title: Involvement of an alkane hydroxylase system of Gordonia sp. strain SoCg in degradation of solid n-alkanes.
abstract: 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.
authors.affiliation: Dipartimento di Biologia Cellulare e dello Sviluppo, Viale delle Scienze edif. 16, 90128 Palermo, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Lo Piccolo
authors.forename: Claudio
authors.initials: C
authors.lastname: De Pasquale
authors.forename: Roberta
authors.initials: R
authors.lastname: Fodale
authors.forename: Anna Maria
authors.initials: AM
authors.lastname: Puglia
authors.forename: Paola
authors.initials: P
authors.lastname: Quatrini
mesh_terms: D000473:Alkanes / Q000737:chemistry / Q000378:metabolism*; D002244:Carbon / Q000378:metabolism; D042926:Cytochrome P-450 CYP4A / Q000235:genetics* / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D005233:Fatty Alcohols / Q000378:metabolism; D008401:Gas Chromatography-Mass Spectrometry; D015870:Gene Expression; D033601:Gordonia Bacterium / Q000145:classification / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009247:NADH, NADPH Oxidoreductases / Q000235:genetics / Q000378:metabolism; D016133:Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012416:Rubredoxins / Q000235:genetics; D017422:Sequence Analysis, DNA; D017384:Sequence Deletion; D048372:Streptomyces coelicolor / Q000235:genetics / Q000378:metabolism
chemical_list: D000473:Alkanes; D005233:Fatty Alcohols; D012416:Rubredoxins; D002244:Carbon; C005031:cetyl alcohol; D042926:Cytochrome P-450 CYP4A; C023091:rubredoxin-NAD+ reductase; D009247:NADH, NADPH Oxidoreductases; C007932:n-hexadecane