Membrane-Related Science

Joseph Webb, Vicki Springthorpe, Luca Rossoni, David-Paul Minde, Swen Langer, Heather Walker, Amias Alstrom-Moore, Tony Larson, Kathryn Lilley, Graham Eastham, Gill Stephens, Gavin H. Thomas, David J. Kelly, Jeffrey Green

Citramalate is an attractive biotechnology target because it is a precursor of methylmethacrylate, which is used to manufacture Perspex and other high-value products. Engineered E. coli strains are able to produce high titers of citramalate, despite having to express a foreign enzyme and tolerate the presence of a nonnative biochemical. A systems analysis of the citramalate fermentation was undertaken to uncover the reasons underpinning its productivity. This showed that E. coli readily adjusts to the redirection of metabolic resources toward recombinant protein and citramalate production and suggests that E. coli is an excellent chassis for manufacturing similar small, polar, foreign molecules. (read more…)

Calum A. Pattrick, Joseph P. Webb, Jeffrey Green, Roy R. Chaudhuri, Mark O. Collins, David J. Kelly

A particular problem for the biotechnological production of many of the valuable chemicals that we are now able to manufacture in bacterial cells is that these products often poison the cells producing them. Solutions to improve product yields or alleviate such toxicity using the techniques of modern molecular biology first require a detailed understanding of the mechanisms of product toxicity. Here we have studied the economically important flavor compound vanillin, an aromatic aldehyde that exerts significant toxic effects on bacterial cells. We used high-resolution protein abundance analysis as a starting point to determine which proteins are upregulated and which are downregulated by growth with vanillin, followed by gene expression and mutant studies to understand the mechanism of the response. In a second approach, we evolved bacterial strains with higher vanillin tolerance. Their genome sequences have yielded novel insights into vanillin tolerance that are complementary to the proteomics data set. (read more…)

Rebecca M. Lennen, Kristian Jensen, Elsayed T. Mohammed, Sailesh Malla, Rosa A. Börner, Ksenia Chekina, Emre Özdemir, Ida Bonde, Anna Koza, Jérôme Maury, Lasse E. Pedersen, Lars Y. Schöning, Nikolaus Sonnenschein, Bernhard O. Palsson, Morten O.A. Sommer, Adam M. Feist, Alex T. Nielsen, Markus J. Herrgård

Tolerance to high product concentrations is a major barrier to achieving economically viable processes for bio-based chemical production. Chemical tolerance mechanisms are often unknown, thus their rational design is not achievable. To reveal unknown tolerance mechanisms we used an automated platform to evolve Escherichia coli to grow in previously toxic concentrations of 11 chemicals that have applications as polymer precursors, chemical intermediates, or biofuels. (read more…)

Yusuke Sasaki, Thomas Eng, Robin A. Herbert, Jessica Trinh, Yan Chen, Alberto Rodriguez, John Gladden, Blake A. Simmons, Christopher J. Petzold and Aindrila Mukhopadhyay

Background: Many microbes used for the rapid discovery and development of metabolic pathways have sensitivities to final products and process reagents. Isopentenol (3-methyl-3-buten-1-ol), a biogasoline candidate, has an established heterologous gene pathway but is toxic to several microbial hosts. Reagents used in the pretreatment of plant biomass, such as ionic liquids, also inhibit growth of many host strains. We explored the use of Corynebacterium glutamicum as an alternative host to address these constraints. (read more…)

Miaomiao Li, Christoph Müller, Klemens Fröhlich, Oliver Gorka, Lin Zhang, Olaf Groß, Oliver Schilling, Oliver Einsle, Claudia Jessen-Trefzer

Nutrient uptake is essential for survival of organisms, and carbohydrates serve as a crucial carbon and energy source for most microorganisms. Given the importance of mycobacteria as human pathogens a detailed knowledge of carbohydrate uptake transporters is highly desirable, but currently available information is severely limited and mainly based on in silico analyses. (read more…)

Wooseok Ko, Rahul Kumar, Sanggil Kim, and Hyun Soo Lee

Engineered organisms with an expanded genetic code have attracted much attention in chemical and synthetic biology research. In this work, engineered bacterial organisms with enhanced unnatural amino acid (UAA) uptake abilities were developed by screening periplasmic binding protein (PBP) mutants for recognition of UAAs. (read more…)

Kenta Tsutsumi, Ryo Yonehara, Etsuko Ishizaka-Ikeda, Naoyuki Miyazaki, Shintaro Maeda, Kenji Iwasaki, Atsushi Nakagawa & Eiki Yamashita

In Pseudomonas aeruginosa, MexAB–OprM plays a central role in multidrug resistance by ejecting various drug compounds, which is one of the causes of serious nosocomial infections. (read more…)

Nuria Gómez-Santos, Timo Glatter, Ralf Koebnik, Magdalena Anna Świątek-Połatyńska & Lotte Søgaard-Andersen

TonB-dependent transporters (TBDTs) are ubiquitous outer membrane β-barrel proteins that import nutrients and bacteriocins across the outer membrane in a proton motive force-dependent manner, by directly connecting to the ExbB/ExbD/TonB system in the inner membrane. (read more…)

Alexander Jussupow, Andrea Di Luca and Ville R. I. Kaila

Cardiolipin modulates the activity of membrane-bound respiratory enzymes that catalyze biological energy transduction. The respiratory complex I functions as the primary redox-driven proton pump in mitochondrial and bacterial respiratory chains, and its activity is strongly enhanced by cardiolipin. (read more…)

Alvin C. K. Teo, Sarah C. Lee, Naomi L. Pollock, Zoe Stroud, Stephen Hall, Alpesh Thakker, Andrew R. Pitt, Timothy R. Dafforn, Corinne M. Spickett & David I. Roper

Biological characterisation of membrane proteins lags behind that of soluble proteins. This reflects issues with the traditional use of detergents for extraction, as the surrounding lipids are generally lost, with adverse structural and functional consequences. (read more…)

Sang Yup Lee, Hyun Uk Kim, Tong Un Chae, Jae Sung Cho, Je Woong Kim, Jae Ho Shin, Dong In Kim, Yoo-Sung Ko, Woo Dae Jang & Yu-Sin Jang

Production of industrial chemicals using renewable biomass feedstock is becoming increasingly important to address limited fossil resources, climate change and other environmental problems.  (read more…)

Benjamin J. Willson, Lindsey Dalzell, Liam N. M. Chapman, Gavin H. Thomas

The evolution of gene fusions that result in covalently linked protein domains is widespread in bacteria, where spatially coupling domain functionalities can have functional advantages in vivo.Fusions to integral membrane proteins are less widely studied but could provide routes to enhance membrane function in synthetic biology. (read more…)

A recent publication from CBMNet member Graham Stafford at the University of Sheffield. The research in this article was supported by a Proof-of-Concept Funding and by a Business Interaction Voucher from CBMNet (follow the links to read the case studies) and was part of a long-standing collaboration with Fujifilm Diosynth Biotechnologies. (read more…)

Yanli Qi Hui Liu Xiulai Chen Liming Liu

The microbial membrane serves as a biological barrier that separates the interior of cells from the external environment, thus playing an important role in tolerance to stress conditions during industrial bioprocessing. (read more…)

A recent publication from CBMNet member Claudio Angione at Teesside University. The research in this article was supported by a CBMNet Business Interaction Voucher (read the case study here) and continues to be supported by an ongoing CBMNet Proof-of-Concept Award. (read more…)

Jae Woong Choi, Eun Jung Jeon, Ki Jun Jeong

Corynebacterium glutamicum has been mainly used for industrial production of amino acids, and in recent years, it has also been successfully engineered to broaden its range of substrate and product profiles. (read more…)

Huan Fang, Dong Li, Jie Kang, Pingtao Jiang, Jibin Sun & Dawei Zhang

The only known source of vitamin B12 (adenosylcobalamin) is from bacteria and archaea. Here, using genetic and metabolic engineering, we generate an Escherichia coli strain that produces vitamin B12 via an engineered de novo aerobic biosynthetic pathway. (read more…)

Thomas Eng, Philipp Demling, Robin A. Herbert, Yan Chen, Veronica Benites, Joel Martin, Anna Lipzen, Edward E. K. Baidoo, Lars M. Blank, Christopher J. Petzold, Aindrila Mukhopadhyay


Microbial production of chemicals from renewable carbon sources enables a sustainable route to many bioproducts. Sugar streams, such as those derived from biomass pretreated with ionic liquids (IL), provide efficiently derived and cost-competitive starting materials. A limitation to this approach is that residual ILs in the pretreated sugar source can be inhibitory to microbial growth and impair expression of the desired biosynthetic pathway.

(read more…)

Angad P. MehtaLubica SupekovaJian-Hua ChenKersi PestonjamaspPaul WebsterYeonjin KoScott C. HendersonGerry McDermottFrantisek Supek, and Peter G. Schultz

Endosymbiotic theory suggests that mitochondria evolved from free-living prokaryotes which entered the host cell and were retained as endosymbionts. Here, we model this earliest stage of the endosymbiotic theory of mitochondrial evolution by engineering endosymbiosis between two genetically tractable model organisms, Escherichia coli and Saccharomyces cerevisiae. (read more…)

Itay Budin, Tristan de Rond, Yan Chen, Leanne Jade G. Chan, Christopher J. Petzold, Jay D. Keasling

Lipid composition determines the physical properties of biological membranes and can vary substantially between and within organisms. We describe a specific role for the viscosity of energy-transducing membranes in cellular respiration. (read more…)