title: The aldehyde dehydrogenase, AldA, is essential for L-1,2-propanediol utilization in laboratory-evolved Escherichia coli.
abstract: Most Escherichia coli strains are naturally unable to grow on 1,2-propanediol (PDO) as a sole carbon source. Recently, however, a K-12 descendent E. coli strain was evolved to grow on 1,2-PDO, and it was hypothesized that this evolved ability was dependent on the aldehyde dehydrogenase, AldA, which is highly conserved among members of the family Enterobacteriacea. To test this hypothesis, we first performed computational model simulation, which confirmed the essentiality of the aldA gene for 1,2-PDO utilization by the evolved PDO-degrading E. coli. Next, we deleted the aldA gene from the evolved strain, and this deletion was sufficient to abolish the evolved phenotype. On re-introducing the gene on a plasmid, the evolved phenotype was restored. These findings provide experimental evidence for the computationally predicted role of AldA in 1,2-PDO utilization, and represent a good example of E. coli robustness, demonstrated by the bacterial deployment of a generalist enzyme (here AldA) in multiple pathways to survive carbon starvation and to grow on a non-native substrate when no native carbon source is available.
authors.affiliation: Department of Microbiology and Immunology, Faculty of Pharmacy, Cairo University, Cairo, Egypt; Department of Bioengineering, University of California San Diego, La Jolla, CA, USA. Electronic address: ramy.aziz@gmail.com.
authors.forename: Ramy K
authors.initials: RK
authors.lastname: Aziz
authors.affiliation: Department of Bioengineering, University of California San Diego, La Jolla, CA, USA.
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Monk
authors.affiliation: Department of Bioengineering, University of California San Diego, La Jolla, CA, USA.
authors.forename: Kathleen A
authors.initials: KA
authors.lastname: Andrews
authors.affiliation: Department of Bioengineering, University of California San Diego, La Jolla, CA, USA.
authors.forename: Jenny
authors.initials: J
authors.lastname: Nhan
authors.affiliation: Department of Bioengineering, University of California San Diego, La Jolla, CA, USA.
authors.forename: Valerie L
authors.initials: VL
authors.lastname: Khaw
authors.affiliation: Department of Bioengineering, University of California San Diego, La Jolla, CA, USA.
authors.forename: Hesper
authors.initials: H
authors.lastname: Wong
authors.affiliation: Department of Bioengineering, University of California San Diego, La Jolla, CA, USA; Department of Pediatrics, University of California San Diego, La Jolla, CA, USA.
authors.forename: Bernhard O
authors.initials: BO
authors.lastname: Palsson
authors.affiliation: Department of Bioengineering, University of California San Diego, La Jolla, CA, USA; The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Hørsholm, Denmark. Electronic address: pcharusanti@ucsd.edu.
authors.forename: Pep
authors.initials: P
authors.lastname: Charusanti
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology; D000444:Aldehyde Dehydrogenase / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D018076:DNA, Complementary / Q000235:genetics; D019020:Directed Molecular Evolution; D048168:Escherichia coli K12 / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D016680:Genome, Bacterial; D053858:Metabolic Networks and Pathways; D010641:Phenotype; D010957:Plasmids / Q000235:genetics; D019946:Propylene Glycol / Q000378:metabolism*; D012329:RNA, Bacterial / Q000302:isolation & purification; D060888:Real-Time Polymerase Chain Reaction; D017384:Sequence Deletion
chemical_list: D018076:DNA, Complementary; D029968:Escherichia coli Proteins; D012329:RNA, Bacterial; D019946:Propylene Glycol; D000444:Aldehyde Dehydrogenase
keywords: Adaptive laboratory evolution; Genome-scale models; Microbial metabolilsm; Pathway gap filling; Systems biology