title: Unraveling Cholesterol Catabolism inMycobacterium tuberculosis: ChsE4-ChsE5 α2β2Acyl-CoA Dehydrogenase Initiates β-Oxidation of 3-Oxo-cholest-4-en-26-oyl CoA.
abstract: The metabolism of host cholesterol byMycobacterium tuberculosis(Mtb) is an important factor for both its virulence and pathogenesis, although how and why cholesterol metabolism is required is not fully understood.Mtbuses a unique set of catabolic enzymes that are homologous to those required for classical β-oxidation of fatty acids but are specific for steroid-derived substrates. Here, we identify and assign the substrate specificities of two of these enzymes, ChsE4-ChsE5 (Rv3504-Rv3505) and ChsE3 (Rv3573c), that carry out cholesterol side chain oxidation inMtb.Steady-state assays demonstrate that ChsE4-ChsE5 preferentially catalyzes the oxidation of 3-oxo-cholest-4-en-26-oyl CoA in the first cycle of cholesterol side chain β-oxidation that ultimately yields propionyl-CoA, whereas ChsE3 specifically catalyzes the oxidation of 3-oxo-chol-4-en-24-oyl CoA in the second cycle of β-oxidation that generates acetyl-CoA. However, ChsE4-ChsE5 can catalyze the oxidation of 3-oxo-chol-4-en-24-oyl CoA as well as 3-oxo-4-pregnene-20-carboxyl-CoA. The functional redundancy of ChsE4-ChsE5 explains the in vivo phenotype of theigrknockout strain ofMycobacterium tuberculosis; the loss of ChsE1-ChsE2 can be compensated for by ChsE4-ChsE5 during the chronic phase of infection. The X-ray crystallographic structure of ChsE4-ChsE5 was determined to a resolution of 2.0 Å and represents the first high-resolution structure of a heterotetrameric acyl-CoA dehydrogenase (ACAD). Unlike typical homotetrameric ACADs that bind four flavin adenine dinucleotide (FAD) cofactors, ChsE4-ChsE5 binds one FAD at each dimer interface, resulting in only two substrate-binding sites rather than the classical four active sites. A comparison of the ChsE4-ChsE5 substrate-binding site to those of known mammalian ACADs reveals an enlarged binding cavity that accommodates steroid substrates and highlights novel prospects for designing inhibitors against the committed β-oxidation step in the first cycle of cholesterol side chain degradation byMtb.
authors.affiliation: Department of Chemistry, Department of Pharmacological Sciences, and Biochemistry and Structural Biology Graduate Program, Stony Brook University , Stony Brook, New York 11794, United States.
authors.forename: Meng
authors.initials: M
authors.lastname: Yang
authors.affiliation: Department of Chemistry, Department of Pharmacological Sciences, and Biochemistry and Structural Biology Graduate Program, Stony Brook University , Stony Brook, New York 11794, United States.
authors.forename: Rui
authors.initials: R
authors.lastname: Lu
authors.affiliation: Department of Chemistry, Department of Pharmacological Sciences, and Biochemistry and Structural Biology Graduate Program, Stony Brook University , Stony Brook, New York 11794, United States.
authors.forename: Kip E
authors.initials: KE
authors.lastname: Guja
authors.affiliation: Department of Chemistry, Department of Pharmacological Sciences, and Biochemistry and Structural Biology Graduate Program, Stony Brook University , Stony Brook, New York 11794, United States.
authors.forename: Matthew F
authors.initials: MF
authors.lastname: Wipperman
authors.affiliation: Department of Chemistry, Department of Pharmacological Sciences, and Biochemistry and Structural Biology Graduate Program, Stony Brook University , Stony Brook, New York 11794, United States.
authors.forename: Johnna R
authors.initials: JR
authors.lastname: St Clair
authors.affiliation: Department of Chemistry, Department of Pharmacological Sciences, and Biochemistry and Structural Biology Graduate Program, Stony Brook University , Stony Brook, New York 11794, United States.
authors.forename: Amber C
authors.initials: AC
authors.lastname: Bonds
authors.affiliation: Department of Chemistry, Department of Pharmacological Sciences, and Biochemistry and Structural Biology Graduate Program, Stony Brook University , Stony Brook, New York 11794, United States.
authors.forename: Miguel
authors.initials: M
authors.lastname: Garcia-Diaz
authors.affiliation: Department of Chemistry, Department of Pharmacological Sciences, and Biochemistry and Structural Biology Graduate Program, Stony Brook University , Stony Brook, New York 11794, United States.
authors.forename: Nicole S
authors.initials: NS
authors.lastname: Sampson
keywords: 17-hydroxy-3-oxo-23,24-bisnorchol-4-en-22-oyl-CoA; 3-oxo-23,24-bisnorchol-4,17-dien-22-oyl-CoA; 3-oxo-23,24-bisnorchol-4-en-22-oyl-CoA; cholesterol metabolism; drug target; tuberculosis