title: Characterization of key triacylglycerol biosynthesis processes in rhodococci.
abstract: Oleaginous microorganisms have considerable potential for biofuel and commodity chemical production. Under nitrogen-limitation, Rhodococcus jostii RHA1 grown on benzoate, an analog of lignin depolymerization products, accumulated triacylglycerols (TAGs) to 55% of its dry weight during transition to stationary phase, with the predominant fatty acids being C16:0 and C17:0. Transcriptomic analyses of RHA1 grown under conditions of N-limitation and N-excess revealed 1,826 dysregulated genes. Genes whose transcripts were more abundant under N-limitation included those involved in ammonium assimilation, benzoate catabolism, fatty acid biosynthesis and the methylmalonyl-CoA pathway. Of the 16 atf genes potentially encoding diacylglycerol O-acyltransferases, atf8 transcripts were the most abundant during N-limitation (~50-fold more abundant than during N-excess). Consistent with Atf8 being a physiological determinant of TAG accumulation, a Δatf8 mutant accumulated 70% less TAG than wild-type RHA1 while atf8 overexpression increased TAG accumulation 20%. Genes encoding type-2 phosphatidic acid phosphatases were not significantly expressed. By contrast, three genes potentially encoding phosphatases of the haloacid dehalogenase superfamily and that cluster with, or are fused with other Kennedy pathway genes were dysregulated. Overall, these findings advance our understanding of TAG metabolism in mycolic acid-containing bacteria and provide a framework to engineer strains for increased TAG production.
authors.affiliation: Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada.
authors.forename: Sawsan
authors.initials: S
authors.lastname: Amara
authors.affiliation: Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Seghezzi
authors.affiliation: Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Otani
authors.affiliation: Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada.
authors.forename: Carlos
authors.initials: C
authors.lastname: Diaz-Salazar
authors.affiliation: Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada.
authors.forename: Jie
authors.initials: J
authors.lastname: Liu
authors.affiliation: Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada.
authors.forename: Lindsay D
authors.initials: LD
authors.lastname: Eltis
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics*; D053898:Biosynthetic Pathways; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D005810:Multigene Family; D009584:Nitrogen / Q000378:metabolism; D010711:Phosphatidate Phosphatase / Q000235:genetics; D012240:Rhodococcus / Q000235:genetics / Q000254:growth & development*; D014280:Triglycerides / Q000096:biosynthesis*
chemical_list: D001426:Bacterial Proteins; D014280:Triglycerides; C406242:phosphatidic acid phosphatase type 2; D010711:Phosphatidate Phosphatase; D009584:Nitrogen