scholarly journals Identification of parallel and divergent optimization solutions for homologous metabolic enzymes

2018 ◽  
Author(s):  
Robert F. Standaert ◽  
Richard J. Giannone ◽  
Joshua K. Michener
Keyword(s):  
Experimental Evolution ◽  
Single Copy ◽  
Pathway Engineering ◽  
Enzyme Expression ◽  
Heterologous Host ◽  
Pathway Activity ◽  
Potential Factors ◽  
Enzyme Functions ◽  
Pathway Assembly ◽  
Pathway Flux

AbstractMetabolic pathway assembly typically involves the expression of enzymes from multiple organisms in a single heterologous host. Ensuring that each enzyme functions effectively can be challenging, since many potential factors can disrupt proper pathway flux. These challenges are amplified when the enzymes are expressed at single copy from the chromosome. We have explored these issues using 4-hydroxybenzoate monooxygenase homologs heterologously expressed in Escherichia coli. Initial chromosomal enzyme expression was insufficient to support consistent growth with 4-hydroxybenzoate. Experimental evolution identified mutations that improved pathway activity. One set of mutations was common between homologs, while a second class of mutations was homolog-specific. Ultimately, we were able to identify a set of mutations that provided sufficient activity for growth with 4-hydroxybenzoate while maintaining or improving growth with protocatechuate. These findings demonstrate the potential for flexible, scalable chromosomal pathway engineering, as well as the value of directed evolution strategies to rapidly identify and overcome diverse factors limiting enzyme activity.

Staurosporine Derivatives Generated by Pathway Engineering in a Heterologous Host and Their Cytotoxic Selectivity

2018 ◽  
Vol 81 (8) ◽  
pp. 1745-1751 ◽  
Author(s):  
Fei Xiao ◽  
Huayue Li ◽  
Mingyuan Xu ◽  
Tong Li ◽  
Ju Wang ◽  
...  
Keyword(s):  
Pathway Engineering ◽  
Heterologous Host

scholarly journals Understanding Thioamitide Biosynthesis Using Pathway Engineering and Untargeted Metabolomics

2020 ◽  
Author(s):  
Tom H. Eyles ◽  
Natalia M. Vior ◽  
Rodney Lacret ◽  
Andrew W. Truman
Keyword(s):  
Biosynthetic Pathway ◽  
Gene Clusters ◽  
Untargeted Metabolomics ◽  
Pathway Engineering ◽  
Biosynthetic Gene ◽  
Biosynthetic Gene Clusters ◽  
Heterologous Host ◽  
Detailed Understanding ◽  
Precursor Peptide ◽  
Modified Peptides

ABSTRACTThiostreptamide S4 is a thioamitide, a family of promising antitumour ribosomally synthesised and post-translationally modified peptides (RiPPs). The thioamitides are one of the most structurally complex RiPP families, yet very few thioamitide biosynthetic steps have been elucidated, even though the gene clusters of multiple thioamitides have been identified. We hypothesised that engineering the thiostreptamide S4 gene cluster in a heterologous host could provide insights into its biosynthesis when coupled with untargeted metabolomics and targeted mutations of the precursor peptide. Modified gene clusters were constructed, and in-depth metabolomics enabled a detailed understanding of the biosynthetic pathway, including the identification of an effector-like protein critical for amino acid dehydration. We use this biosynthetic understanding to bioinformatically identify new widespread families of RiPP biosynthetic gene clusters, paving the way for future RiPP discovery and engineering.

442: Stromal Hedgehog Pathway Activity Accelerates Prostate Tumor Growth

2006 ◽  
Vol 175 (4S) ◽  
pp. 143-143
Author(s):  
Aubie Shaw ◽  
Jerry Gipp ◽  
Wade Bushman
Keyword(s):  
Tumor Growth ◽  
Prostate Tumor ◽  
Hedgehog Pathway ◽  
Pathway Activity

Identification of a single-copy gene encoding a Type I chlorophyll a/b-binding polypeptide of photosystem I in Arabidopsis thaliana

1992 ◽  
Vol 84 (4) ◽  
pp. 561-567 ◽  
Author(s):  
Poul E. Jensen ◽  
Michael Kristensen ◽  
Tine Hoff ◽  
Jan Lehmbeck ◽  
Bjarne M. Stummann ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Chlorophyll A ◽  
Photosystem I ◽  
Single Copy ◽  
Type I ◽  
Single Copy Gene ◽  
Gene Encoding ◽  
Copy Gene

Implicit and explicit corrective feedback and feedback exposure conditions

2020 ◽  
Vol 4 (1) ◽  
pp. 3-48
Author(s):  
Takehiro Iizuka ◽  
Kimi Nakatsukasa
Keyword(s):  
Explicit Knowledge ◽  
Corrective Feedback ◽  
Significant Difference ◽  
Oral Corrective Feedback ◽  
Post Test ◽  
Picture Description ◽  
Potential Factors ◽  
Implicit And Explicit ◽  
Instructional Settings ◽  
The Impact

This exploratory study examined the impact of implicit and explicit oral corrective feedback (CF) on the development of implicit and explicit knowledge of Japanese locative particles (activity de, movement ni and location ni) for those who directly received CF and those who observed CF in the classroom. Thirty-six college students in a beginning Japanese language course received either recast (implicit), metalinguistic (explicit) or no feedback during an information-gap picture description activity, and completed a timed picture description test (implicit knowledge) and an untimed grammaticality judgement test (explicit knowledge) in a pre-test, immediate post-test and delayed post-test. The results showed that overall there was no significant difference between CF types, and that CF benefited direct and indirect recipients similarly. Potential factors that might influence the effectiveness of CF, such as instructional settings, complexity of target structures and pedagogy styles, are discussed.

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