Generalized Transduction

Thierauf, Anne; Perez, Gerardo Legrama; Maloy, and Stanley

doi:10.1007/978-1-60327-164-6_23

Cited by 67 publications

(48 citation statements)

References 95 publications

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“…Both genes were integrated into the mal gene locus (under the control of a P tac -promoter) following described methods [[45],[51]–[53]]. On MacConkey agar pH indicator plates with 1% glycerol, it became visible that each of the glpK alleles was able to reconstitute a glycerol-positive phenotype (acid formation from glycerol) of LJ110 ∆ glpK .…”

Section: Resultsmentioning

confidence: 99%

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Improvement of L-phenylalanine production from glycerol by recombinant Escherichia coli strains: The role of extra copies of glpK, glpX, and tktA genes

2014

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BackgroundFor the production of L-phenylalanine (L-Phe), two molecules of phosphoenolpyruvate (PEP) and one molecule erythrose-4-phosphate (E4P) are necessary. PEP stems from glycolysis whereas E4P is formed in the pentose phosphate pathway (PPP). Glucose, commonly used for L-Phe production with recombinant E. coli, is taken up via the PEP-dependent phosphotransferase system which delivers glucose-6-phosphate (G6P). G6P enters either glycolysis or the PPP. In contrast, glycerol is phosphorylated by an ATP-dependent glycerol kinase (GlpK) thus saving one PEP. However, two gluconeogenic reactions (fructose-1,6-bisphosphate aldolase, fructose-1,6-bisphosphatase, FBPase) are necessary for growth and provision of E4P. Glycerol has become an important carbon source for biotechnology and reports on production of L-Phe from glycerol are available. However, the influence of FBPase and transketolase reactions on L-Phe production has not been reported.ResultsL-Phe productivity of parent strain FUS4/pF81 (plasmid-encoded genes for aroF, aroB, aroL, pheA) was compared on glucose and glycerol as C sources. On glucose, a maximal carbon recovery of 0.19 mM CPhe/CGlucose and a maximal space-time-yield (STY) of 0.13 g l−1 h−1 was found. With glycerol, the maximal carbon recovery was nearly the same (0.18 mM CPhe/CGlycerol), but the maximal STY was higher (0.21 g l−1 h−1). We raised the chromosomal gene copy number of the genes glpK (encoding glycerol kinase), tktA (encoding transketolase), and glpX (encoding fructose-1,6-bisphosphatase) individually. Overexpression of glpK (or its feedback-resistant variant, glpKG232D) had little effect on growth rate; L-Phe production was about 30% lower than in FUS4/pF81. Whereas the overexpression of either glpX or tktA had minor effects on productivity (0.20 mM CPhe/CGlycerol; 0.25 g l−1 h−1 and 0.21 mM CPhe/CGlycerol; 0.23 g l−1 h−1, respectively), the combination of extra genes of glpX and tktA together led to an increase in maximal STY of about 80% (0.37 g l−1 h−1) and a carbon recovery of 0.26 mM CPhe/CGlycerol.ConclusionsEnhancing the gene copy numbers for glpX and tktA increased L-Phe productivity from glycerol without affecting growth rate. Engineering of glycerol metabolism towards L-Phe production in E. coli has to balance the pathways of gluconeogenesis, glycolysis, and PPP to improve the supply of the precursors, PEP and E4P.

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Section: Resultsmentioning

confidence: 99%

“…Cm-resistant colonies were tested for correct location by PCR with appropriate primers (Table 4). Chromosomal modifications were first conducted in derivatives of strain BW25113 and then transferred by P1-mediated transductions into the FUS4 background [[52],[53]]. Strain constructs are listed and described in Table 1.…”

Section: Methodsmentioning

confidence: 99%

Improvement of L-phenylalanine production from glycerol by recombinant Escherichia coli strains: The role of extra copies of glpK, glpX, and tktA genes

2014

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“…There are three well-studied types of HGT in microbes (see sidebar, Types of Horizontal Gene Transfer Used by Bacteria): ( a ) transformation, the natural ability to take up exogenous DNA from the environment (reviewed in 84); ( b ) transduction, the transfer of DNA from one cell to another by bacteriophage (140 and references therein); and ( c ) conjugation, the contact-dependent, unidirectional transfer of DNA from a donor to a recipient via a conjugation (or mating) apparatus expressed in the donor [first described by Lederberg & Tatum (87)]. Transduction and conjugation are both mediated by mobile genetic elements, which can mediate their own transfer from one cell to another.…”

Section: Introductionmentioning

confidence: 99%

Integrative and Conjugative Elements (ICEs): What They Do and How They Work

Johnson

Grossman²

2015

Annu. Rev. Genet.

487

503

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Horizontal gene transfer plays a major role in microbial evolution, allowing microbes to acquire new genes and phenotypes. Integrative and conjugative elements (ICEs, a.k.a. conjugative transposons) are modular mobile genetic elements integrated into a host genome and are passively propagated during chromosomal replication and cell division. Induction of ICE gene expression leads to excision, production of the conserved conjugation machinery (a type IV secretion system), and the potential to transfer DNA to appropriate recipients. ICEs typically contain cargo genes that are not usually related to the ICE life cycle and that confer phenotypes to host cells. We summarize the life cycle and discovery of ICEs, some of the regulatory mechanisms, and how the types of cargo have influenced our view of ICEs. We discuss how ICEs can acquire new cargo genes and describe challenges to the field and various perspectives on ICE biology.

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“…The oligonucleotides used for generating deletion mutants are detailed in Table 2 (15). Mutations were made in the S. Typhimurium 14028 strain background (American Type Culture Collection, Manassas, VA), verified by PCR, and transduced into SL1344 using standard P22 phage transduction (63). Transductants were verified by growth on LB agar containing the appropriate antibiotic and by PCR.…”

Section: Methodsmentioning

confidence: 99%

A Protein Important for Antimicrobial Peptide Resistance, YdeI/OmdA, Is in the Periplasm and Interacts with OmpD/NmpC

et al. 2009

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Antimicrobial peptides (AMPs) kill or prevent the growth of microbes. AMPs are made by virtually all single and multicellular organisms and are encountered by bacteria in diverse environments, including within a host. Bacteria use sensor-kinase systems to respond to AMPs or damage caused by AMPs. Salmonella enterica deploys at least three different sensor-kinase systems to modify gene expression in the presence of AMPs: PhoP-PhoQ, PmrA-PmrB, and RcsB-RcsC-RcsD. The ydeI gene is regulated by the RcsB-RcsC-RcsD pathway and encodes a 14-kDa predicted oligosaccharide/oligonucleotide binding-fold (OB-fold) protein important for polymyxin B resistance in broth and also for virulence in mice. We report here that ydeI is additionally regulated by the PhoP-PhoQ and PmrA-PmrB sensor-kinase systems, which confer resistance to cationic AMPs by modifying lipopolysaccharide (LPS). ydeI, however, is not important for known LPS modifications. Two independent biochemical methods found that YdeI copurifies with OmpD/NmpC, a member of the trimeric ␤-barrel outer membrane general porin family. Genetic analysis indicates that ompD contributes to polymyxin B resistance, and both ydeI and ompD are important for resistance to cathelicidin antimicrobial peptide, a mouse AMP produced by multiple cell types and expressed in the gut. YdeI localizes to the periplasm, where it could interact with OmpD. A second predicted periplasmic OB-fold protein, YgiW, and OmpF, another general porin, also contribute to polymyxin B resistance. Collectively, the data suggest that periplasmic OB-fold proteins can interact with porins to increase bacterial resistance to AMPs.

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Generalized Transduction

Cited by 67 publications

References 95 publications

Improvement of L-phenylalanine production from glycerol by recombinant Escherichia coli strains: The role of extra copies of glpK, glpX, and tktA genes

Improvement of L-phenylalanine production from glycerol by recombinant Escherichia coli strains: The role of extra copies of glpK, glpX, and tktA genes

Integrative and Conjugative Elements (ICEs): What They Do and How They Work

A Protein Important for Antimicrobial Peptide Resistance, YdeI/OmdA, Is in the Periplasm and Interacts with OmpD/NmpC

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