Doctor of Philosophy, University of California San Francisco (2015)
Bachelor of Science, University of Oregon (2008)
Kerwyn Huang, Postdoctoral Faculty Sponsor
Cutting the Gordian Knot of the Microbiota
2018; 70 (5): 765–67
The gut microbiota plays a central role in human health. Studies by Tramontano et al. (2018) and Maier et al. (2018) improve our understanding of the metabolism and pharmaceutical impact of human gut bacteria through high-throughput screening of growth in the presence of different nutrients and drugs, respectively.
View details for PubMedID 29883604
A genome-wide screen in Escherichia coli reveals that ubiquinone is a key antioxidant for metabolism of long-chain fatty acids
JOURNAL OF BIOLOGICAL CHEMISTRY
2017; 292 (49): 20086–99
Long-chain fatty acids (LCFAs) are used as a rich source of metabolic energy by several bacteria including important pathogens. Because LCFAs also induce oxidative stress, which may be detrimental to bacterial growth, it is imperative to understand the strategies employed by bacteria to counteract such stresses. Here, we performed a genetic screen in Escherichia coli on the LCFA, oleate, and compared our results with published genome-wide screens of multiple non-fermentable carbon sources. This large-scale analysis revealed that among components of the aerobic electron transport chain (ETC), only genes involved in the biosynthesis of ubiquinone, an electron carrier in the ETC, are highly required for growth in LCFAs when compared with other carbon sources. Using genetic and biochemical approaches, we show that this increased requirement of ubiquinone is to mitigate elevated levels of reactive oxygen species generated by LCFA degradation. Intriguingly, we find that unlike other ETC components whose requirement for growth is inversely correlated with the energy yield of non-fermentable carbon sources, the requirement of ubiquinone correlates with oxidative stress. Our results therefore suggest that a mechanism in addition to the known electron carrier function of ubiquinone is required to explain its antioxidant role in LCFA metabolism. Importantly, among the various oxidative stress combat players in E. coli, ubiquinone acts as the cell's first line of defense against LCFA-induced oxidative stress. Taken together, our results emphasize that ubiquinone is a key antioxidant during LCFA metabolism and therefore provides a rationale for investigating its role in LCFA-utilizing pathogenic bacteria.
View details for PubMedID 29042439
View details for PubMedCentralID PMC5723998
A Comprehensive, CRISPR-based Functional Analysis of Essential Genes in Bacteria
2016; 165 (6): 1493-1506
Essential gene functions underpin the core reactions required for cell viability, but their contributions and relationships are poorly studied in vivo. Using CRISPR interference, we created knockdowns of every essential gene in Bacillus subtilis and probed their phenotypes. Our high-confidence essential gene network, established using chemical genomics, showed extensive interconnections among distantly related processes and identified modes of action for uncharacterized antibiotics. Importantly, mild knockdown of essential gene functions significantly reduced stationary-phase survival without affecting maximal growth rate, suggesting that essential protein levels are set to maximize outgrowth from stationary phase. Finally, high-throughput microscopy indicated that cell morphology is relatively insensitive to mild knockdown but profoundly affected by depletion of gene function, revealing intimate connections between cell growth and shape. Our results provide a framework for systematic investigation of essential gene functions in vivo broadly applicable to diverse microorganisms and amenable to comparative analysis.
View details for DOI 10.1016/j.cell.2016.05.003
View details for Web of Science ID 000377045400021
View details for PubMedID 27238023
View details for PubMedCentralID PMC4894308