The actinomycin biosynthetic gene cluster of Streptomyces chrysomallus: a genetic hall of mirrors for synthesis of a molecule with mirror symmetry.

A gene cluster was identified which contains genes involved in the biosynthesis of actinomycin encompassing 50 kb of contiguous DNA on the chromosome of Streptomyces chrysomallus. It contains 28 genes with biosynthetic functions and is bordered on both sides by IS elements. Unprecedentedly, the cluster consists of two large inverted repeats of 11 and 13 genes, respectively, with four nonribosomal peptide synthetase genes in the middle.

Functional cross-talk between fatty acid synthesis and nonribosomal peptide synthesis in quinoxaline antibiotic-producing streptomycetes.

Quinoxaline antibiotics are chromopeptide lactones embracing the two families of triostins and quinomycins, each having characteristic sulfur-containing cross-bridges. Interest in these compounds stems from their antineoplastic activities and their specific binding to DNA via bifunctional intercalation of the twin chromophores represented by quinoxaline-2-carboxylic acid (QA). Enzymatic analysis of triostin A-producing Streptomyces triostinicus and quinomycin A-producing Streptomyces echinatus revealed four nonribosomal peptide synthetase modules for the assembly of the quinoxalinoyl tetrapeptide backbone of the quinoxaline antibiotics.

Functional expression of the ectoine hydroxylase gene (thpD) from Streptomyces chrysomallus in Halomonas elongata.

The formation of hydroxyectoine in the industrial ectoine producer Halomonas elongata was improved by the heterologous expression of the ectoine hydroxylase gene, thpD, from Streptomyces chrysomallus. The efficient conversion of ectoine to hydroxyectoine was achieved by the concerted regulation of thpD by the H. elongata ectA promoter.

Combinatorial biosynthesis of non-ribosomal peptides.

Non-ribosomal peptide synthetases (NRPS) are modular assembly lines catalysing the synthesis of many small peptides in microbes. Genetic replacements of domains or modules in NRPS encoded by gene clusters in Bacillus sp. with corresponding domains or modules from foreign NRPS have led in several cases to the in vivo synthesis of peptides with predicted amino acid substitutions.

Nonribosomal biosynthesis of microbial chromopeptides.

Nonribosomal chromopeptides and mixed chromopeptide-polyketides contain aromatic or heteroaromatic side groups which are important recognition elements for interaction with cellular targets such as DNA and proteins, resulting in the biological activities of these natural products. In the chromopeptide lactones and arylpeptide-siderophores from bacteria, the chromophore moiety--an aryl carboxylate amidated to the peptide chain--constitutes the formal amino terminus and is the starter residue of peptide assembly. Common to many arylpeptide systems is the activation by stand-alone adenylation domains and loading of the starter to discrete aryl carrier proteins (ArCPs) or ArCP domains which interact with the modules of the respective nonribosomal peptide synthetase (NRPS), assembling the next residues of the chain.

Expression and rapid one-step purification of biologically active His-tagged factor C by Ni(2+) affinity column chromatography.

Factor C is an unusual extracellular protein capable of inducing cytodifferentiation in certain Streptomyces strains. The protein is produced by Streptomyces griseus 45H at such a low amount that the study of its mode of action was hindered by the shortage of purified protein. We report here the expression of C-terminally hexa-His-tagged factor C in Streptomyces lividans and Escherichia coli.

Construction and in vitro analysis of a new bi-modular polypeptide synthetase for synthesis of N-methylated acyl peptides.

Background: Many active peptides are synthesized by nonribosomal peptide synthetases (NRPSs), large multimodular enzymes. Each module incorporates one amino acid, and is composed of two domains: an activation domain that activates the substrate amino acid and a condensation domain for peptide-bond formation. Activation domains sometimes contain additional activities (e.

Transcriptional analysis of the cyclophilin A gene (cypA) of Streptomyces chrysomallus.

Streptomyces chrysomallus produces a 17.5-kDa cyclophilin (CypA) as a major cytosolic protein. Northern blotting of total RNA from S.

Molecular characterization of the genes of actinomycin synthetase I and of a 4-methyl-3-hydroxyanthranilic acid carrier protein involved in the assembly of the acylpeptide chain of actinomycin in Streptomyces.

Actinomycin synthetase I (ACMS I) activates 4-methyl-3-hydroxyanthranilic acid, the precursor of the chromophoric moiety of the actinomycin, as adenylate. The gene acmA of ACMS I was identified upstream of the genes acmB and acmC encoding the two peptide synthetases ACMS II and ACMS III, respectively, which assemble the pentapeptide lactone rings of the antibiotic. Sequence analysis and expression of acmA in Streptomyces lividans as enzymatically active hexa-His-fusion confirmed the acmA gene product to be ACMS I.

Structural elements of the Streptomyces oriC region and their interactions with the DnaA protein.

Streptomycetes differ from other prokaryotic organisms in their mycelial life cycle and in possessing a large, linear, GC-rich chromosome. To deduce structural features of the Streptomyces origin of chromosomal replication, the oriC sequences of three Streptomyces species (S. antibioticus, S.

Molecular cloning of the actinomycin synthetase gene cluster from Streptomyces chrysomallus and functional heterologous expression of the gene encoding actinomycin synthetase II.

The actinomycin synthetases ACMS I, II, and III catalyze the assembly of the acyl peptide lactone precursor of actinomycin by a nonribosomal mechanism. We have cloned the genes of ACMS I (acmA) and ACMS II (acmB) by hybridization screening of a cosmid library of Streptomyces chrysomallus DNA with synthetic oligonucleotides derived from peptide sequences of the two enzymes. Their genes were found to be closely linked and are arranged in opposite orientations.

Filament-specific expression of a cellulase gene in the dimorphic fungus Ustilago maydis.

The phytopathogenic fungus Ustilago maydis exists in a yeast-like haploid form and as a filamentous dikaryon. Only the dikaryon can infect corn plants. We have isolated a gene, egl1, that is not expressed in haploid cells but strongly induced in the filament.

Control of mating and development in Ustilago maydis.

In Ustilago maydis the a and b mating type loci control pathogenicity as well as sexual development. We review the function of these loci in controlling the cell fusion step, the switch from yeast-like to filamentous growth and subsequent pathogenic development. Our special emphasis will be the role of pheromones and pheromone signaling in these processes.

[Medical peculiarities and social effects of accidents with motorcycles].

During the period 1976 until 1982, 133 accident patients with two-cycle motor vehicles were treated at the traumatological Department of the Dr. Horst Schmidt Hospital. 80% of those patients were below or 21 years of age, 58.

[Conservative therapy of shoulder dislocation].

There is no undivided agreement in how long a shoulder ought to be fixed after a luxation. Having made a distinction between the terms of habitual and posttraumatic recidivous luxation of the shoulder, the results of a retrospective analysis of 118 luxations of the shoulder are shown, with 75 outpatients after a primary luxation. In most cases the fixation in the Desault-dressing was maintained for three to four days and was followed by early-functional physiotherapeutical after-treatment.

[Therapy of rupture of the great tubercle].

In most cases isolated avulsions of the great tubercle can be treated conservatively. 31 Patients suffering from an isolated avulsion of the great tubercle had to go through an after-examination. 30 of these patients were fixed on the conservative method for three to four days mostly, usually with a Desault-dressing, and, subsequently, they had to undergo a functional after-treatment, even if the dislocation of the fragment was partly more than 1 cm.

Measurement of knee-joint instabilities in the anterior-posterior plane.

The documentation of instabilities of the knee joint in sagittal direction by X-rays is usually inexact and incomplete by lack of rotational exertion. With a simple appliance instabilities of the knee joint in sagittal direction can be measured in mm within the examination. The difference between the injured and uninjured knee may show the importance of an instability of the knee joint.

[Clinical experiences with a new gel-like wound dressing after skin transplantation].

Free split skin grafting is now widely practised on a routine basis in accident surgery. All conventional wound dressing methods have considerable drawbacks, and this is one of the reasons why successful skin grafting is still an unsafe procedure even under the very best of conditions and quite often resembles an experiment more than a scientific procedure, with an unpredictable outcome. Today, however, we can command over a wound dressing, using the polyacrylamide agar hydrogel developed by the Max Planck Institute of Immunobiology at Freiburg and which is being marketed under the trade name of Geliperm.

[Malrotation following intramedullary nailing of the femur].

77 patients with previous intramedullary nailing of the femur underwent detailed clinical and roentgenographical examination designed to show the frequency and extent of malrotation following this type of osteosynthesis. In 29% of the cases, more than 10 degrees of torsion deviation was detected on the roentgenogram using the Rippstein technique. An average outward rotation of three degrees was found after nailing.

[Combined malleolar lesion in the growing skeleton].

Some examples are given in order to describe the combined lesion of the ankle joint in the growing skeleton after a supination trauma. This lesion in the growing skeleton is similar to the basic type A of luxation fractures according to Weber[4]: lateral ligament rupture or lysis of the fibular zone of bone growth, respectively, combined with fracture of the medial malleolus and involvement of the tibial zone of bone growth. In some cases, anteroposterior radiographs are necessary in order to establish a complete diagnosis.

[Therapy of hand joint fractures using the external fixator. Experiences - results].

In the treatment of multi-fragment fractures of the base of the radius plate osteosynthesis using the small-fragment instrument set is preferred to conservative treatment due to the superior results achieved. However, one still cannot dispense with an additional immobilization of the fracture in a plaster cast. The extension of intra-articular comminuted fractures of the base of the radius is a technically relatively simple procedure and does not require a supporting plaster cast.

[Advantages of early functional treatment of fractures of the thoracolumbar vertebrae without paresis compared with functional treatment after Magnus (author's transl)].

The results of two different method of conservative treatment of vertebral fractures are compared in Groups of each 60 patients. Group one was been treated by the early functional method, which is described, whereas group two was treated according to Magnus. The results of the first group were without prejudice to the results of the second group.