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Choi JW, Song NE, Hong SP, Rhee YK, Hong HD, Cho CW. Engineering Bacillus subtilis J46 for efficient utilization of galactose through adaptive laboratory evolution. AMB Express 2024; 14:14. [PMID: 38282124 PMCID: PMC10822834 DOI: 10.1186/s13568-024-01666-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Accepted: 01/08/2024] [Indexed: 01/30/2024] Open
Abstract
Efficient utilization of galactose by microorganisms can lead to the production of valuable bio-products and improved metabolic processes. While Bacillus subtilis has inherent pathways for galactose metabolism, there is potential for enhancement via evolutionary strategies. This study aimed to boost galactose utilization in B. subtilis using adaptive laboratory evolution (ALE) and to elucidate the genetic and metabolic changes underlying the observed enhancements. The strains of B. subtilis underwent multiple rounds of adaptive laboratory evolution (approximately 5000 generations) in an environment that favored the use of galactose. This process resulted in an enhanced specific growth rate of 0.319 ± 0.005 h-1, a significant increase from the 0.03 ± 0.008 h-1 observed in the wild-type strains. Upon selecting the evolved strain BSGA14, a comprehensive whole-genome sequencing revealed the presence of 63 single nucleotide polymorphisms (SNPs). Two of them, located in the coding sequences of the genes araR and glcR, were found to be the advantageous mutations after reverse engineering. The strain with these two accumulated mutations, BSGALE4, exhibited similar specific growth rate on galactose to the evolved strain BSGA14 (0.296 ± 0.01 h-1). Furthermore, evolved strain showed higher productivity of protease and β-galactosidase in mock soybean biomass medium. ALE proved to be a potent tool for enhancing galactose metabolism in B. subtilis. The findings offer valuable insights into the potential of evolutionary strategies in microbial engineering and pave the way for industrial applications harnessing enhanced galactose conversion.
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Affiliation(s)
- Jae Woong Choi
- Research Group of Traditional Food, Korea Food Research Institute, 245, Nongsaengmyeong-ro, Iseo-myeon, Wanju-gun, 55365, Republic of Korea
| | - Nho-Eul Song
- Research Group of Traditional Food, Korea Food Research Institute, 245, Nongsaengmyeong-ro, Iseo-myeon, Wanju-gun, 55365, Republic of Korea
| | - Sang-Pil Hong
- Research Group of Traditional Food, Korea Food Research Institute, 245, Nongsaengmyeong-ro, Iseo-myeon, Wanju-gun, 55365, Republic of Korea
| | - Young Kyoung Rhee
- Research Group of Traditional Food, Korea Food Research Institute, 245, Nongsaengmyeong-ro, Iseo-myeon, Wanju-gun, 55365, Republic of Korea
| | - Hee-Do Hong
- Research Group of Traditional Food, Korea Food Research Institute, 245, Nongsaengmyeong-ro, Iseo-myeon, Wanju-gun, 55365, Republic of Korea
| | - Chang-Won Cho
- Research Group of Traditional Food, Korea Food Research Institute, 245, Nongsaengmyeong-ro, Iseo-myeon, Wanju-gun, 55365, Republic of Korea.
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Jain D, Narayanan N, Nair DT. Plasticity in Repressor-DNA Interactions Neutralizes Loss of Symmetry in Bipartite Operators. J Biol Chem 2015; 291:1235-42. [PMID: 26511320 DOI: 10.1074/jbc.m115.689695] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Indexed: 11/06/2022] Open
Abstract
Transcription factor-DNA interactions are central to gene regulation. Many transcription factors regulate multiple target genes and can bind sequences that do not conform strictly to the consensus. To understand the structural mechanism utilized by the transcription regulators to bind diverse target sequences, we have employed the repressor AraR from Bacillus subtilis as a model system. AraR is known to bind to eight different operator sites in the bacterial genome. Although there are differences in the sequences of four of these operators, ORE1, ORX1, ORA1, and ORR3, the AraR-DNA binding domain (AraR-DBD) as well as full-length AraR unexpectedly binds to each of these sequences with similar affinities as measured by fluorescence anisotropy experiments. We have determined crystal structures of AraR-DBD in complex with two different natural operators ORE1 and ORX1 up to 2.07 and 1.97 Å resolution, respectively. These structures were compared with the previously reported structures of AraR-DBD bound to two other natural operators (ORA1 and ORR3). Interactions of two molecules of AraR-DBD with the symmetric operator, ORE1, are identical, but their interaction with the non-symmetric operator ORX1 results in breakdown of the symmetry in protein-DNA interactions. The novel interactions observed are accompanied by local conformational change in the DNA. ChIP-sequencing (ChIP-Seq) data on other transcription factors has shown that they can bind to diverse targets, and hence the plasticity exhibited by AraR may be a general phenomenon. The ability of transcription factors to form alternate interactions may be important for employment in new functions and evolution of novel regulatory circuits.
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Affiliation(s)
- Deepti Jain
- From the Transcription Regulation Lab and the National Centre for Biological Sciences (NCBS-TIFR), UAS-GKVK Campus, Bellary Road, Bangalore 560065, and
| | - Naveen Narayanan
- the National Centre for Biological Sciences (NCBS-TIFR), UAS-GKVK Campus, Bellary Road, Bangalore 560065, and the Genomic Integrity and Plasticity Lab, Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone, Faridabad-Gurgaon Expressway, Bhankri Village, Faridabad 121001, Manipal University, Manipal, 576104 Karnataka, India
| | - Deepak T Nair
- the National Centre for Biological Sciences (NCBS-TIFR), UAS-GKVK Campus, Bellary Road, Bangalore 560065, and the Genomic Integrity and Plasticity Lab, Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone, Faridabad-Gurgaon Expressway, Bhankri Village, Faridabad 121001
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