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Kaczmarek JA, Prather KLJ. Effective use of biosensors for high-throughput library screening for metabolite production. J Ind Microbiol Biotechnol 2021; 48:6339276. [PMID: 34347108 PMCID: PMC8788864 DOI: 10.1093/jimb/kuab049] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2021] [Accepted: 07/19/2021] [Indexed: 11/14/2022]
Abstract
The development of fast and affordable microbial production from recombinant pathways is a challenging endeavor, with targeted improvements difficult to predict due to the complex nature of living systems. To address the limitations in biosynthetic pathways, much work has been done to generate large libraries of various genetic parts (promoters, RBSs, enzymes, etc.) to discover library members that bring about significantly improved levels of metabolite production. To evaluate these large libraries, high throughput approaches are necessary, such as those that rely on biosensors. There are various modes of operation to apply biosensors to library screens that are available at different scales of throughput. The effectiveness of each biosensor-based method is dependent on the pathway or strain to which it is applied, and all approaches have strengths and weaknesses to be carefully considered for any high throughput library screen. In this review, we discuss the various approaches used in biosensor screening for improved metabolite production, focusing on transcription factor-based biosensors.
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Affiliation(s)
- Jennifer A Kaczmarek
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge 02142, USA
| | - Kristala L J Prather
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge 02142, USA
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Almeida BC, Kaczmarek JA, Figueiredo PR, Prather KLJ, Carvalho ATP. Transcription factor allosteric regulation through substrate coordination to zinc. NAR Genom Bioinform 2021; 3:lqab033. [PMID: 33987533 PMCID: PMC8092373 DOI: 10.1093/nargab/lqab033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 03/30/2021] [Accepted: 04/08/2021] [Indexed: 11/14/2022] Open
Abstract
The development of new synthetic biology circuits for biotechnology and medicine requires deeper mechanistic insight into allosteric transcription factors (aTFs). Here we studied the aTF UxuR, a homodimer of two domains connected by a highly flexible linker region. To explore how ligand binding to UxuR affects protein dynamics we performed molecular dynamics simulations in the free protein, the aTF bound to the inducer D-fructuronate or the structural isomer D-glucuronate. We then validated our results by constructing a sensor plasmid for D-fructuronate in Escherichia coli and performed site-directed mutagenesis. Our results show that zinc coordination is necessary for UxuR function since mutation to alanines prevents expression de-repression by D-fructuronate. Analyzing the different complexes, we found that the disordered linker regions allow the N-terminal domains to display fast and large movements. When the inducer is bound, UxuR can sample an open conformation with a more pronounced negative charge at the surface of the N-terminal DNA binding domains. In opposition, in the free and D-glucuronate bond forms the protein samples closed conformations, with a more positive character at the surface of the DNA binding regions. These molecular insights provide a new basis to harness these systems for biological systems engineering.
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Affiliation(s)
- Beatriz C Almeida
- CNC-Center for Neuroscience and Cell Biology, Institute for Interdisciplinary Research (IIIUC), University of Coimbra, 3004-504 Coimbra, Portugal
| | - Jennifer A Kaczmarek
- MIT-Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Pedro R Figueiredo
- CNC-Center for Neuroscience and Cell Biology, Institute for Interdisciplinary Research (IIIUC), University of Coimbra, 3004-504 Coimbra, Portugal
| | - Kristala L J Prather
- MIT-Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Alexandra T P Carvalho
- CNC-Center for Neuroscience and Cell Biology, Institute for Interdisciplinary Research (IIIUC), University of Coimbra, 3004-504 Coimbra, Portugal
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Kerscher P, Kaczmarek JA, Head SE, Ellis ME, Seeto WJ, Kim J, Bhattacharya S, Suppiramaniam V, Lipke EA. Direct Production of Human Cardiac Tissues by Pluripotent Stem Cell Encapsulation in Gelatin Methacryloyl. ACS Biomater Sci Eng 2016; 3:1499-1509. [PMID: 33429637 DOI: 10.1021/acsbiomaterials.6b00226] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Direct stem cell encapsulation and cardiac differentiation within supporting biomaterial scaffolds are critical for reproducible and scalable production of the functional human tissues needed in regenerative medicine and drug-testing applications. Producing cardiac tissues directly from pluripotent stem cells rather than assembling tissues using pre-differentiated cells can eliminate multiple cell-handling steps that otherwise limit the potential for process automation and production scale-up. Here we asked whether our process for forming 3D developing human engineered cardiac tissues using poly(ethylene glycol)-fibrinogen hydrogels can be extended to widely used and printable gelatin methacryloyl (GelMA) hydrogels. We demonstrate that low-density GelMA hydrogels can be formed rapidly using visible light (<1 min) and successfully employed to encapsulate human induced pluripotent stem cells while maintaining high cell viability. Resulting constructs had an initial stiffness of approximately 220 Pa, supported tissue growth and dynamic remodeling, and facilitated high-efficiency cardiac differentiation (>70%) to produce spontaneously contracting GelMA human engineered cardiac tissues (GEhECTs). GEhECTs initiated spontaneous contractions on day 8 of differentiation, with synchronicity, frequency, and velocity of contraction increasing over time, and displayed developmentally appropriate temporal changes in cardiac gene expression. GEhECT-dissociated cardiomyocytes displayed well-defined and aligned sarcomeres spaced at 1.85 ± 0.1 μm and responded appropriately to drug treatments, including the β-adrenergic agonist isoproterenol and antagonist propranolol, as well as to outside pacing up to 3.0 Hz. Overall results demonstrate that GelMA is a suitable biomaterial for the production of developing cardiac tissues and has the potential to be employed in scale-up production and bioprinting of GEhECTs.
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Affiliation(s)
- Petra Kerscher
- Department of Chemical Engineering, Auburn University, 212 Ross Hall, Auburn, Alabama 36849, United States
| | - Jennifer A Kaczmarek
- Department of Chemical Engineering, Auburn University, 212 Ross Hall, Auburn, Alabama 36849, United States
| | - Sara E Head
- Department of Chemical Engineering, Auburn University, 212 Ross Hall, Auburn, Alabama 36849, United States
| | - Morgan E Ellis
- Department of Chemical Engineering, Auburn University, 212 Ross Hall, Auburn, Alabama 36849, United States
| | - Wen J Seeto
- Department of Chemical Engineering, Auburn University, 212 Ross Hall, Auburn, Alabama 36849, United States
| | - Joonyul Kim
- Proximity Biosciences LLC, Auburn, Alabama 36832, United States
| | - Subhrajit Bhattacharya
- Drug Discovery and Development, Harrison School of Pharmacy, Auburn University, 2316 Walker Building, Auburn, Alabama 36829, United States
| | - Vishnu Suppiramaniam
- Drug Discovery and Development, Harrison School of Pharmacy, Auburn University, 2316 Walker Building, Auburn, Alabama 36829, United States
| | - Elizabeth A Lipke
- Department of Chemical Engineering, Auburn University, 212 Ross Hall, Auburn, Alabama 36849, United States
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