Analysis of a gene cluster from S. longisporoflavus potentially involved in tetronasin biosynthesis.
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Amino Acid Sequence↗
Biomedical subjects
J Cortes
Publications and source records attributed to J Cortes.
6-Deoxyerythronolide-B synthase 2 from Saccharopolyspora erythraea. Cloning of the structural gene, sequence analysis and inferred domain structure of the multifunctional enzyme.
Sequencing of the eryA region of the erythromycin biosynthetic gene cluster from Saccharopolyspora erythraea has revealed another structural gene (ORF B), in addition to the previously characterised ORF A, which appears to encode a component of 6-deoxyerythronolide-B synthase, the enzyme that catalyses the first stage in the biosynthesis of the polyketide antibiotic erythromycin A. The nucleotide sequence of ORF B, which lies immediately adjacent to ORF A, has been determined. The predicted gene product of ORF B is a polypeptide of 374417 Da (3568 amino acids), which is highly similar to the product of ORF A and which likewise contains a number of separate domains, each with substantial amino acid sequence similarity to components of known fatty-acid synthases and polyketide synthases. The order of the predicted active sites along the chain from the N-terminus is 3-oxoacyl-synthase--acyltransferase--acyl-carrier-protein-- 3-oxoacyl-synthase--acyltransferase--dehydratase--enoylreductase-- oxoreductase--acyl-carrier-protein. The position of the dehydratase active site has been pinpointed for the first time for any polyketide synthase or vertebrate fatty-acid synthase. The predicted domain structure of 6-deoxyerythronolide-B synthase is strikingly similar to that previously established for vertebrate fatty-acid synthases. This analysis of the sequence supports the view that the erythromycin-producing polyketide synthase contains three multienzyme polypeptides, each of which accomplishes two successive cycles of polyketide chain extension. In this scheme, the role of the ORF B gene product is to accomplish extension cycles 3 and 4.
Amino Acid Sequence↗
Cloning and sequence analysis of genes involved in erythromycin biosynthesis in Saccharopolyspora erythraea: sequence similarities between EryG and a family of S-adenosylmethionine-dependent methyltransferases.
The gene cluster (ery) responsible for production of the macrolide antibiotic erythromycin by Saccharopolyspora erythraea is also known to contain ermE, the gene conferring resistance to the antibiotic. The nucleotide sequence has been determined of a 4.5 kb portion of the biosynthetic gene cluster, from a region lying between 3.7 kb and 8.2 kb 3' of ermE. This has revealed the presence of four complete open reading frames, including the previously known ery gene eryG, which catalyses the last step in the biosynthetic pathway. Comparison of the amino acid sequence of EryG with the sequence of other S-adenosylmethionine (SAM)-dependent methyltransferases has revealed that one of the sequence motifs previously suggested to be part of the SAM-binding site is present not only in EryG but also in many other recently sequenced SAM-dependent methyltransferases. Previous genetic studies have shown that this region also contains gene(s) involved in hydroxylation of the intermediate 6-deoxyerythronolide B. One of the three other open reading frames (eryF) in fact shows very high sequence similarity to known cytochrome P450 hydroxylases. An adjacent gene (ORF5) shows a strikingly high degree of similarity to prokaryotic and eukaryotic acyltransferases and thioesterases.
Amino Acid Sequence↗
An unusually large multifunctional polypeptide in the erythromycin-producing polyketide synthase of Saccharopolyspora erythraea.
Erythromycin A, a clinically important polyketide antibiotic, is produced by the Gram-positive bacterium Saccharopolyspora erythraea. In an arrangement that seems to be generally true of antibiotic biosynthetic genes in Streptomyces and related bacteria like S. erythraea, the ery genes encoding the biosynthetic pathway to erythromycin are clustered around the gene (ermE) that confers self-resistance on S. erythraea. The aglycone core of erythromycin A is derived from one propionyl-CoA and six methylmalonyl-CoA units, which are incorporated head-to-tail into the growing polyketide chain, in a process similar to that of fatty-acid biosynthesis, to generate a macrolide intermediate, 6-deoxyerythronolide B. 6-Deoxyerythronolide B is converted into erythromycin A through the action of specific hydroxylases, glycosyltransferases and a methyltransferase. We report here the analysis of about 10 kilobases of DNA from S. erythraea, cloned by chromosome 'walking' outwards from the erythromycin-resistance determinant ermE, and previously shown to be essential for erythromycin biosynthesis. Partial sequencing of this region indicates that it encodes the synthase. Our results confirm this, and reveal a novel organization of the erythromycin-producing polyketide synthase, which provides further insight into the mechanism of chain assembly.
Amino Acid Sequence↗
Molecular characterization of a gene from Saccharopolyspora erythraea (Streptomyces erythraeus) which is involved in erythromycin biosynthesis.
A 7.3 kbp DNA fragment, encompassing the erythromycin (Em) resistance gene (ermE) and a portion of the gene cluster encoding the biosynthetic genes for erythromycin biosynthesis in Saccharopolyspora erythraea (formerly Streptomyces erythraeus) has been cloned in Streptomyces lividans using the plasmid vector pIJ702, and its nucleotide sequence has been determined using a modified dideoxy chain-termination procedure. In particular, we have examined the region immediately 5' of the resistance determinant, where the tandem promoters for ermE overlap the promoters for a divergently transcribed coding sequence (ORF). Disruption of this ORF using an integrational pIJ702-based plasmid vector gave mutants which were specifically blocked in erythromycin biosynthesis, and which accumulated 3-O-alpha-L-mycarosylerythronolide B: this behaviour is identical to that of previously described eryC1 mutants. The eryC1-gene product, a protein of subunit Mr 39,200, is therefore involved either as a structural or as a regulatory gene in the formation of the deoxyamino-sugar desosamine or in its attachment to the macrolide ring.
Amino Acid Sequence↗
Cloning, characterization, and heterologous expression of the Saccharopolyspora erythraea (Streptomyces erythraeus) gene encoding an EF-hand calcium-binding protein.
The regulatory effects of Ca2+ in eucaryotic cells are mostly mediated by a superfamily of Ca2+-binding proteins (CABs) that contain one or more characteristic Ca2+-binding structural motifs, referred to as EF hands. We have cloned and sequenced the structural gene for an authentic EF-hand CAB from the spore-forming gram-positive bacterium Saccharopolyspora erythraea (formerly Streptomyces erythraeus). When the gene was introduced into Streptomyces lividans on the high-copy plasmid vector pIJ702, CAB was found to be expressed at higher levels than in S. erythraea, with no apparent effects on either growth or sporulation. A more convenient expression system for CAB was obtained by introducing an NdeI site at the initiation codon by using oligonucleotide-directed mutagenesis and placing the gene in the expression vector pT7-7 in Escherichia coli. In this system, CAB was efficiently expressed at levels up to 20 to 30% of total cell protein. When purified to homogeneity from either E. coli or Streptomyces lividans, CAB was found to be identical to the protein previously obtained from S. erythraea.
Amino Acid Sequence↗
[Kawasaki's disease].
We described a case of Kawasaki's disease in a chilean girl, one year and 5 months old of age, who presented the oral characteristics, cutaneous and systemic manifestation of the condition, that is not very common for the dentist but that it is necessary to know due to the heart complications and the mortality associated with the disease, and it is necessary that the dentist recognize early this condition.
Dental Care for Persons with Disabilities↗
Second tumor in gynecological cancer.
We have searched the second tumor in a series of 695 women with gynecological cancer. We have determined with precision when the second tumor was diagnosed: during the first tumor staging (7 cases), during its treatment (3 cases) or in its follow-up (9 cases). We comment the clinical, diagnostic, histologic and prognostic circumstances of this women with multiple cancer.
Female↗
Danazol and its principal metabolites interfere with binding of testosterone, cortisol, and thyroxin by plasma proteins.
Danazol and its three principal metabolites (2-hydroxy-methylethisterone, 2-hydroxymethyl-1,2-dehydroethisterone, and ethisterone) competitively displace cortisol and testosterone from plasma proteins. This effect is in addition to the reported inhibition of the production of testosterone-binding globulin and thyroxin-binding globulin. We saw no competitive inhibition of thyroxin binding. Concentrations of total testosterone, total cortisol, and total thyroxin were low, whereas percentages of free testosterone, free cortisol, and free thyroxin were abnormally high in women being treated with danazol. Values for testosterone, cortisol, and thyroxin in danazol-treated patients should therefore be appropriately corrected before interpretation. Protein-binding assays for testosterone or cortisol that involve testosterone- or cortisol-binding globulin may be invalid in danazol-treated subjects because of the competitive binding of danazol and its metabolites to these proteins.
Adult↗
[Forward traction in Class III malocclusions. Design of the impression tray and a standard mask (author's transl)].
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Child↗
[Sciatic nerve block by the lateral route at the level of the popliteal fossa with 0.75% ropivacine: advantages of a more proximal approach].
OBJECTIVES: To assess the efficacy of a sciatic nerve block using a lateral approach 11 cm cephalad to the lateral femoral epicondyle for providing surgical anesthesia and postoperative analgesia in scheduled foot surgery (hallux valgus) after a single injection of 30 mL of 0.75% ropivacaine. METHODS: A block was performed in 30 patients using a point of puncture 11 cm cephalad to the most prominent point of the lateral femoral epicondyle in the groove between the biceps femoris and vastus lateralis muscles. Once the nerve had been located with a stimulator (2 Hz, 0.5 mA), 30 mL of 0.75% ropivacaine was injected. Data recorded were time until block, number of attempts, depth at which the nerve was found, sciatic nerve response obtained, and time until the sensory block was complete. We evaluated quality of anesthesia during surgery, duration of postoperative analgesia, and patient discomfort during performance of the block. RESULTS: Time required to perform the block was 4.3 +/- 1.2 minutes and only one puncture attempt was needed in 27 patients. The nerve was located at 5.5 +/- 0.4 cm, with response located in the common peroneal nerve in 18 patients and in the posterior tibial nerve in 12. The time needed to achieve a full sensory block was 19.3 +/- 5.1 minutes. Twenty-six patients (86%) were very satisfied with the anesthetic quality of the block, 2 were moderately satisfied, and 2 were dissatisfied. Postoperative analgesia lasted 19 +/- 3.4 hours. Four patients reported minimal discomfort during performance of the block. No complications were observed. CONCLUSIONS: The sciatic nerve block from a lateral approach 11 cm cephalad to the lateral femoral epidondyle is an appropriate anesthetic technique for foot surgery. It is safe, effective and easy to perform. Infusion of 30 mL of 0.75% ropivacaine provided adequate anesthesia and long-lasting postoperative analgesia for our patients.
Adult↗
[Edgewise arch. Mechanics for the treatment of Angle class I, II, and III].
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Adolescent↗
Effects of interferon-alpha therapy on lymphocyte subpopulations in patients with chronic myeloid leukemia.
The mechanism of action of interferon-alpha (IFN-A) in chronic myelogenous leukemia (CML) is not known, but some evidence points at the immune modulation properties of IFN-A. We conducted a prospective analysis on 49 patients with CML in chronic phase treated with IFN-A in order to identify the effect of therapy on different lymphocyte subpopulations as determined by flow cytometric quantification and whether this effect is associated with the response to IFN-A. The absolute number of lymphocytes was similar in all patients regardless of response to IFN-A. In patients achieving a complete cytogenetic response (CCGR) there was a rebound of the absolute count of CD3+, CD4+, CD8+, and CD19+ lymphocytes after discontinuation of therapy with IFN-A. Patients with resistant disease, as well as patients with hematologic response but no cytogenetic response, showed a lower absolute number of CD19+ cells than patients with any cytogenetic response. Patients who achieved a CCGR had a higher absolute number of CD56+ cells than patients with lesser response or no response to IFN-A, and this persisted after discontinuation of therapy. We conclude that an increase in absolute number of CD19+ and CD56+ lymphocytes is observed in CML patients achieving a CCGR with IFN-A compared to patients with lesser responses. These changes could have functional consequences in the control of the disease.
Adult↗