Enzymes involved in oxidation of long-chain n -alkanes are still not well known, especially those in Gram-positive bacteria. This work describes the alkane degradation system of the n -alkane degrader actinobacterium Gordonia sp. strain SoCg, which is able to grow on n -alkanes from dodecane (C ₁₂ ) to hexatriacontane (C ₃₆ ) as the sole C source. SoCg harbors in its chromosome a single alk locus carrying six open reading frames (ORFs), which shows 78 to 79% identity with the alkane hydroxylase (AH)-encoding systems of other alkane-degrading actinobacteria. Quantitative reverse transcription-PCR showed that the genes encoding AlkB (alkane 1-monooxygenase), RubA3 (rubredoxin), RubA4 (rubredoxin), and RubB (rubredoxin reductase) were induced by both n -hexadecane and n -triacontane, which were chosen as representative long-chain liquid and solid n -alkane molecules, respectively. Biotransformation of n -hexadecane into the corresponding 1-hexadecanol was detected by solid-phase microextraction coupled with gas chromatography-mass spectrometry (SPME/GC-MS) analysis. The Gordonia SoCg alkB was heterologously expressed in Escherichia coli BL21 and in Streptomyces coelicolor M145, and both hosts acquired the ability to transform n -hexadecane into 1-hexadecanol, but the corresponding long-chain alcohol was never detected on n -triacontane. However, the recombinant S. coelicolor M145-AH, expressing the Gordonia alkB gene, was able to grow on n -triacontane as the sole C source. A SoCg alkB disruption mutant that is completely unable to grow on n -triacontane was obtained, demonstrating the role of an AlkB-type AH system in degradation of solid n -alkanes.

The actinomycete Nonomuraea sp. strain ATCC 39727 produces the glycopeptide A40926, the precursor of the novel antibiotic dalbavancin. Previous studies have shown that phosphate limitation results in enhanced A40926 production. The A40926 biosynthetic gene ( dbv ) cluster, which consists of 37 genes, encodes two putative regulators, Dbv3 and Dbv4, as well as the response regulator (Dbv6) and the sensor-kinase (Dbv22) of a putative two-component system. Reverse transcription-PCR (RT-PCR) and real-time RT-PCR analysis revealed that the dbv14 - dbv8 and the dbv30 - dbv35 operons, as well as dbv4 , were negatively influenced by phosphate. Dbv4 shows a putative helix-turn-helix DNA-binding motif and shares sequence similarity with StrR, the transcriptional activator of streptomycin biosynthesis in Streptomyces griseus . Dbv4 was expressed in Escherichia coli as an N-terminal His ₆ -tagged protein. The purified protein bound the dbv14 and dbv30 upstream regions but not the region preceding dbv4 . Bbr, a Dbv4 ortholog from the gene cluster for the synthesis of the glycopeptide balhimycin, also bound to the dbv14 and dbv30 upstream regions, while Dbv4 bound appropriate regions from the balhimycin cluster. Our results provide new insights into the regulation of glycopeptide antibiotics, indicating that the phosphate-controlled regulator Dbv4 governs two key steps in A40926 biosynthesis: the biosynthesis of the nonproteinogenic amino acid 3,5-dihydroxyphenylglycine and critical tailoring reactions on the heptapeptide backbone.