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L Moulinier

Publications and source records attributed to L Moulinier.

At least 19 recordsLinked to original sources
PubMed2001

The structure of an AspRS-tRNA(Asp) complex reveals a tRNA-dependent control mechanism.

The 2.6 A resolution crystal structure of an inactive complex between yeast tRNA(Asp) and Escherichia coli aspartyl-tRNA synthetase reveals the molecular details of a tRNA-induced mechanism that controls the specificity of the reaction. The dimer is asymmetric, with only one of the two bound tRNAs entering the active site cleft of its subunit. However, the flipping loop, which controls the proper positioning of the amino acid substrate, acts as a lid and prevents the correct positioning of the terminal adenosine. The structure suggests that the acceptor stem regulates the loop movement through sugar phosphate backbone- protein interactions. Solution and cellular studies on mutant tRNAs confirm the crucial role of the tRNA three-dimensional structure versus a specific recognition of bases in the control mechanism.

Aspartate-tRNA Ligase↗
PubMed2000

Crystal structure of the ligand-binding domain of the ultraspiracle protein USP, the ortholog of retinoid X receptors in insects.

The major postembryonic developmental events happening in insect life, including molting and metamorphosis, are regulated and coordinated temporally by pulses of ecdysone. The biological activity of this steroid hormone is mediated by two nuclear receptors: the ecdysone receptor (EcR) and the Ultraspiracle protein (USP). The crystal structure of the ligand-binding domain from the lepidopteran Heliothis virescens USP reported here shows that the loop connecting helices H1 and H3 precludes the canonical agonist conformation. The key residues that stabilize this unique loop conformation are strictly conserved within the lepidopteran USP family. The presence of an unexpected bound ligand that drives an unusual antagonist conformation confirms the induced-fit mechanism accompanying the ligand binding. The ligand-binding pocket exhibits a retinoid X receptor-like anchoring part near a conserved arginine, which could interact with a USP ligand functional group. The structure of this receptor provides the template for designing inhibitors, which could be utilized as a novel type of environmentally safe insecticides.

Amino Acid Sequence↗
PubMed2000

A domain in the N-terminal extension of class IIb eukaryotic aminoacyl-tRNA synthetases is important for tRNA binding.

Cytoplasmic aspartyl-tRNA synthetase (AspRS) from Saccharomyces cerevisiae is a homodimer of 64 kDa subunits. Previous studies have emphasized the high sensitivity of the N-terminal region to proteolytic cleavage, leading to truncated species that have lost the first 20-70 residues but that retain enzymatic activity and dimeric structure. In this work, we demonstrate that the N-terminal extension in yeast AspRS participates in tRNA binding and we generalize this finding to eukaryotic class IIb aminoacyl-tRNA synthetases. By gel retardation studies and footprinting experiments on yeast tRNA(Asp), we show that the extension, connected to the anticodon-binding module of the synthetase, contacts tRNA on the minor groove side of its anticodon stem. Sequence comparison of eukaryotic class IIb synthetases identifies a lysine-rich 11 residue sequence ((29)LSKKALKKLQK(39) in yeast AspRS with the consensus xSKxxLKKxxK in class IIb synthetases) that is important for this binding. Direct proof of the role of this sequence comes from a mutagenesis analysis and from binding studies using the isolated peptide.

Amino Acid Sequence↗
PubMed2000

Thermus thermophilus contains an eubacterial and an archaebacterial aspartyl-tRNA synthetase.

Thermus thermophilus possesses two aspartyl-tRNA synthetases (AspRSs), AspRS1 and AspRS2, encoded by distinct genes. Alignment of the protein sequences with AspRSs of other origins reveals that AspRS1 possesses the structural features of eubacterial AspRSs, whereas AspRS2 is structurally related to the archaebacterial AspRSs. The structural dissimilarity between the two thermophilic AspRSs is correlated with functional divergences. AspRS1 aspartylates tRNA(Asp) whereas AspRS2 aspartylates tRNA(Asp), and tRNA(Asn) with similar efficiencies. Since Asp bound on tRNA(Asn) is converted into Asn by a tRNA-dependent aspartate amidotransferase, AspRS2 is involved in Asn-tRNA(Asn) formation. These properties relate functionally AspRS2 to archaebacterial AspRSs. The structural basis of the dual specificity of T. thermophilus tRNA(Asn) was investigated by comparing its sequence with those of tRNA(Asp) and tRNA(Asn) of strict specificity. It is shown that the thermophilic tRNA(Asn) contains the elements defining asparagine identity in Escherichia coli, part of which being also the major elements of aspartate identity, whereas minor elements of this identity are missing. The structural context that permits expression of aspartate and asparagine identities by tRNA(Asn) and how AspRS2 accommodates tRNA(Asp) and tRNA(Asn) will be discussed. This work establishes a distinct structure-function relationship of eubacterial and archaebacterial AspRSs. The structural and functional properties of the two thermophilic AspRSs will be discussed in the context of the modern and primitive pathways of tRNA aspartylation and asparaginylation and related to the phylogenetic connexion of T. thermophilus to eubacteria and archaebacteria.

Acylation↗
PubMed1999

Synthesis of aspartyl-tRNA(Asp) in Escherichia coli--a snapshot of the second step.

The 2.4 A crystal structure of the Escherichia coli aspartyl-tRNA synthetase (AspRS)-tRNA(Asp)-aspartyl-adenylate complex shows the two substrates poised for the transfer of the aspartic acid moiety from the adenylate to the 3'-hydroxyl of the terminal adenosine of the tRNA. A general molecular mechanism is proposed for the second step of the aspartylation reaction that accounts for the observed conformational changes, notably in the active site pocket. The stabilization of the transition state is mediated essentially by two amino acids: the class II invariant arginine of motif 2 and the eubacterial-specific Gln231, which in eukaryotes and archaea is replaced by a structurally non-homologous serine. Two archetypal RNA-protein modes of interactions are observed: the anticodon stem-loop, including the wobble base Q, binds to the N-terminal beta-barrel domain through direct protein-RNA interactions, while the binding of the acceptor stem involves both direct and water-mediated hydrogen bonds in an original recognition scheme.

Anticodon↗
PubMed1999

Effects of joint lavage and steroid injection in patients with osteoarthritis of the knee: results of a multicenter, randomized, controlled trial.

OBJECTIVE: To evaluate the efficacy of joint lavage and intraarticular steroid injection, alone and in combination, in the treatment of patients with symptomatic knee osteoarthritis (OA). METHODS: Ninety-eight patients with painful tibiofemoral OA were enrolled in a prospective, randomized, controlled, 2 x 2 factorial-design trial of 6 months' duration. The 4 treatment groups consisted of 1) intraarticular placebo (1.5 ml of 0.9% normal saline), 2) intraarticular corticosteroids (3.75 mg of cortivazol in 1.5 ml), 3) joint lavage and intraarticular placebo, and 4) joint lavage and intraarticular corticosteroid. Outcome measures evaluated at baseline, week 1, week 4, week 12, and week 24 included severity of pain (100-mm visual analog scale [VAS]), global status (100-mm VAS), and Lequesne's functional index. RESULTS: No interaction between steroid injection and joint lavage was demonstrated. Patients who had undergone joint lavage had significantly improved pain VAS scores at week 24 (P = 0.020). In contrast, corticosteroid injection had no long-term effect (P = 0.313); corticosteroid injection was associated with a decrease in pain only at week 1 (P = 0.003) and week 4 (P = 0.020). After week 4, Lequesne's functional index was not significantly improved regardless of the assigned treatment. CONCLUSION: Compared with placebo, both treatments significantly relieved pain but did not improve functional impairment. The effects of the 2 treatments were additive. Cortivazol provided short-term relief of pain (up to week 4). The effects of joint lavage persisted up to week 24.

Aged↗
PubMed1998

Transmembrane signaling across the ligand-gated FhuA receptor: crystal structures of free and ferrichrome-bound states reveal allosteric changes.

FhuA protein facilitates ligand-gated transport of ferrichrome-bound iron across Escherichia coli outer membranes. X-ray analysis at 2.7 A resolution reveals two distinct conformations in the presence and absence of ferrichrome. The monomeric protein consists of a hollow, 22-stranded, antiparallel beta barrel (residues 160-714), which is obstructed by a plug (residues 19-159). The binding site of ferrichrome, an aromatic pocket near the cell surface, undergoes minor changes upon association with the ligand. These are propagated and amplified across the plug, eventually resulting in substantially different protein conformations at the periplasmic face. Our findings reveal the mechanism of signal transmission and suggest how the energy-transducing TonB complex senses ligand binding.

Allosteric Regulation↗
PubMed1998

Crystal structure of aspartyl-tRNA synthetase from Pyrococcus kodakaraensis KOD: archaeon specificity and catalytic mechanism of adenylate formation.

The crystal structure of aspartyl-tRNA synthetase (AspRS) from Pyrococcus kodakaraensis was solved at 1.9 A resolution. The sequence and three-dimensional structure of the catalytic domain are highly homologous to those of eukaryotic AspRSs. In contrast, the N-terminal domain, whose function is to bind the tRNA anticodon, is more similar to that of eubacterial enzymes. Its structure explains the unique property of archaeal AspRSs of accommodating both tRNAAsp and tRNAAsn. Soaking the apo-enzyme crystals with ATP and aspartic acid both separately and together allows the adenylate formation to be followed. Due to the asymmetry of the dimeric enzyme in the crystalline state, different steps of the reaction could be visualized within the same crystal. Four different states of the aspartic acid activation reaction could thus be characterized, revealing the functional correlation of the observed conformational changes. The binding of the amino acid substrate induces movement of two invariant loops which secure the position of the peptidyl moiety for adenylate formation. An unambiguous spatial and functional assignment of three magnesium ion cofactors can be made. This study shows the important role of residues present in both archaeal and eukaryotic AspRSs, but absent from the eubacterial enzymes.

Acylation↗
PubMed1998

Adhesive capsulitis of the shoulder: an open study of 40 cases treated by joint distention during arthrography followed by an intraarticular corticosteroid injection and immediate physical therapy.

OBJECTIVE: To evaluate the short- and long-term efficacy of joint distention during arthrography followed by an intraarticular corticosteroid injection then by high-intensity physical therapy and use of an abduction splint in an open study of 40 patients with adhesive capsulitis of the shoulder. METHODS: Patients were evaluated on D0, D5 (i.e., before discharge) and D30 for pain severity assessed using a four-point scale (0-3) and for passive ranges of abduction, internal rotation and external rotation of the shoulder. RESULTS: Mean pain severity improved significantly from 2.18 +/- 0.6 (mean +/- SD) on D0 to 1.74 +/- 0.5 on D5 (P: 0.01) and 0.92 +/- 0.5 on D30 (P: 0.02). Passive range of abduction increased significantly from 44.8 degrees +/- 1.54 degrees on D0 to 68 degrees +/- 15 degrees on D5 (P: 0.05), whereas the difference between D5 and D30 (71 degrees +/- 13 degrees) was not significant (P: 0.8). Similarly, passive range of external rotation increased significantly from 4.3 degrees +/- 0.6 degree on D0 to 13.5 degrees +/- 0.5 degree on D5 (P = 0.04) and showed a nonsignificant increase from D5 to D30 (17 degrees +/- 13 degrees, P: 0.2). CONCLUSION: Joint distention during arthrography followed by an intraarticular corticosteroid injection then by high-intensity physical therapy significantly improved pain and passive range of motion within the first five days, and these gains were sustained after one month.

Adrenal Cortex Hormones↗
PubMed1997

The structure of Staphylococcus aureus epidermolytic toxin A, an atypic serine protease, at 1.7 A resolution.

BACKGROUND: Staphylococcal epidermolytic toxins A and B (ETA and ETB) are responsible for the staphylococcal scalded skin syndrome of newborn and young infants; this condition can appear just a few hours after birth. These toxins cause the disorganization and disruption of the region between the stratum spinosum and the stratum granulosum--two of the three cellular layers constituting the epidermis. The physiological substrate of ETA is not known and, consequently, its mode of action in vivo remains an unanswered question. Determination of the structure of ETA and its comparison with other serine proteases may reveal insights into ETA's catalytic mechanism. RESULTS: The crystal structure of staphylococcal ETA has been determined by multiple isomorphous replacement and refined at 1.7 A resolution with a crystallographic R factor of 0.184. The structure of ETA reveals it to be a new and unique member of the trypsin-like serine protease family. In contrast to other serine protease folds, ETA can be characterized by ETA-specific surface loops, a lack of cysteine bridges, an oxyanion hole which is not preformed, an S1 specific pocket designed for a negatively charged amino acid and an ETA-specific specific N-terminal helix which is shown to be crucial for substrate hydrolysis. CONCLUSIONS: Despite very low sequence homology between ETA and other trypsin-like serine proteases, the ETA crystal structure, together with biochemical data and site-directed mutagenesis studies, strongly confirms the classification of ETA in the Glu-endopeptidase family. Direct links can be made between the protease architecture of ETA and its biological activity.

Amino Acid Sequence↗
PubMed1997

Inflammatory rheumatism and nasal polyposis.

We report five cases of seronegative inflammatory rheumatism associated with nasal polyposis. The patients were four women and one man, mean age 49.5 years (range 42-59 yrs.). Two patients had polyarthralgia predominating in the hands, wrists and knees and two patients had symmetrical acromelic polyarthritis. The fifth patient, a woman, had oligoarticular arthritis. In a single female patient, X-rays showed moderate erosions of both tarsometatarsal bones. The inflammatory syndrome was moderate with mean ESR 23 (12-38) and immunological investigations were negative except for the presence of pANCA (50-200 U) in three patients. HLA-A1, B8, and Bw35 antigens were found in three of the five patients. In all cases, nasal and sinus polyposis (NSP) preceded rheumatism and the joint symptoms were accompanied by worsening of the ENT symptoms. NSP was confirmed by CT scan of the nasal fossae and sinuses. Polyps were surgically removed in four patients and the histology showed neither granuloma nor vasculitis. In four patients the joint symptoms, which responded poorly to nonsteroidal anti-inflammatory drugs (NSAIDs), improved markedly after ENT treatment (surgery and topical steroids) and synthetic antimalarials. The concomitant course of the joint and ENT symptoms suggests there may be a link between inflammatory rheumatism and NSP.

Adult↗
PubMed1997

Influence of the volume of osteonecrosis on the outcome of core decompression of the femoral head.

OBJECTIVES: To assess the outcome of core decompression in the treatment of osteonecrosis of the femoral head related to the volume of necrotic bone measured according to a previously reported method. METHODS: Twenty hips corresponding to strictly Ficat stage II underwent magnetic resonance imaging and the volume of necrotic bone was expressed as a percentage of the volume of the entire head measured on each slice. All hips underwent core decompression and the outcome was evaluated at 24 months. The primary evaluation criterion was radiological appearance: the outcome was considered as good if the hip remained stage II and poor if the disease progressed. RESULTS: Twenty four months after core decompression, half the cases remained stable and in half the disease had progressed. Outcome seemed to be related to the volume of necrotic bone (average 22% in the good outcome group versus 45% in the poor outcome group (p = 0.0051)) and was independent of risk factors, age, and histological type. CONCLUSIONS: The volume of necrotic bone should be taken into account in the evaluation of any treatment, bearing in mind that in more than one third of cases this volume will probably decrease, especially at the beginning of the disease process.

Adult↗
PubMed1997

Phosphate excretion in reflex sympathetic dystrophy syndrome before and after a single infusion of pamidronate.

To clarify the relations between reflex sympathetic dystrophy syndrome and moderate phosphate diabetes, we prospectively determined urinary phosphate excretion parameters (clearance, renal tubular reabsorption of phosphate and threshold of tubular reabsorption of phosphate) in 37 patients with reflex sympathetic dystrophy syndrome before and after treatment with 60 mg of pamidronate (n = 23) and in 35 age- and sex-matched controls. Urinary phosphate excretion parameters were identical in cases and in controls. Fourteen of the 23 cases treated by pamidronate were improved after one to two months. Pamidronate had no effect on phosphate excretion. Four cases versus only one control had phosphate diabetes (X2 = 0.18). Three of the four cases with phosphate diabetes failed to respond to pamidronate therapy but improved under phosphate and 1,25-diOH vitamin D3 therapy.

Adult↗
PubMed1997

Osteoporotic vertebral fractures in a man under high-dose inhaled glucocorticoid therapy. A case-report with a review of the literature.

A 65-year-old man had surgery in June 1995 for femoral neuralgia. The plain films of the spine were normal at the time. In September of the same year, when he was beginning to walk gradually longer distances, he started experiencing back pain. Crush fractures of T8 and L2 were seen on plain films. His pain worsened, and he was admitted in December 1995. A third set of plain films disclosed fractures of all the vertebral bodies from T8 through L5, with increased density of the endplates of the same vertebras. Serum and urinary levels of calcium and phosphate were normal. Dual-energy X-ray absorptiometry demonstrated osteoporosis predominating in the trabecular bone. Evidence of increased bone resorption was seen on the histomorphometric study. Large amounts of dihydroxypyridinoline were found in the urine. Investigations for the classical causes of osteoporosis in males were unrewarding. Careful questioning revealed that the patient had been taking inhaled beclomethasone for seven years to treat chronic obstructive lung disease. Serum levels of cortisol and ACTH were low, consistent with a diagnosis of treatment-induced hypercorticism. To our knowledge, this is the first reported case of osteoporotic vertebral fractures in a male due to inhaled glucocorticoid therapy. Inhaled glucocorticoids are generally believed to induce only minimal systemic effects. However, decreased serum osteocalcin levels and increased urinary excretion of bone resorption markers have been reported in patients under inhaled beclomethasone therapy. Low spinal bone mineral density values correlated with the degree of pituitary-adrenal gland suppression as evaluated using the ACTH test have also been found in several groups of patients treated with inhaled glucocorticoids.

Administration, Inhalation↗
PubMed1996

Membranoproliferative glomerulonephritis, p-antineutrophil cytoplasmic antibodies, and rheumatoid arthritis. Report of a case.

Many rheumatoid arthritis patients have renal dysfunction induced either by the drugs used to treat their joint disease or by the chronic inflammation. A case of rheumatoid arthritis with p-antineutrophil cytoplasmic antibodies and mesangial glomerulonephritis that progressed to type I membranoproliferative glomerulonephritis is reported. The glomerular abnormalities were diagnosed by two renal biopsies done at a one-year interval. Reasons for the first and second renal biopsies were renal dysfunction with hematuria and impure nephrotic syndrome, respectively. Unusual features in this case include the succession of two histologic forms of glomerular disease in a patient with rheumatoid arthritis, the correlation between p-antineutrophil cytoplasmic antibody titers and activity of the renal disease. In addition, type I membranoproliferative glomerulonephritis is exceedingly rare in rheumatoid arthritis patients.

Aged↗
PubMed1996

Pamidronate infusions for the treatment of Paget's disease of bone.

Effective pamidronate dosages in Paget's disease of bone have not yet been determined. We prospectively compared two pamidronate dosages (60 mg and 120 mg) in 26 patients whose baseline alkaline phosphatase level was at least two-fold the upper limit of normal. Pamidronate was given as three-hour infusions of 60 mg each. Follow-up was two years. The two groups were comparable at baseline except for higher alkaline phosphatase and hydroxyproline levels in the group treated with 120 mg pamidronate. Efficacy on laboratory parameters was greater in the higher dosage group. Osteocalcin levels showed little change. In both dosage groups, alkaline phosphatase levels fell significantly versus baseline, and the difference persisted throughout the two-year follow-up. Urinary hydroxyproline excretion remained significantly reduced versus baseline during the first 12 months and rose subsequently. A return to normal of the two study parameters six months after treatment was associated with longer duration of the biologic treatment response. A survival curve analysis confirmed this finding and suggested that a return to normal of laboratory parameters was predictive of clinical remission. The drug was well tolerated. Adverse effects were mild and similar to those recorded during earlier studies.

Aged↗