Search

Researchers describe the gene complex that codes for protocatechuate 3,4-dioxygenase in Streptomyces sp. strain 2065. Protocatechuate is one of the branches of the beta-ketoadipate pathway, which is widely conserved among diverse soil microorganisms.

The function of jadl as an enzyme that facilitates the cyclization of decapolyketides to form the angluyclinone rabelomycin and 4-hydroxy-12bH-12-deoxyrabelomycin has been investigated. The results showed that the enzymes for the minimal jad PKS and minimal tcm PKS have similar functions and are exchangeable. However, the cyclase genes from the tcm and JAD biosynthetic pathways do not function when combined with the minimal PKS genes of the other clusters.

A Streptomyces lividans enzyme inactivates the peptidolactone antibiotic etamycin, by an elimination reaction involving ring opening. The enzyme catalyzes lactone ring cleavage to form a linear dehydrobutyrine peptide. The peptide does not incorporate water and its mass is the same as that of etamycin. The reaction of etamycin in NaOH gives a product formed by lactone bond hydrolysis and another product similar to that formed by the enzyme reaction. Spectroscopic studies show that the inactivation is due to an elimination rather than a hydrolysis reaction.

The genomic DNA libraries of S. venezuelae and a mutant strain are hybridized with a synthetic oligonucleotide. The bromoperoxidase-catalase gene in Streptomyces venezuelae is sequenced and cloned. Analysis of the nucleotide sequences shows no differences in the sequences of the gene and the synthetic oligonucleotide. This indicates that the gene's catalase activity governs its role in S. venezuelae.

The region of the Streptomyces venezuelae ISP5230 chromosome immediately downstream of the polyketide synthase gene cluster is investigated by cloning and sequence analyzing a fragment of the strain's DNA insert. Results indicate that the region encodes an oxygenase involved in opening ring B of an angucycline likely to be a biosynthetic intermediate. Jadomycins are formed when isoleucin molecules are injected into the site.

Disturbance of the nucleotide sequence of the putative Streptomyces venezuelae repressor gene (jadR2), by the insertion of an apramycin resistance gene at an internal MluI site, and replacement of the chromosomal gene resulted into mutants that can produce the antibiotic jadomycin B without exposing them to heat shock or toxic concentrations of ethanol. This means that expression of the jadomycin B biosynthesis genes are controlled by jadR2.

A lambda replacement vector enables cloning of hybridizing fragments in the DNA of Streptomyces venezuelae ISP5230. Sequence analysis of the fragments reveals the presence of five open reading frames (ORFs). Three of the ORFs suppress jadomycin B biosynthesis, as revealed by integration of a plasmid containing the three ORFs into the chromosomal DNA. The polypeptide products of these ORFs are similar to those of Streptomycete type-II polypeptide synthases.

Abstract Background Clostridium thermocellum is a Gram-positive thermophilic anaerobic bacterium with the unusual capacity to convert cellulosic biomass into ethanol and hydrogen. Identification and characterization of protein complexes in C. thermocellum are important toward understanding its metabolism and physiology. Results A two dimensional blue native/SDS-PAGE procedure was developed to separate membrane protein complexes of C. thermocellum. Proteins spots were identified by MALDI-TOF/TOF Mass spectrometry. 24 proteins were identified representing 13 distinct protein complexes, including several putative intact complexes. Interestingly, subunits of both the F1-F0-ATP synthase and the V1-V0-ATP synthase were detected in the membrane sample, indicating C. thermocellum may use alternative mechanisms for ATP generation. Conclusion Two dimensional blue native/SDS-PAGE was used to detect membrane protein complexes in C. thermocellum. More than a dozen putative protein complexes were identified, revealing the simultaneous expression of two sets of ATP synthase. The protocol developed in this work paves the way for further functional characterization of these protein complexes.

A study was conducted, with nuclear magnetic resonance (NMR) analysis data, to investigate the structure of jadomycin B and the production of profile of S. venezuelae ISP5230. The result revealed that the jadomycin B appears as an inseparable diastereomeric mixture with 67% 3a-S and 33% 3a-R configuration.

In this article, four novel substrates with long halftime have been designed and synthesized successfully for lux AB bacterial bioluminescence. After in vitro and in vivo biological evaluation, these molecules can emit obvious bioluminescence emission with known bacterial luciferase, thus indicating a new promising approach to developing the bacterial bioluminescent system. [ABSTRACT FROM AUTHOR]