Crystallization and preliminary X-ray diffraction studies of a complex of extracellular lipase from Streptomyces rimosus with the inhibitor 3,4-dichloroisocoumarin.

A recombinant lipase (triacylglycerol acylhydrolase; EC 3.1.1.3) from the bacterium Streptomyces rimosus was inhibited by the serine protease inhibitor 3,4-dichloroisocoumarin and crystallized by the hanging-drop vapour-diffusion method at 291 K. The crystals belonged to the monoclinic space group P2(1), with unit-cell parameters a = 38.1, b = 78.7, c = 56.6 Å, ß = 104.5° and probably two molecules in the asymmetric unit. Diffraction data were collected to 1.7 Å resolution using synchrotron radiation on the XRD beamline of the Elettra synchrotron, Trieste, Italy.

Genetics of Streptomyces rimosus, the oxytetracycline producer.

From a genetic standpoint, Streptomyces rimosus is arguably the best-characterized industrial streptomycete as the producer of oxytetracycline and other tetracycline antibiotics. Although resistance to these antibiotics has reduced their clinical use in recent years, tetracyclines have an increasing role in the treatment of emerging infections and noninfective diseases. Procedures for in vivo and in vitro genetic manipulations in S. rimosus have been developed since the 1950s and applied to study the genetic instability of S. rimosus strains and for the molecular cloning and characterization of genes involved in oxytetracycline biosynthesis. Recent advances in the methodology of genome sequencing bring the realistic prospect of obtaining the genome sequence of S. rimosus in the near term.

A novel streptomycete lipase: cloning, sequencing and high-level expression of the Streptomyces rimosus GDS(L)-lipase gene.

An extracellular lipase from Streptomyces rimosus R6-554W has been recently purified and biochemically characterized. In this report the cloning, sequencing, and high-level expression of its gene is described. The cloned DNA contained an ORF of 804 bp encoding a 268-amino-acid polypeptide with 34 amino acid residues at the amino terminus of the sequence that were not found in the mature protein. The theoretical molecular mass (24.172 kDa) deduced from the amino acid sequence of the mature enzyme was experimentally confirmed. This lipase showed no overall amino acid sequence similarity to other lipases in the databases. However, two hypothetical proteins, i. e. putative hydrolases, derived from the genome sequencing data of Streptomyces coelicolor A3(2), showed 66% and 33% identity. In addition, a significant similarity to esterases from Streptomyces diastatochromogenes and Aspergillus terreus was found. Sequence analysis revealed that our novel S. rimosus lipase containing a GDS(L)-like consensus motif belongs to family II of lipolytic enzymes, previously unrecognized in Streptomyces. When the lipase gene was expressed in a S. rimosus lipase-deficient strain harboring the lipase gene on a high-copy-number vector, lipase activity was 22-fold higher than in the original strain.

Structural characterization of extracellular lipase from Streptomyces rimosus: assignment of disulfide bridge pattern by mass spectrometry.

The cloning, sequencing and high-level expression of the gene encoding extracellular lipase from Streptomyces rimosus R6-554W have been recently described, and the primary structure of this gene product was deduced using a bioinformatic approach. In this study, capillary electrophoresis-on-the-chip and mass spectrometry were used to characterize native and overexpressed extracellular lipase protein from S. rimosus . The exact molecular mass of the wild-type and the overexpressed lipase, determined by matrix-assisted laser desorption/ionization (MALDI) mass spectrometry, were in excellent agreement (Deltam=0.11 Da and Deltam=0.26 Da, respectively) with a value of 24165.76 Da calculated from the structure deduced from the nucleotide sequence, considering the mature enzyme with all six cysteines forming disulfide bridges. The primary structure derived from the nucleotide sequence was completely verified using a combination of tryptic digestion and formic acid cleavage of the protein, followed by peptide mass fingerprinting. Selected peptides were further investigated by MALDI low-energy collision-induced dissociation hybrid tandem mass spectrometry, allowing the unambiguous determination of their predicted amino acid sequence. No post-translational modifications of mature S. rimosus lipase were detected. Comparison of the peptide mass fingerprints from the reduced and non-reduced overexpressed enzyme unequivocally revealed three intramolecular disulfide bonds with the following linkages: C27-C52, C93-C101 and C151-C198.