Mutations in Escherichia coli aceE and ribB Genes Allow Survival of Strains Defective in the First Step of the Isoprenoid Biosynthesis Pathway

Jordi Perez-Gil,Manuel Rodriguez-Concepcion,Eva Maria Uros,Minobu Nishimoto,Jay D Keasling,Albert Boronat,L Maria Lois,Edward E K Baidoo,James Kirby,Susanna Sauret-Güeto

doi:10.1371/journal.pone.0043775

Jordi Perez-Gil, Manuel Rodriguez-Concepcion + Show 8 more

Open Access

https://doi.org/10.1371/journal.pone.0043775

Copy DOI

Abstract

A functional 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway is required for isoprenoid biosynthesis and hence survival in Escherichia coli and most other bacteria. In the first two steps of the pathway, MEP is produced from the central metabolic intermediates pyruvate and glyceraldehyde 3-phosphate via 1-deoxy-D-xylulose 5-phosphate (DXP) by the activity of the enzymes DXP synthase (DXS) and DXP reductoisomerase (DXR). Because the MEP pathway is absent from humans, it was proposed as a promising new target to develop new antibiotics. However, the lethal phenotype caused by the deletion of DXS or DXR was found to be suppressed with a relatively high efficiency by unidentified mutations. Here we report that several mutations in the unrelated genes aceE and ribB rescue growth of DXS-defective mutants because the encoded enzymes allowed the production of sufficient DXP in vivo. Together, this work unveils the diversity of mechanisms that can evolve in bacteria to circumvent a blockage of the first step of the MEP pathway.

Highlights

Isoprenoids are a ubiquitous and highly diverse family of compounds produced from the five-carbon precursor isopentenyl diphosphate (IPP) and its double-bond isomer dimethylallyl diphosphate (DMAPP) in all living organisms [1,2,3]
To discriminate between the remaining possibilities, we investigated whether the presence of mutant versions of PDH or dihydroxy-2-butanone 4-phosphate synthase (DHBPS) resulted in the production of D-xylulose 5-phosphate (DXP) in cells lacking both DXP synthase (DXS) and DXP reductoisomerase (DXR) activities
Most bacteria only use the methyl-D-erythritol 4phosphate (MEP) pathway for IPP and DMAPP biosynthesis, but there are exceptions to this trend. Some bacteria synthesize their isoprenoid precursors using the mevalonic acid (MVA) pathway instead of the MEP pathway, whereas there are parasitic bacteria that lack both pathways and organisms that possess the two full pathways [3,31,32,33,34]

Summary

Introduction

Isoprenoids ( called terpenoids) are a ubiquitous and highly diverse family of compounds produced from the five-carbon precursor isopentenyl diphosphate (IPP) and its double-bond isomer dimethylallyl diphosphate (DMAPP) in all living organisms [1,2,3]. These precursors are synthesized from acetyl-CoA by the mevalonic acid (MVA) pathway in archaea (archaebacteria), fungi, and animals. Because the MEP pathway is essential in such pathogens but is not present in animals, it has been proposed as a promising target for the design of new antibacterial and antimalarial agents that would be potentially innocuous for humans [6,7,8]. The initial reaction of the pathway (Fig. 1) is catalyzed by 1-deoxy-D-xylulose 5-phosphate (DXP)

Objectives

Methods

Results

Conclusion