A Missense Mutation in the fabB (β-Ketoacyl-Acyl Carrier Protein Synthase I) Gene Confers Thiolactomycin Resistance to Escherichia coli

ABSTRACT Thiolactomycin (TLM) is an antibiotic that inhibits bacterial type II fatty acid synthesis at the condensing enzyme step, and β-ketoacyl-acyl carrier protein synthase I (FabB) is the relevant target in Escherichia coli. TLM resistance is associated with the upregulation of efflux pumps. Therefore, a tolC knockout mutant (strain ANS1) was constructed to eliminate the contribution of type I secretion systems to TLM resistance. Six independent TLM-resistant clones of strain ANS1 were isolated, and all possessed the same missense mutation in the fabB gene (T1168G) that directed the expression of a mutant protein, FabB(F390V). FabB(F390V) was resistant to TLM in vitro. Leucine is the only other amino acid found at position 390 in nature, and the Staphylococcus aureus FabF protein, which contains this substitution, was sensitive to TLM. Structural modeling predicted that the CG2 methyl group of the valine side chain interfered with the positioning of the C11 methyl on the isoprenoid side chain of TLM in the binary complex, whereas the absence of a bulky methyl group on the leucine side chain permitted TLM binding. These data illustrate that missense mutations that introduce valine at position 390 confer TLM resistance while maintaining the vital catalytic properties of FabB.

Download Full-text

Faculty Opinions recommendation of A missense mutation in the fabB (beta-ketoacyl-acyl carrier protein synthase I) gene confers tiolactomycin resistance to Escherichia coli.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1007252.85311 ◽

2002 ◽

Author(s):

Juan Luis Ramos

Keyword(s):

Escherichia Coli ◽

Missense Mutation ◽

Acyl Carrier Protein ◽

Carrier Protein ◽

I Gene

Download Full-text

Scavenging of Cytosolic Octanoic Acid by Mutant LplA Lipoate Ligases Allows Growth of Escherichia coli Strains Lacking the LipB Octanoyltransferase of Lipoic Acid Synthesis

Journal of Bacteriology ◽

10.1128/jb.00798-09 ◽

2009 ◽

Vol 191 (22) ◽

pp. 6796-6803 ◽

Cited By ~ 22

Author(s):

Fatemah A. M. Hermes ◽

John E. Cronan

Keyword(s):

Escherichia Coli ◽

Lipoic Acid ◽

Minimal Medium ◽

Octanoic Acid ◽

Acyl Carrier Protein ◽

Acid Synthesis ◽

Carrier Protein ◽

Missense Mutations ◽

Mutant Strains ◽

Mutant Genes

ABSTRACT The LipB octanoyltransferase catalyzes the first step of lipoic acid synthesis in Escherichia coli, transfer of the octanoyl moiety from octanoyl-acyl carrier protein to the lipoyl domains of the E2 subunits of the 2-oxoacid dehydrogenases of aerobic metabolism. Strains containing null mutations in lipB are auxotrophic for either lipoic acid or octanoic acid. We report the isolation of two spontaneously arising mutant strains that allow growth of lipB strains on glucose minimal medium; we determined that suppression was caused by single missense mutations within the coding sequence of the gene (lplA) that encodes lipoate-protein ligase. The LplA proteins encoded by the mutant genes have reduced Km values for free octanoic acid and thus are able to scavenge cytosolic octanoic acid for octanoylation of lipoyl domains.

Download Full-text

α-proteobacteria synthesize biotin precursor pimeloyl-ACP using BioZ 3-ketoacyl-ACP synthase and lysine catabolism

Nature Communications ◽

10.1038/s41467-020-19251-5 ◽

2020 ◽

Vol 11 (1) ◽

Author(s):

Yuanyuan Hu ◽

John E. Cronan

Keyword(s):

Escherichia Coli ◽

Bacillus Subtilis ◽

Active Site ◽

Acyl Carrier Protein ◽

Acid Synthesis ◽

Side Chain ◽

Carrier Protein ◽

Pimelic Acid ◽

Lysine Degradation ◽

Lysine Catabolism

Abstract Pimelic acid, a seven carbon α,ω-dicarboxylic acid (heptanedioic acid), is known to provide seven of the ten biotin carbon atoms including all those of the valeryl side chain. Distinct pimelate synthesis pathways were recently elucidated in Escherichia coli and Bacillus subtilis where fatty acid synthesis plus dedicated biotin enzymes produce the pimelate moiety. In contrast, the α-proteobacteria which include important plant and mammalian pathogens plus plant symbionts, lack all of the known pimelate synthesis genes and instead encode bioZ genes. Here we report a pathway in which BioZ proteins catalyze a 3-ketoacyl-acyl carrier protein (ACP) synthase III-like reaction to produce pimeloyl-ACP with five of the seven pimelate carbon atoms being derived from glutaryl-CoA, an intermediate in lysine degradation. Agrobacterium tumefaciens strains either deleted for bioZ or which encode a BioZ active site mutant are biotin auxotrophs, as are strains defective in CaiB which catalyzes glutaryl-CoA synthesis from glutarate and succinyl-CoA.

Download Full-text