presence of Ca(2+) and (b) the native spinach annexin protein binds to chloroplast-specific lipids in a Ca(2+)-dependent manner. The binding of the spinach annexin to these glycerolipids occurs at similar Ca(2+) concentrations as those, which promote the interaction of annexins to phospholipids in other membranes. Among chloroplast glycerolipids known to be accessible on the cytosolic face (outer leaflet) of the outer envelope membrane, sulfolipid, and probably phosphatidylinositol, would be the sole candidates for a putative Ca(2+)-dependent interaction of annexin with the chloroplast surface., (Copyright 2000 Academic Press.)

A previous study byKAPPELER (1993) showed that no reconciliation occurred in the ringtailed lemur (Lemur catta). Like the majority of studies dealing with reconciliation, the post-conflict period lasted 10 minutes. An identical study using a 70-min post-conflict period was conducted on one of the same semi-free ranging group studied six years earlier byKAPPELER. Results showed that individuals who never interacted within 10 min did engage in friendly interactions in the longer lasting postconflict period.

One hundred and 16 patients contributed to an analysis of the impact of the consequences of severe haemophilia A or B (factor levels < 2%) on orthopaedic status, resources consumed in relation to this status and resultant cost, and quality of life as perceived by the patient, using the MOS 36-Item-Short-Form Health Survey (SF-36). This French cross-sectional study involved outpatients regularly attending a haemophilia treatment centre. Data were collected retrospectively over a period of 1 year by the physician of the haemophilia treatment centre. Patients had a mean age of 23, and consisted of 50% students, 25% salaried workers, 17.2% with no professional activity and 7.8% physically impaired; 82.8% of them had type A haemophilia. Mean pain score was 2.5 per patient for the six main joints; 7.7 for the clinical score and 18.8 for the radiological score, with a mean number of bleeds of 16.3 per year per patient. During the year prior to inclusion, and because of their orthopaedic status, 22.4% of patients were hospitalized, 76.7% attended for an outpatient visit and 76.7% required at least one special investigation; 97.4% received replacement therapy, 41.4% required treatment for joint pain and 42.2% orthopaedic equipment. The less affected dimensions were the physical function (76.8 +/- 22. 2) and the social relations (76.1 +/- 23.1). Least good quality of life scores concerned the pain (60.2 +/- 25.2), perception of general health (59.3 +/- 23.1) and vitality (57.8 +/- 19.5) dimensions. The age was a discriminant criterion since quality of life was better in patients of the 18-23 age group for five dimensions. Mean annual treatment costs of a patient with severe haemophilia were determined as 425 762 French francs ($73 029). Loss of production was estimated at a mean of 4609 French francs ($791) per active patient over the course of the year. Results showed indirect evidence of the usefulness of early home treatment.

The aim of this study was to analyze the characteristics of patients on long-term continuous positive pressure therapy for obstructive sleep apnea in order to determine the efficacy, observance, tolerance, degree of patient satisfaction and patient quality of life using the Nottingham scale. A questionnaire was sent to 939 patients treated for at least six months in 11 centers. Factorial analysis of multiple correspondences and two classification analyses were used to establish patient profiles. Factorial analysis evidenced a relationship between patient satisfaction, reduced symptoms, observance and tolerance. The classification analyses distinguished three groups. Group A (n = 596) included primarily men (93%) who were satisfied with the treatment (99%) and showed good observance. Group B (n = 284) was characterized by patient satisfaction, observance, improved symptoms and lower quality of life than group A. Group C was composed of older patients who were satisfied with their treatment and showed good observance but who had no notable improvement in their symptoms. In conclusion, this study pointed out the difficulty in defining which patients with obstructive sleep apnea would benefit most from continuous positive pressure therapy. Good observance is not a sufficient criterion for therapeutic efficacy.

Identification of rare hydrophobic membrane proteins is a major biological problem that is limited by the specific biochemical approaches required to extract these proteins from membranes and purify them. This is especially true for membranes, such as plastid envelope membranes, that have a high lipid content, present a wide variety of specific functions and therefore contain a large number of unique, but minor, proteins. We have optimized a procedure, based on the differential solubilization of membrane proteins in chloroform/methanol mixtures, to extract and concentrate the most hydrophobic proteins from chloroplast envelope membrane preparations, while more hydrophilic proteins were excluded. In addition to previously characterized chloroplast envelope proteins, such as the phosphate/triose phosphate translocator, we have identified new proteins that were shown to contain putative transmembrane alpha-helices. Moreover, using different chloroform/methanol mixtures, we have obtained differential solubilization of envelope proteins as a function of their hydrophobicity. All the proteins identified were genuine chloroplast envelope proteins, most of them being localized within the inner membrane. Our procedure enables direct mapping (by classical SDS-PAGE) and identification of hydrophobic membrane proteins, whatever their isoelectric point was, that are minor components of specific subcellular compartments. Thus, it complements other techniques that give access to peripheral membrane proteins. If applied to various cell membranes, it is anticipated that it can expedite the identification of hydrophobic proteins involved in transport systems for ions or organic solutes, or it may act as signal receptors or to control metabolic processes and vesicle trafficking.

Peripheral arterial occlusive disease of the lower limbs results in increased risks of cardiovascular and cerebrovascular morbidity and mortality. However, peripheral arterial disease also has an incapacitating effect upon patients' daily lives, and indeed can have considerable consequences upon their quality of life as well as upon their professional activities. The purpose of this study was to describe patients in terms of their professional activities, the consequences of the disease upon such activities, need for external assistance, and the effects of treatment over a six-month treatment follow-up period. This was a prospective, randomised, double-blind, multicentre study comparing naftidrofuryl (three 200-mg tablets per day) versus placebo in patients presenting with stage-II peripheral arterial disease. Four study visits were scheduled for each patient: an initial selection visit, followed by a 30-day placebo wash-out period, an inclusion visit (to allow verification of inclusion and non-inclusion criteria), and follow-up visits after 3 and 6 months of treatment. 234 patients were included in the study in intention to treat (117 patients in the naftidrofuryl group and 117 patients in the placebo group). These two groups were entirely comparable for all criteria (sociodemographic criteria, risk factors, cardiovascular history, duration of disease) except for obesity and dyslipidaemia, for which prevalence was higher in the naftidrofuryl group. 12.4% of the study population were professionally active at the time of the survey (mean age: 65.9 years). However, 42.3% of patients had in fact been active at the time when arterial disease became manifest. Of these patients, 45.4% (45 patients) stated that arterial disease had affected their professional activity: 28.9% (13 patients) reported a change in their activity, 26.7% (12 patients) reported partial suspension of their activity, and 44.4% (20 patients) stated that all professional activities had ceased. Changes in professional activity comprised invalidity (36.2%), prolonged sick leave (25.5%), premature retirement (14.9%), sick leave (17%), unemployment (6.4%), reduction in long-distance travel (4.3%), change of job (8.5%) or salary reduction (2.1%). During the 6-month follow-up period, only 4 patients were on sick leave (3 in the placebo group and 1 in the naftidrofuryl group). Furthermore, less than 10% of the study population required external assistance as a result of the disease. This analysis thus highlights the repercussions of this disease upon the patients' daily and professional activities.

We have isolated a protein, mature RRFHCP, from chloroplasts of spinach (Spinacia oleracea L.) that shows 46% sequence identity and 66% sequence homology with ribosome recycling factor (RRF) of Escherichia coli. RRF recycles ribosomes through disassembly of the posttermination complex. From the cDNA analysis and from the amino-terminal sequencing of the isolated protein, the mature RRFHCP was deduced to have a Mr of 21,838 with 193 aa. It lacks the 78-aa chloroplast targeting sequence encoded by the RRFHCP cDNA sequence. The RRFHCP synthesized in vitro was imported into isolated chloroplasts with simultaneous conversion to the mature RRFHCP. Transcription of the gene coding for RRFHCP was not dependent on light, yet it was limited mostly to photosynthetic tissues in which only one transcript size was detected. Mature RRFHCP exerted a bactericidal effect on E. coli carrying temperature-sensitive RRF at the permissive temperature whereas wild-type E. coli was not affected.

Objectives: The aim of this study was to assess the cost of the first management of inflammatory bowel disease (IBD) from the onset of first symptoms until 6 weeks after the diagnosis. This cost was calculated in French francs (FF) for all IBD and namely for Crohn's disease (CD), ulcerative colitis (UC), and ulcerative proctitis (UP)., Material and Methods: Data concerning 258 patients were collected by the mean of a standardized questionnaire from 3 different sources: the patient, his general practitioner, and his gastroenterologist., Results: Two hundred and fifty eight patients were included: 144 CD (55.8%), 76 UC (29.5%), 30 UP (11.6%), and 8 chronic unclassifiable colitis (CUC) (3.1%). The mean direct costs of the diagnosis (m +/- SD) were 23,116 +/- 40,820 FF for CD, 10,628 +/- 17,316 FF for UC and 3,451 +/- 2,743 FF for UP. Although unplanned hospitalizations occurred in only 38% of the patients (98/258), they represented the 3/4 of the mean costs: 78.2% for CD and 64% for UC. Indirect costs generated by days off work were 4,719 +/- 6,610 FF for CD, 2,996 +/- 6,897 FF for UC and 1,230 +/- 3,622 FF for UP., Conclusion: The first management of a patient with CD was twice more expensive than the one with UC and 6.5 times than the one with UP.

A synthetic gene encoding the mature spinach- chloroplast O-acetylserine (thiol)-lyase was constructed and expressed in an Escherichia coli strain carrying the T7 RNA polymerase system. The pure recombinant protein was obtained at high yield (6 mg/l cell culture) using a new purification procedure that includes affinity chromatography on Green A agarose. Its specific activity was of the order of 1000 U/mg, and its physical properties were similar to those previously reported for the natural enzyme isolated from spinach chloroplasts. In particular the recombinant enzyme, as for the natural enzyme, behaved as a homodimer composed of two identical subunits each of Mr 35000. From steady-state kinetic studies using sulfide or 5-thio(2-nitrobenzoate) (Nbs) as alternative nucleophilic co-substrates, the enzyme exhibited positive kinetic co-operativity with respect to O-acetylserine [Ser(Ac)] in the presence of sulfide and a negative kinetic co-operativity in the presence of Nbs. Binding of Ser(Ac) to the enzyme was also investigated by absorbance and fluorescence measurements to obtain insight into the role of pyridoxal 5'-phosphate and of the single tryptophan residue (Trp176) present in the enzyme molecule. Addition of Ser(Ac) to the enzyme provoked the disappearance of the 409-nm absorbance band of the pyridoxal 5'-phosphate Schiff base and the appearance of two new absorbance bands, the one located between 320 nm and 360 nm and the other centered at 470 nm. Also, the fluorescence emission of the pyridoxal 5'-phosphate Schiff base was quenched upon addition of Ser(Ac) to the enzyme. These changes were most presumably due to the formation of a Schiff base intermediate between alpha-aminoacrylate and the pyridoxal 5'-phosphate cofactor. The fluorescence emission of Trp176 was also quenched upon Ser(Ac) binding to the enzyme. Quantitative analysis of the absorbance and fluorescence equilibrium data disclosed a co-operative behavior in Ser(Ac) binding, in agreement with the steady-state kinetic results. Fluorescence quenching experiments with the acrylamide and iodide revealed that the indole ring of Trp176 was largely exposed and located within the pyridoxal 5'-phosphate active site. These results are consistent with the finding that the native enzyme is composed of two identical subunits. Yet, presumably due to subunit-subunit interactions, the enzyme exhibits two non-equivalent pyridoxal-5'-phosphate-containing active sites.

The subcellular localization of O-acetyiserine(thiol)lyase (EC 4.2.99.8) in nongreen tissue from higher plants has been studied using purified proplastids, mitochondria, and protoplasts from cauliflower (Brassica oleracea L.) buds as a source of subcellular fractions. O-Acetylserine(thiol)lyase has been detected in both organelles (proplastids and mitochondria) and a cytosolic extract obtained by protoplast fractionation. We confirmed these observations, demonstrating that a form of the enzyme different in global charge and separated from others by anion-exchange chromatography corresponded to each subcellular location. Our observations are consistent with the need for cysteine biosynthesis in each subcellular compartment where the synthesis of proteins occurs.