Ribostamycin production by a mutant of butirosin producing bacteria

A hybrid strategy using global analysis of oxidized fatty acids and bioconversion by Bacillus circulans

RATIONALE

Targeted oxidized fatty acid analysis has been widely used to understand the roles of fatty acids in the development of diseases. However, because of the extensive structural diversity of fatty acids, it is considered that unknown lipid metabolites will remain undetected. Here, to discover and identify unknown lipid metabolites in biological samples, a global analytical system and a method of synthesizing lipid standards were investigated.

METHODS

Oxidized fatty acids in mouse lung tissues were extracted using mixed-mode spin columns. Separation was achieved via ultra-high-performance liquid chromatography, mass spectrometric (MS) analysis was conducted in full scan mode using a Q Exactive Plus instrument equipped with an electrospray ionization probe, and structure analysis was carried out by high-resolution data-dependent tandem mass spectrometry (dd-MS(2)). In addition, lipid standards, which are not commercially available, were synthesized by bioconversion using Bacillus circulans.

RESULTS

Oxidized fatty acids in mouse lung tissues were analyzed by high-resolution accurate-mass analysis, and multiple unknown molecules were discovered and tentatively identified using high-resolution dd-MS(2). Among these molecules, 21-hydroxydocosahexaenoic acid (21-HDoHE) and 22-HDoHE, which are not commercially available, were synthesized by bioconversion. By comparing the exact masses, retention times, and characteristic fragment ions of the synthesized standards, 21-HDoHE and 22-HDoHE were definitively identified in the mouse lung tissue.

CONCLUSIONS

Our strategy of global analysis and bioconversion can be used for the discovery and identification of unknown lipid molecules.

Biosynthesis of aminocyclitol-aminoglycoside antibiotics and related compounds

This review covers the biosynthesis of aminocyclitol-aminoglycoside antibiotics and related compounds, particularly from the molecular genetic perspectives. 195 references are cited.

Biosynthesis of butirosin in Bacillus circulans NRRL B3312: identification by sequence analysis and insertional mutagenesis of the butB gene involved in antibiotic production

As an approach to an analysis of the biosynthesis of the aminoglycoside antibiotic butirosin (But), we investigated the chromosomal regions flanking the ButR gene (aphA4/butA) of Bacillus circulans NRRL-B3312, and have identified, by nucleotide sequence analysis, a large open reading frame (ORF; ButB) upstream from the ButR gene. Hybridization was detected between butB and chromosomal DNA from other Bacillaceae that produce But-like compounds (but not from non-producers). Interruption of this sequence by insertion of an erythromycin-resistance-encoding gene (erm) at either of two distinct sites eliminated the production (biosynthesis or export) of But, thus indicating a role for butB in antibiotic production. Gene butB is transcribed in the same direction as butA and encodes a protein of 1616 amino acid (aa) residues with a 30-aa N-terminal signal peptide. Comparison of the sequence for the translation product (ButB) with the aa compositions and sequences of known bacterial surface proteins, such as S-layer proteins, suggests that this protein is cell-wall associated. It is proposed that ButB plays a role in the export of But from the producing organism.