[The hidradenocarcinoma of the wrist - an extremely rare malignant carcinoma: case presentation and literature review]. / Das Hidradenokarzinom des Handgelenkes - ein extrem seltener maligner Tumor: Falldarstellung und Literaturübersicht.

Hidradenocarcinomas are rare, yet highly malignant tumors of eccrine sweat gland origin. Due to its locally aggressive growth and likelihood for metastasis it should be considered as a differential diagnosis especially in case of suspicious intraoperative findings. We report the case of a 73-year-old female patient presenting with a hidradenocarcinoma of the wrist. Treatment of hidradenocarcinomas is similar to the treatment of sarcomas: The first step is an incisional biopsy and obtaining an expert second opinion on the histopathological diagnosis as well as staging. The second step is a clear margin resection of the tumor and the plastic-surgical reconstruction. A long-term follow-up is mandatory to detect potential recurrence or metastasis.

Developmental- and tissue-specific expression of an inhibitor of apoptosis protein 1 homologue from Aedes triseriatus mosquitoes.

We have identified a homologue of the Drosophila inhibitor of apoptosis protein 1 in Aedes triseriatus mosquitoes (designated AtIAP1). The AtIAP1 gene maps to a single locus on chromosome 2. The translation product is a 403 amino acid protein that contains two baculovirus IAP repeat (BIR) domains and a RING finger motif. AtIAP1 mRNA was detectable by RT-PCR amplification in all the mosquito developmental stages (embryos, first-fourth instar larvae, early and late pupae, adults) and adult tissues (midguts, ovaries) examined. In contrast, immunoblots with AtIAP1-specific antibodies revealed that the protein was detectable only in certain developmental stages (first instar larvae, early pupae, adults) and tissues (ovaries). AtIAP1-specific serum also recognized proteins in Ae. aegypti, Ae. albopictus and Culex tritaeniorhynchus. Immunoblot analysis revealed that similar amounts of IAP1 were expressed in LaCrosse virus infected and uninfected Ae. albopictus cell cultures.

[Arterial hypertension secondary to curable causes in adults]. / Hypertensions artérielles secondaires à des causes curables chez l'adulte.

EXTENSIVE AND COSTLY INVESTIGATIONS: Are not warranted in the vast majority of hypertensive patients. Characteristics identifying the patients at risk for secondary hypertension can be used to define the small percentage of patients with hypertension who require more extensive diagnostic testing and management of their condition. Exposure to certain medicines, foods or drugs may cause reversible rises in blood pressure. Renovascular and adrenal diseases cause curable forms of hypertension. IN MANY CASES, THE PATIENT'S HISTORY: Examination and simple tests can detect such exposures and disorders. Checking for secondary hypertension is therefore an early step required for the management of all patients with hypertension, provided it is based on clinical signs and inexpensive tests. This primary screening cannot exclude the possibility of renovascular or adrenal disease in a small number of asymptomatic patients. The risk of missing a diagnosis is acceptable provided that blood pressure is normalized by non-specific antihypertensive treatment. However, more extensive etiologic investigation is required in patients who subsequently develop resistant hypertension. This secondary screening requires imaging and biochemical tests that are not required for primary screening. CORRECTION OF THE CAUSES: Of secondary forms of hypertension may restore blood pressure to normal. The patient's age affects the reversibility of renovascular and adrenal hypertension after etiologic treatment: the younger the patient, the higher the probability of blood pressure normalization.

Genetic heterogeneity of familial hyperkalaemic hypertension.

BACKGROUND: Familial hyperkalaemic hypertension (FHH) is a Mendelian form of low-renin hypertension characterized by hyperkalaemia and hyperchloraemic acidosis despite a normal glomerular filtration rate. To date, three different loci have been identified, on chromosomes 1, 17 and 12. OBJECTIVE: To test for genetic linkage between the three FHH loci and three new affected kindreds. DESIGN AND METHODS: Clinical, biological and genetic analyses were made of three kindreds, including 11 affected individuals among 25 members. Genotyping was performed using four series of microsatellite markers spanning the chromosomes 1, 17 and 12 loci, and the thiazide-sensitive Na-Cl cotransporter (SLC12A3) gene. RESULTS: Segregation of the trait in each kindred was compatible with an autosomal transmission, the affected individuals displaying reasonably consistent biochemical abnormalities and the expected variability in arterial hypertension. Multipoint linkage analysis excluded linkage with the four candidate loci in kindreds 1 and 2, but not with the chromosome 1 locus in kindred 3. CONCLUSION: These results demonstrate further genetic heterogeneity and that a fourth gene is responsible for FHH in at least two unrelated kindreds. They suggest a variety of molecular defects leading to FHH.

Reference scales for the characterization of cationic electrophiles and neutral nucleophiles.

Twenty-three diarylcarbenium ions and 38 pi-systems (arenes, alkenes, allyl silanes and stannanes, silyl enol ethers, silyl ketene acetals, and enamines) have been defined as basis sets for establishing general reactivity scales for electrophiles and nucleophiles. The rate constants of 209 combinations of these benzhydrylium ions and pi-nucleophiles, 85 of which are first presented in this article, have been subjected to a correlation analysis to determine the electrophilicity parameters E and the nucleophilicity parameters N and s as defined by the equation log k(20 degrees C) = s(N + E) (Mayr, H.; Patz, M. Angew. Chem., Int. Ed. Engl. 1994, 33, 938-957). Though the reactivity scales thus obtained cover more than 16 orders of magnitude, the individual rate constants are reproduced with a standard deviation of a factor of 1.19 (Table 1). It is shown that the reactivity parameters thus derived from the reactions of diarylcarbenium ions with pi-nucleophiles (Figure 3) are also suitable for characterizing the nucleophilic reactivities of alkynes, metal-pi-complexes, and hydride donors (Table 2) and for characterizing the electrophilic reactivities of heterosubstituted and metal-coordinated carbenium ions (Table 3). The reactivity parameters in Figure 3 are, therefore, recommended for the characterization of any new electrophiles and nucleophiles in the reactivity range covered. The linear correlation between the electrophilicity parameters E of benzhydryl cations and the corresponding substituent constants sigma(+) provides Hammett sigma(+) constants for 10 substituents from -1.19 to -2.11, i.e., in a range with only very few previous entries.

Phenotypic and genetic heterogeneity of familial hyperkalaemic hypertension (Gordon syndrome).

1. Familial hyperkalaemic hypertension (FHH), also called pseudohypoaldosteronism type II (PHA2) or Gordon syndrome, is a rare Mendelian-form of low-renin hypertension. The first cases of FHH were reported approximately 30 years ago and they described the peculiar biochemical abnormalities (i.e. hyperkalaemia and hyperchloraemic acidosis despite a normal glomerular filtration rate). 2. Since then, more than 90 single cases and families have been reported in the literature. These various reports show marked differences in phenotype. 3. Our group has now collected 14 unrelated pedigrees originating from different parts of France and Europe. We confirm the large variations in the age of discovery and in the severity of the biochemical abnormalities from one individual to another and from one family to another one. 4. Blood pressure levels have no significant relationship with hyperkalaemia or hyperchloraemia, but there is a positive relationship with age, as in the normal population. 5. Analyses of clinical features and Mendelian segregation in our families demonstrate autosomal-dominant inheritance, as expected from the literature. 6. Efforts have been made in the past years to unravel the gene responsible for the disease. Until now, a primary responsibility of the gene encoding the thiazide-sensitive Na-Cl cotransporter (SLC12A3) has been excluded in PHA2 families. Three loci have been identified on chromosomes 1 (PHA2A), 17 (PHA2B) and 12 (PHA2C). 7. More recently, analysis of three additional pedigrees, including 10 affected subjects, with over 25 members allowed us to demonstrate further genetic heterogeneity and the existence of at least a fourth locus. 8. The genetic heterogeneity of this syndrome, and thus the variety of molecular defects, suggests the role of either several new components of the same pathway, multiple aldosterone- regulated effectors or direct or indirect partners of the Na-Cl cotransporter.

Is primary aldosteronism underdiagnosed in clinical practice?

1. Primary aldosteronism is a syndrome consisting of hypertension, suppressed renin activity or concentration and high aldosterone levels in plasma or urine. The main steps in diagnosis are the determination of renin and aldosterone levels, the demonstration of renin-aldosterone dissociation and discrimination between idiopathic hyperplasia and Conn's adenoma, with only Conn's adenoma amenable to surgery. 2. Patients with resistant hypertension and/or hypokalaemia should be screened for primary aldosteronism with simple, redundant hormonal tests. The aldosterone to renin ratio is a logical initial screening test, a high ratio demonstrating renin-aldosterone dissociation. Criteria for a high ratio should be determined in each laboratory. 3. In patients with documented primary aldosteronism, computed tomography scan and adrenal vein sampling help to distinguish between idiopathic hyperplasia and Conn's adenoma. 4. Patients with low renin hypertension, idiopathic hyperplasia and Conn's adenoma have overlapping values for plasma concentrations of potassium, renin and aldosterone and the aldosterone to renin ratio. Because primary aldosteronism subtypes are quantitative diseases, the true prevalence of primary aldosteronism cannot be defined. 5. The use of sensitive screening tests (e.g. aldosterone to renin ratio) gives a higher prevalence of diagnosed cases of primary aldosteronism, but not of surgically correctable forms. Therefore, there is no clinical evidence that primary aldosteronism is underdiagnosed. 6. There is a need for tests to predict the postoperative blood pressure outcome of surgery in subjects with Conn's adenoma.

[Hypertension and primary hyperaldosteronism]. / Hypertension artérielle des hyperaldostéronismes primaires.

Hypokalaemic hypertension or resistant hypertension justify investigation for primary hyperaldosteronism. The first step of this investigation is to exclude the ingestion of liquorice, alkalis and diuretics. The second is to make sure that the treatment is compatible with the hormonal tests and that the natriuresis and kaliuresis are normal. The diagnosis then depends on an increased plasma or urinary concentration of aldosterone with a low plasma renin activity. The adenoma of Conn is present in 2/3 of cases and surgically curable, and should be distinguished from adrenal hyperplasia which is treatable with distal diuretics. This is a diagnosis which requires computerised tomography or, when inconclusive, demonstration of unilateral secretion of aldosterone. Adrenalectomy, usually by coelioscopy, is indicated in Conn's adenoma when the patient is young and the hypertension severe or recent. Surgical abstention is strongly advised in cases of adrenal hyperplasia.

Two evolutionarily closely related ABC transporters mediate the uptake of choline for synthesis of the osmoprotectant glycine betaine in Bacillus subtilis.

Biosynthesis of the compatible solute glycine betaine in Bacillus subtilis confers a considerable degree of osmotic tolerance and proceeds via a two-step oxidation process of choline, with glycine betaine aldehyde as the intermediate. We have exploited the sensitivity of B. subtilis strains defective in glycine betaine production against glycine betaine aldehyde to select for mutants resistant to this toxic intermediate. These strains were also defective in choline uptake, and genetic analysis proved that two mutations affecting different genetic loci (opuB and opuC) were required for these phenotypes. Molecular analysis allowed us to demonstrate that the opuB and opuC operons each encode a binding protein-dependent ABC transport system that consists of four components. The presumed binding proteins of both ABC transporters were shown to be lipoproteins. Kinetic analysis of [14C]-choline uptake via OpuB (K(m) = 1 microM; Vmax = 21 nmol min-1 mg-1 protein) and OpuC (K(m) = 38 microM; Vmax = 75 nmol min-1 mg-1 protein) revealed that each of these ABC transporters exhibits high affinity and substantial transport capacity. Western blotting experiments with a polyclonal antiserum cross-reacting with the presumed substrate-binding proteins from both the OpuB and OpuC transporter suggested that the expression of the opuB and opuC operons is regulated in response to increasing osmolality of the growth medium. Primer extension analysis confirmed the osmotic control of opuB and allowed the identification of the promoter of this operon. The opuB and opuC operons are located close to each other on the B. subtilis chromosome, and their high sequence identity strongly suggests that these systems have evolved from a duplication event of a primordial gene cluster. Despite the close relatedness of OpuB and OpuC, these systems exhibit a striking difference in substrate specificity for osmoprotectants that would not have been predicted readily for such closely related ABC transporters.

[Fibromuscular dysplasia of the renal arteries]. / La dysplasie fibromusculaire des artères rénales.

Fibromuscular dysplasia is a non-atherosclerotic, non-inflammatory vascular disease that primary involves medium-sized and small arteries, most commonly the renal and carotid arteries. Dysplasic stenoses can be classified by angiography into three main subtypes, multifocal (multiple contiguous stenoses with the "string of beads" appearance), unifocal (single stenosis in a given renal artery), or tubular. The multifocal subtype is the most frequent and is usually associated with medial dysplasia, whereas unifocal and tubular stenoses are associated with intimal and perimedial dysplasia, respectively. Renovascular hypertension, mainly in women aged 30 to 50 years, is the most common manifestation of renal artery fibromuscular dysplasia. Its prevalence in hypertensive patients is estimated to less than 1 percent. The true prevalence of the disease is probably higher, however, because many cases can go undetected in normotensive or asymptomatic hypertensive patients. The first line treatment is percutaneous transluminal angioplasty that usually allows blood pressure improvement or normalization. Stenosis progression is slow and rarely leads to ischemic renal failure. Recognition of renal artery fibromuscular dysplasia should lead to screening for associated carotid artery lesions. Fibromuscular dysplasia can be a familial disease.

A genetic analysis of PAX3-FKHR, the oncogene of alveolar rhabdomyosarcoma.

The PAX3-FKHR fusion protein of human alveolar rhabdomyosarcoma consists of the DNA-binding domains of PAX3 and the transcriptional activation domain of FKHR. It induces oncogenic transformation in cultures of chicken embryo fibroblasts (CEFs). PAX3-FKHR-transformed CEFs have been kept in continuous culture for more than 1 year; when quiescent, portions of the cultures differentiate into several distinct cell types. Deletion analysis suggests that both DNA binding and transcriptional activation are required for the induction of the PAX3-FKHR-transformed cellular phenotype. Mutant PAX3-FKHR proteins with reduced DNA binding or transactivation induce altered cellular morphologies and growth behavior distinct from that of CEFs expressing wild-type PAX3-FKHR. Mutant proteins that completely lack DNA binding or transactivation potential fail to transform.

Uptake and synthesis of compatible solutes as microbial stress responses to high-osmolality environments.

All microorganisms possess a positive turgor, and maintenance of this outward-directed pressure is essential since it is generally considered as the driving force for cell expansion. Exposure of microorganisms to high-osmolality environments triggers rapid fluxes of cell water along the osmotic gradient out of the cell, thus causing a reduction in turgor and dehydration of the cytoplasm. To counteract the outflow of water, microorganisms increase their intracellular solute pool by amassing large amounts of organic osmolytes, the so-called compatible solutes. These osmoprotectants are highly congruous with the physiology of the cell and comprise a limited number of substances including the disaccharide trehalose, the amino acid proline, and the trimethylammonium compound glycine betaine. The intracellular amassing of compatible solutes as an adaptive strategy to high-osmolality environments is evolutionarily well-conserved in Bacteria, Archaea, and Eukarya. Furthermore, the nature of the osmolytes that are accumulated during water stress is maintained across the kingdoms, reflecting fundamental constraints on the kind of solutes that are compatible with macromolecular and cellular functions. Generally, compatible solutes can be amassed by microorganisms through uptake and synthesis. Here we summarise the molecular mechanisms of compatible solute accumulation in Escherichia coli and Bacillus subtilis, model organisms for the gram-negative and gram-positive branches of bacteria.

[Genetic study of renal artery fibromuscular dysplasia]. / Etude génétique de la dysplasie fibromusculaire des artères rénales.

The aim of this study was to conduct a formal pedigree analysis of the involvement of the elastin gene in families. From 140 subjects with renal FMD documented on angiography, family cases with documented renal artery fibromuscular dysplasia (FMD) and to test pedigrees were constructed and familial cases defined by angiographic evidence of FMD in at least one sibling. Familial screening was made either by echodoppler for asymptomatic subjects or by digital intravenous angiography for hypertensive subjects. Linkage analysis at the elastin gene locus was performed in these families with two polymorphic markers: one diallelic RFLP located in exon 16 and one multiallelic CA repeat located in intron 17 of the elastin gene. Fourteen pedigrees (10%) were obtained including nine sibling pairs, four trios and one vertical transmission from a father to his daughter. Most affected subjects were females (84%) but familial cases were more frequently bilateral than sporadic cases (80% vs 49%, p = 0.07). Pedigrees analysis was compatible with an autosomal dominant mode of inheritance and suggested in these families an age and sex-dependent incomplete penetrance model. Linkage analysis resulted in a maximum two-point lod score of 0.06 at theta = 0.20 using the dinucleotide CA repeat. Analysis of the diallelic marker revealed similar frequencies in affected and non affected subjects. This study highlights the role of genetics factors in approximately 10% of FMD cases. The elastin gene does not seem to be involved in the pathogenesis of FMD.

Regulation of the Escherichia coli water channel gene aqpZ.

Osmotic movement of water across bacterial cell membranes is postulated to be a homeostatic mechanism for maintaining cell turgor. The molecular water transporter remained elusive until discovery of the Escherichia coli water channel, AqpZ, however the regulation of the aqpZ gene expression and physiological function of the AqpZ protein are unknown. Northern analysis revealed a transcript of 0.7 kb, confirming the monocistronic nature of aqpZ. Regulatory studies performed with an aqpZ::lacZ low copy plasmid demonstrate enhanced expression during mid-logarithmic growth, and expression of the gene is dependent upon the extracellular osmolality, which increased in hypoosmotic environments but strongly reduced in hyperosmolar NaCl or KCl. While disruption of the chromosomal aqpZ is not lethal for E. coli, the colonies of the aqpZ knockout mutant are smaller than those of the parental wild-type strain. When cocultured with parental wild-type E. coli, the aqpZ knockout mutant exhibits markedly reduced colony formation when grown at 39 degrees C. Similarly, the aqpZ knockout mutant also exhibits greatly reduced colony formation when grown at low osmolality, but this phenotype is reversed by overexpression of AqpZ protein. These results implicate AqpZ as a participant in the adaptive response of E. coli to hypoosmotic environments and indicate a requirement for AqpZ by rapidly growing cells.

The use of dose-intensified chemotherapy in the treatment of metastatic nonseminomatous testicular germ cell tumors. German Testicular Cancer Study Group.

With the use of a cisplatin-based chemotherapy, metastatic testicular cancer has become a model for a highly curable malignant disease. Current data show that 70% to 80% of patients with this disease will achieve long-term survival following cisplatin/etoposide/bleomycin therapy. The role of high-dose chemotherapy with autologous stem cell support is being investigated in metastatic germ cell cancer in attempts to improve outcome for patients whose disease relapses after standard-dose chemotherapy and for those who present initially with advanced metastatic disease. Prognostic categories for patients receiving high-dose salvage chemotherapy have recently been developed: cisplatin-refractory disease, beta-human chorionic gonadotropin values greater than 1,000 U/L, and primary mediastinal germ cell tumors are factors characterizing patients who will derive less benefit from high-dose chemotherapy than those with chemosensitive disease at relapse. While standard-dose salvage chemotherapy achieves only a 20% long-term survival rate, high-dose salvage chemotherapy may yield a cure rate of approximately 40%. A randomized study comparing high-dose therapy with conventional-dose therapy (IT94 coordinated by the European Group for Blood and Marrow Transplantation) in patients with relapsed disease is ongoing to substantiate this observation. The use of dose-intensive therapy as first-line treatment is currently being studied by several institutions. High-dose therapy may be better tolerated when used first line compared with its use in the salvage situation, and may also achieve a rapid initial cell kill before cytostatic drug resistance develops. The German Testicular Cancer Study Group has developed a sequential high-dose combination regimen of cisplatin/etoposide/ifosfamide given with granulocyte colony-stimulating factor and peripheral blood stem cell support for four cycles every 3 weeks. This ongoing study, started in 1990, had accrued 218 patients with advanced testicular germ cell tumors as of June 1997. Of 141 evaluable patients receiving dose levels 1 through 5, 82 (58%) have achieved complete remission with no evidence of disease and 32 (23%) have achieved partial remission with marker normalization. The early death rate was 8%. Overall and event-free survival rates at 2 years are 78% and 73%, respectively, with a projected 5-year overall survival rate of 74%. Despite favorable preliminary results, this approach cannot be considered standard treatment. Currently, high-dose chemotherapy with peripheral blood stem cell transplantation should be administered to patients with testicular cancer only within controlled clinical trials to allow long-term cure rates and treatment-related late side effects to be evaluated.

Lipoprotein from the osmoregulated ABC transport system OpuA of Bacillus subtilis: purification of the glycine betaine binding protein and characterization of a functional lipidless mutant.

The OpuA transport system of Bacillus subtilis functions as a high-affinity uptake system for the osmoprotectant glycine betaine. It is a member of the ABC transporter superfamily and consists of an ATPase (OpuAA), an integral membrane protein (OpuAB), and a hydrophilic polypeptide (OpuAC) that shows the signature sequence of lipoproteins (B. Kempf and E. Bremer, J. Biol. Chem. 270:16701-16713, 1995). The OpuAC protein might thus serve as an extracellular substrate binding protein anchored in the cytoplasmic membrane via a lipid modification at an amino-terminal cysteine residue. A malE-opuAC hybrid gene was constructed and used to purify a lipidless OpuAC protein. The purified protein bound radiolabeled glycine betaine avidly and exhibited a KD of 6 microM for this ligand, demonstrating that OpuAC indeed functions as the substrate binding protein for the B. subtilis OpuA system. We have selectively expressed the opuAC gene under T7 phi10 control in Escherichia coli and have demonstrated through its metabolic labeling with [3H]palmitic acid that OpuAC is a lipoprotein. A mutant expressing an OpuAC protein in which the amino-terminal cysteine residue was changed to an alanine (OpuAC-3) was constructed by oligonucleotide site-directed mutagenesis. The OpuAC-3 protein was not acylated by [3H]palmitic acid, and part of it was secreted into the periplasmic space of E. coli, where it could be released from the cells by cold osmotic shock. The opuAC-3 mutation was recombined into an otherwise wild-type opuA operon in the chromosome of B. subtilis. Unexpectedly, this mutant OpuAC system still functioned efficiently for glycine betaine acquisition in vivo under high-osmolarity growth conditions. In addition, the mutant OpuA transporter exhibited kinetic parameters similar to that of the wild-type system. Our data suggest that the lipidless OpuAC-3 protein is held in the cytoplasmic membrane of B. subtilis via its uncleaved hydrophobic signal peptide.

The aquaporin-Z water channel gene of Escherichia coli: structure, organization and phylogeny.

Aquaporin water channel proteins are found throughout the plant and animal kingdoms, but the first prokaryotic water channel gene, aqpZ, was only recently identified in wild type Escherichia coli (Calamita G et al (1995) J Biol Chem 270, 29063-29066). Here we define the organization of aqpZ in E coli, produce the AqpZ protein and compare the AqpZ phylogeny to that of some known bacterial homologs. Physical mapping and sequence analyses confirmed the location of aqpZ at minute 19.7 on the E coli chromosome where it is transcribed counterclockwise. The monocistronic nature of aqpZ was clearly indicated by the structural organization of its surrounding genes, ybjD and ybjE' and by the presence of a typical Rho-independent transcriptional terminator following the aqpZ stop codon. Computer sequence analysis indicated the -35/-10 region located 72 bases upstream of the aqpZ start codon as the most likely aqpZ promoter. A series of potential cis-regulatory elements were found in the 400 bp region preceding the aqpZ ORF. The AqpZ protein, produced under T7 phi 10 control, showed a size of about 20 kDa by SDS-PAGE. Striking similarities were found between the E coli aqpZ and a gene included in the genome of the cyanobacterium Synechocystis sp PCC6803, a species permanently living a fresh water. These results may represent a fundamental step to characterize the regulation and the physiological features of the AqpZ water channel in prokaryotes.

Osmostress response in Bacillus subtilis: characterization of a proline uptake system (OpuE) regulated by high osmolarity and the alternative transcription factor sigma B.

Exogenously provided proline has been shown to serve as an osmoprotectant in Bacillus subtilis. Uptake of proline is under osmotic control and functions independently of the known transport systems for the osmoprotectant glycine betaine. We cloned the structural gene (opuE) for this proline transport system and constructed a chromosomal opuE mutant by marker replacement. The resulting B. subtilis strain was entirely deficient in osmoregulated proline transport activity and was no longer protected by exogenously provided proline, attesting to the central importance of OpuE for proline uptake in high-osmolarity environments. The transport characteristics and growth properties of the opuE mutant revealed the presence of a second proline transport activity in B. subtilis. DNA sequence analysis of the opuE region showed that the OpuE transporter (492 residues) consists of a single integral membrane protein. Database searches indicated that OpuE is a member of the sodium/solute symporter family, comprising proteins from both prokaryotes and eukaryotes that obligatorily couple substrate uptake to Na+ symport. The highest similarity was detected to the PutP proline permeases, which are used in Escherichia coli, Salmonella typhimurium and Staphylococcus aureus for the acquisition of proline as a carbon and nitrogen source, but not for osmoprotective purposes. An elevation of the osmolarity of the growth medium by either ionic or non-ionic osmolytes resulted in a strong increase in the OpuE-mediated proline uptake. This osmoregulated proline transport activity was entirely dependent on de novo protein synthesis, suggesting a transcriptional control mechanism. Primer extension analysis revealed the presence of two osmoregulated and tightly spaced opuE promoters. The activity of one of these promoters was dependent on sigma A and the second promoter was controlled by the general stress transcription factor sigma B.