Differential proteomics highlights metabolic changes associated with n-hexadecane utilization in a Streptomyces coelicolor strain expressing Gordonia sp. SoCg n-alkane monooxigenase.

Abstract

Introduction: Alkanes are biodegraded to generate the corresponding primary alcohol trough alkane hydroxylases (AHs) consisting on an integral membrane alkane monooxygenase (AlkB) and two soluble proteins, rubredoxin and rubredoxin reductase. Recently, an alkB gene was reported to be involved in degradation of long chain n-alkanes in the actinobacterium Gordonia sp. SoCg. This gene was expressed in Streptomyces coelicolor M145 which is unable to degrade n-alkanes. Results: The engineered strain, M145-AH, can biotransform n-hexadecane into the corresponding 1-hexadecanol and it is able to grow on n-hexadecane as sole carbon source. Changes in global protein expression associated with n-hexadecane metabolism in M145-AH were studied using a differential proteomic approach. M145-AH was incubated in three different conditions using a mineral medium supplemented with hexadecane or glucose as the sole carbon source or without any carbon source, respectively. Total proteins, extracted from samples collected after 6, 24 and 48 h of incubation in the three conditions, were analyzed by 2D-Differential Gel Electrophoresis (2D-DIGE). Differentially abundant protein spots were identified by mass spectrometry. The expression profile of proteins involved in central carbon metabolism, amino acid and protein biosynthesis, fatty acid metabolism and respiration revealed a gradual metabolic adaptation to n-hexadecane utilization, which is similar to that of specialized alkane-degraders. Conclusion: Thus, the addition of the alkB gene confers to Streptomyces coelicolor the ability to use an insoluble recalcitrant contaminant as an usual carbon source. These data, expanding the knowledge on n-alkane bioconversion mechanisms in Gram-positive bacteria, provide new technological platforms for bioremediation studies and strategies.