Enzymes involved in lipid biosynthesis and metabolism play an important role in energy conversion and storage and in the function of structural components such as cell membranes. The fatty aldehyde dehydrogenase (FAldDH) plays a central function in the metabolism of lipid intermediates, oxidizing fatty aldehydes to the corresponding fatty acid and competing with pathways that would further reduce the fatty aldehydes to fatty alcohols or require the fatty aldehydes to produce alkanes. In this report, the genes for four putative FAldDH enzymes from Marinobacter aquaeolei VT8 and an additional enzyme from Acinetobacter baylyi were heterologously expressed in Escherichia coli and shown to display FAldDH activity. Five enzymes (Maqu_0438, Maqu_3316, Maqu_3410, Maqu_3572, and the enzyme reported under RefSeq accession no. WP_004927398) were found to act on aldehydes ranging from acetaldehyde to hexadecanal and also acted on the unsaturated long-chain palmitoleyl and oleyl aldehydes. A comparison of the specificities of these enzymes with various aldehydes is presented. Crystallization trials yielded diffraction-quality crystals of one particular FAldDH (Maqu_3316) from M. aquaeolei VT8. Crystals were independently treated with both the NAD+ cofactor and the aldehyde substrate decanal, revealing specific details of the likely substrate binding pocket for this class of enzymes. A likely model for how catalysis by the enzyme is accomplished is also provided.
Bibliographical noteFunding Information:
We thank Nagendra Palani for assistance in constructing plasmid pETMFA. We thank Chris Rothstein and Zeyuan Wu for assistance in early characterization of the Maqu_3410 enzyme. This work was supported by grants from the National Science Foundation to B.M.B. (award no. 0968781 and CBET-1437758) and C.J.D. (CHE-1151547) and from the National Institutes of Health to H.A. (NIGMS R35-GM118047). Further support was provided to B.M.B. through generous startup funds through the University of Minnesota. This work is based upon research conducted at the Northeastern Collaborative Access Team beamlines, which are funded by the U.S. National Institutes of Health (NIGMS P41-GM103403). The Pilatus 6M detector on the 24-ID-C beamline is funded by an NIH-ORIP HEI grant (S10 RR029205). This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under contract no. DE-AC02-06CH11357.
© 2017 American Society for Microbiology.
- Lipid biosynthesis
- Wax ester