title: Structure, activity, and inhibition of the Carboxyltransferase β-subunit of acetyl coenzyme A carboxylase (AccD6) from Mycobacterium tuberculosis.
abstract: In Mycobacterium tuberculosis, the carboxylation of acetyl coenzyme A (acetyl-CoA) to produce malonyl-CoA, a building block in long-chain fatty acid biosynthesis, is catalyzed by two enzymes working sequentially: a biotin carboxylase (AccA) and a carboxyltransferase (AccD). While the exact roles of the three different biotin carboxylases (AccA1 to -3) and the six carboxyltransferases (AccD1 to -6) in M. tuberculosis are still not clear, AccD6 in complex with AccA3 can synthesize malonyl-CoA from acetyl-CoA. A series of 10 herbicides that target plant acetyl-CoA carboxylases (ACC) were tested for inhibition of AccD6 and for whole-cell activity against M. tuberculosis. From the tested herbicides, haloxyfop, an arylophenoxypropionate, showed in vitro inhibition of M. tuberculosis AccD6, with a 50% inhibitory concentration (IC50) of 21.4 ± 1 μM. Here, we report the crystal structures of M. tuberculosis AccD6 in the apo form (3.0 Å) and in complex with haloxyfop-R (2.3 Å). The structure of M. tuberculosis AccD6 in complex with haloxyfop-R shows two molecules of the inhibitor bound on each AccD6 subunit. These results indicate the potential for developing novel therapeutics for tuberculosis based on herbicides with low human toxicity.
authors.affiliation: Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, USA.
authors.forename: Manchi C M
authors.initials: MC
authors.lastname: Reddy
authors.affiliation: Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, USA.
authors.forename: Ardala
authors.initials: A
authors.lastname: Breda
authors.affiliation: Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, USA.
authors.forename: John B
authors.initials: JB
authors.lastname: Bruning
authors.affiliation: Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, USA.
authors.forename: Mukul
authors.initials: M
authors.lastname: Sherekar
authors.affiliation: Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, USA.
authors.forename: Spandana
authors.initials: S
authors.lastname: Valluru
authors.affiliation: Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, USA.
authors.forename: Cory
authors.initials: C
authors.lastname: Thurman
authors.affiliation: Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, USA.
authors.forename: Hannah
authors.initials: H
authors.lastname: Ehrenfeld
authors.affiliation: Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, USA sacchett@tamu.edu.
authors.forename: James C
authors.initials: JC
authors.lastname: Sacchettini
mesh_terms: D000103:Acetyl-CoA Carboxylase / Q000737:chemistry* / Q000378:metabolism*; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism*; D019878:Carboxyl and Carbamoyl Transferases / Q000737:chemistry* / Q000378:metabolism*; D018360:Crystallography, X-Ray; D004789:Enzyme Activation / Q000187:drug effects; D006540:Herbicides / Q000494:pharmacology; D008962:Models, Theoretical; D009169:Mycobacterium tuberculosis / Q000201:enzymology*; D011485:Protein Binding; D011725:Pyridines / Q000494:pharmacology
chemical_list: D001426:Bacterial Proteins; D006540:Herbicides; D011725:Pyridines; C054176:haloxyfop; D019878:Carboxyl and Carbamoyl Transferases; D000103:Acetyl-CoA Carboxylase
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