Engineering microbial biofuel tolerance and export using efflux pumps.
Summary of "Engineering microbial biofuel tolerance and export using efflux pumps."
Many compounds being considered as candidates for advanced biofuels are toxic to microorganisms. This introduces an undesirable trade-off when engineering metabolic pathways for biofuel production because the engineered microbes must balance production against survival. Cellular export systems, such as efflux pumps, provide a direct mechanism for reducing biofuel toxicity. To identify novel biofuel pumps, we used bioinformatics to generate a list of all efflux pumps from sequenced bacterial genomes and prioritized a subset of targets for cloning. The resulting library of 43 pumps was heterologously expressed in Escherichia coli, where we tested it against seven representative biofuels. By using a competitive growth assay, we efficiently distinguished pumps that improved survival. For two of the fuels (n-butanol and isopentanol), none of the pumps improved tolerance. For all other fuels, we identified pumps that restored growth in the presence of biofuel. We then tested a beneficial pump directly in a production strain and demonstrated that it improved biofuel yields. Our findings introduce new tools for engineering production strains and utilize the increasingly large database of sequenced genomes.
Affiliation
1] Joint BioEnergy Institute, Emeryville, CA, USA [2] University of Vermont, Burlington, VT, USA [3] Lawrence Berkeley Laboratory, Berkeley, CA, USA.
Journal Details
This article was published in the following journal.
Name: Molecular systems biology
ISSN: 1744-4292
Pages: 487
Links
- PubMed Source: http://www.ncbi.nlm.nih.gov/pubmed/21556065
- DOI: http://dx.doi.org/10.1038/msb.2011.21
Medical and Biotech [MESH] Definitions
Arsenite Transporting Atpases
Efflux pumps that use the energy of ATP hydrolysis to pump arsenite across a membrane. They are primarily found in prokaryotic organisms, where they play a role in protection against excess intracellular levels of arsenite ions.
Nuclear Export Signals
Specific amino acid sequences present in the primary amino acid sequence of proteins which mediate their export from the CELL NUCLEUS. They are rich in hydrophobic residues, such as LEUCINE and ISOLEUCINE.
Rhodamine 123
A fluorescent probe with low toxicity which is a potent substrate for P-glycoprotein and the bacterial multidrug efflux transporter. It is used to assess mitochondrial bioenergetics in living cells and to measure the efflux activity of P-glycoprotein in both normal and malignant cells. (Leukemia 1997;11(7):1124-30)
P-glycoproteins
A subfamily of transmembrane proteins from the superfamily of ATP-BINDING CASSETTE TRANSPORTERS that are closely related in sequence to P-GLYCOPROTEIN. When overexpressed, they function as ATP-dependent efflux pumps able to extrude lipophilic drugs, especially ANTINEOPLASTIC AGENTS, from cells causing multidrug resistance (DRUG RESISTANCE, MULTIPLE). Although P-Glycoproteins share functional similarities to MULTIDRUG RESISTANCE-ASSOCIATED PROTEINS they are two distinct subclasses of ATP-BINDING CASSETTE TRANSPORTERS, and have little sequence homology.
Sanitary Engineering
A branch of engineering concerned with the design, construction, and maintenance of environmental facilities conducive to public health, such as water supply and waste disposal.
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