Functional Genomic Study of Exogenous n-Butanol Stress in Escherichia coli

• Published in: Applied and Environmental Microbiology Vol. 76; no. 6; pp. 1935 - 1945
• Main Authors: Rutherford, Becky J, Dahl, Robert H, Price, Richard E, Szmidt, Heather L, Benke, Peter I, Mukhopadhyay, Aindrila, Keasling, Jay D
• Format: Journal Article
• Language: English
• Published: United States American Society for Microbiology 01-03-2010; American Society for Microbiology (ASM)
• Subjects: 1-Butanol - toxicity; Biofuels; biosynthesis; Biotechnology; butanol; E coli; engineering; Escherichia coli; Escherichia coli - drug effects; Escherichia coli - physiology; Ethanol; fluorescent dyes; Gene Expression Profiling; Gene Expression Regulation, Bacterial; Genes; genetic engineering; Genomics; heat stress; hosts; messenger RNA; Metabolome; microarray technology; microorganisms; Mutation; operon; oxidative stress; Oxygen; proteins; Proteome - analysis; Proteomics; reactive oxygen species; Reactive Oxygen Species - metabolism; stress response; Stress, Physiological; Toxicity
• ISSN: 0099-2240; 1098-5336; 1098-6596
• DOI: 10.1128/AEM.02323-09

n-Butanol has been proposed as an alternative biofuel to ethanol, and several industrially used microbes, including Escherichia coli, have been engineered to produce it. Unfortunately, n-butanol is more toxic than ethanol to these organisms. To understand the basis for its toxicity, cell-wide studies were conducted at the transcript, protein, and metabolite levels to obtain a global view of the n-butanol stress response. Analysis of the data indicates that n-butanol stress has components common to other stress responses, including perturbation of respiratory functions (nuo and cyo operons), oxidative stress (sodA, sodC, and yqhD), heat shock and cell envelope stress (rpoE, clpB, htpG, cpxR, and cpxP), and metabolite transport and biosynthesis (malE and opp operon). Assays using fluorescent dyes indicated a large increase in reactive oxygen species during n-butanol stress, confirming observations from the microarray and proteomics measurements. Mutant strains with mutations in several genes whose products changed most dramatically during n-butanol stress were examined for increased sensitivity to n-butanol. Results from these analyses allowed identification of key genes that were recruited to alleviate oxidative stress, protein misfolding, and other causes of growth defects. Cellular engineering based on these cues may assist in developing a high-titer, n-butanol-producing host.