Mechanism, biological relevance, and structural requirements for thiolate additions to bicyclomycin and analogs. A unique latent Michael acceptor system

Williams, Robert M.; Tomizawa, Kohtaro; Armstrong, Robert W.; Dung, Jen Sen

doi:10.1021/ja00247a032

Cited by 18 publications

(24 citation statements)

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“…Early reports on the 1 inhibition pathway suggested that the antibiotic irreversibly modified its receptor(s) [27][28][29][30][31][32][33]. Indeed, our chemical studies showed that 1 covalently reacted with thiols and amines under moderate conditions [39][40][41][42][43], so we asked if a comparable process occurred with rho.…”

Section: Bicyclomycin Inhibits Rho By a Reversible Pathwaymentioning

confidence: 93%

“…Bicyclomycin was reported by several researchers to affect bacterial outer-membrane synthesis [27][28][29][30][31][32][33]. First, administering 1 to E. coli modified cell wall synthesis but had little effect on DNA, lipid, or cell-free protein synthesis [28].…”

Section: Early Proposals Of Bicyclomycin Function: Insights Into Bicymentioning

confidence: 99%

“…Initial proposals for the mode of action of 1 suggested that its antibacterial activity was associated with covalent modification of nucleophilic species present within the peptidoglycan assembly of the bacterial cell wall [27][28][29][30][31][32][33].…”

Section: Introductionmentioning

confidence: 99%

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The Molecular Basis for the Mode of Action of Bicyclomycin

Kohn

Widger

2005

CDTID

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Bicyclomycin (1) is a clinically useful antibiotic exhibiting activity against a broad spectrum of Gram-negative bacteria and against the Gram-positive bacterium, Micrococcus luteus. Bicyclomycin has been used to treat diarrhea in humans and bacterial diarrhea in calves and pigs and is marketed by Fujisawa (Osaka, Japan) under the trade name Bicozamycin. The structure of 1 is unique among antibiotics, and our studies document that its mechanism of action is novel. Early mechanistic proposals suggested that 1 reacted with nucleophiles (e.g., a protein sulfhydryl group) necessary for the remodeling the peptidoglycan assembly within the bacterial cell wall. We, however, showed that 1 targeted the rho transcription termination factor in Escherichia coli. The rho protein is integral to the expression of many gene products in E. coli and other Gram-negative bacteria, and without rho the cell losses viability. Rho is a member of the RecA-type ATPase class of enzymes that use nucleotide contacts to couple oligonucleotide translocation to ATP hydrolysis. Bicyclomycin is the only known selective inhibitor of rho. In this article, we integrate the evidence obtained from bicyclomycin structure-activity studies, site-directed mutagenesis investigations, bicyclomycin affinity labels, and biochemical and biophysical measurements with recent X-ray crystallographic images of the bicyclomycin-rho complex to define the rho antibiotic binding site and to document the pathway for rho inhibition by 1. Together, the structural and functional studies demonstrate how 1, a modest rho inhibitor, can disrupt the rho molecular machinery thereby leading to a catastrophic effect caused by the untimely overproduction of proteins not normally expressed constitutively, thus leading to a toxic effect on the cells.

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Section: Bicyclomycin Inhibits Rho By a Reversible Pathwaymentioning

confidence: 93%

Section: Early Proposals Of Bicyclomycin Function: Insights Into Bicymentioning

confidence: 99%

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The Molecular Basis for the Mode of Action of Bicyclomycin

Kohn

Widger

2005

CDTID

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“…5 Kohn and co-workers subsequently discovered that, depending on the pH of the medium, different thiol-addition products were produced including an interesting Claisen rearrangement product 13 . 6 Based on the interesting and novel chemical (and later, biochemical) reactivity of bicyclomycin that was emerging, we wondered if the bridging ether oxygen atom was obligatory for antimicrobial activity or was a spectator atom (Figure 1). …”

Section: Introductionmentioning

confidence: 99%

Natural Products Synthesis: Enabling Tools To Penetrate Nature’s Secrets of Biogenesis and Biomechanism

Williams

2011

J. Org. Chem.

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Selected examples from our laboratory of how synthetic technology platforms developed for the total synthesis of several disparate families of natural products was harnessed to penetrate biomechanistic and/or biosynthetic queries is discussed. Unexpected discoveries of biomechanistic reactivity and/or penetrating the biogenesis of naturally occurring substances were made possible through access to substances available only through chemical synthesis. Hypothesis-driven total synthesis programs are emerging as very useful conceptual templates for penetrating and exploiting the inherent reactivity of biologically active natural substances. In many instances, new enabling synthetic technologies were required to be developed. The examples demonstrate the often un-tapped richness of complex molecule synthesis to provide powerful tools to understand, manipulate and exploit Nature’s vast and creative palette of secondary metabolites.

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“…The acidcatalysed addition of the amide nitrogen to the pyruvic keto group should give an intermediate carbinolamide which gives rise in turn to the final products. Bicyclomycin [20] and several of its synthetic analogues can be considered outstanding examples of exceedingly stable cyclic carbinolamides where a carboxamide group adds to the keto group of the cu-keto acid moiety of the molecule.…”

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confidence: 99%

Functional residues at the active site of horse liver phosphopantothenoylcysteine decarboxylase

et al. 1988

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Horse liver phosphopantothenoylcysteine decarboxylase (EC 4.1.1.36) is rapidly inactivated by N-acetoacetylation with diketene following a pseudo-first-order kinetics: the presence of substrate quantitatively protects against this inactivation. Histidine photo-oxidation with methylene blue or rose bengal brings about the total loss of activity. These results indicate the presence of functional lysyl and histidyl groups at the active site of the enzyme. The substrate sulphydryl group is essential for enzyme activity. Enzymatic decarboxylation is proposed to result from a combined action of the keto group of the enzyme-bound pyruvate protonated by an essential histidine and a protonated amino group of a lysine.

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Mechanism, biological relevance, and structural requirements for thiolate additions to bicyclomycin and analogs. A unique latent Michael acceptor system

Cited by 18 publications

References 0 publications

The Molecular Basis for the Mode of Action of Bicyclomycin

The Molecular Basis for the Mode of Action of Bicyclomycin

Natural Products Synthesis: Enabling Tools To Penetrate Nature’s Secrets of Biogenesis and Biomechanism

Functional residues at the active site of horse liver phosphopantothenoylcysteine decarboxylase

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