Algorithms for optimizing cross-overs in DNA shuffling

Author(s):  
Lu He ◽  
Alan M. Friedman ◽  
Chris Bailey-Kellogg
Keyword(s):  
2014 ◽  
Vol 14 (1) ◽  
pp. 8 ◽  
Author(s):  
Meng Li ◽  
Chunming Rao ◽  
Dening Pei ◽  
Lan Wang ◽  
Yonghong Li ◽  
...  

2007 ◽  
Vol 73 (16) ◽  
pp. 5292-5299 ◽  
Author(s):  
Tatsuya Tominaga ◽  
Yoshinori Hatakeyama

ABSTRACT Pediocin PA-1 is a member of the class IIa bacteriocins, which show antimicrobial effects against lactic acid bacteria. To develop an improved version of pediocin PA-1, reciprocal chimeras between pediocin PA-1 and enterocin A, another class IIa bacteriocin, were constructed. Chimera EP, which consisted of the C-terminal half of pediocin PA-1 fused to the N-terminal half of enterocin A, showed increased activity against a strain of Leuconostoc lactis isolated from a sour-spoiled dairy product. To develop an even more effective version of this chimera, a DNA-shuffling library was constructed, wherein four specific regions within the N-terminal half of pediocin PA-1 were shuffled with the corresponding sequences from 10 other class IIa bacteriocins. Activity screening indicated that 63 out of 280 shuffled mutants had antimicrobial activity. A colony overlay activity assay showed that one of the mutants (designated B1) produced a >7.8-mm growth inhibition circle on L. lactis, whereas the parent pediocin PA-1 did not produce any circle. Furthermore, the active shuffled mutants showed increased activity against various species of Lactobacillus, Pediococcus, and Carnobacterium. Sequence analysis revealed that the active mutants had novel N-terminal sequences; in active mutant B1, for example, the parental pediocin PA-1 sequence (KYYGNGVTCGKHSC) was changed to TKYYGNGVSCTKSGC. These new and improved DNA-shuffled bacteriocins could prove useful as food additives for inhibiting sour spoilage of dairy products.


2020 ◽  
Vol 11 (1) ◽  
pp. 7735-7745

Biotechnology is considered one of the most influential technologies in various areas of human life, including health, economics, and the environment. Protein engineering is one of the major biotechnology tools in the field of modification and advancement of biocatalysts capabilities. Among the most effective protein engineering methods, in particular, to improve the industrial strain capabilities, is the shuffling genome method. This study aimed to follow knowledge and biocatalysts engineering techniques based on DNA shuffling methods. In the first step, two procedures were followed (DES method and compatibility according to the concentration gradient of Diazinon) to obtain mutant strains. Acquired mutant strains from both methods were resistant to high concentrations of poison up to 3000 mg/L. The activity of these strains also demonstrated their elevated activity compared to parent samples. The highest activity was related to four strains IR1.G1, IR1.D8, IR1.D4, and IR1.D5, which were 0.234 U/ml, 0.1 U/ml, 0.098 U/ml, and 0.066 U/ml, respectively. The improved strain was obtained via the concentration gradient of the diazinon method (IRL1.G1 strain) in comparison with IRL1.D8 strain (owning highest activity through DES method) possesses excessive activity in 3000 mg/L concentration of Diazinon. The evaluated results of first-generation genome shuffling of strains (the first round of protoplast fusion) also indicated that those shuffled strains with the ability to grow in the vicinity of the toxin (3000 mg/L concentration of Diazinon) showed better activity than obtained mutated strains by both methods (concentration gradient of the toxin and the DES method). In the final stage, the best results were related to IRL1.F2, IRL1.F3, and IRL1.F1 shuffled strains with 0.541 mg/L, 0.523 mg/L, and 0.509 mg/L, respectively. The highest activity belonged to the IRL1.F2 genome shuffled strain (first round of protoplast fusion). This strain could grow in a high concentration of toxin, and also, the activity was increased 30, 3.6, and 2.3 times in comparison with the parent strain (IRL1), IRL.D8 mutant, and IRL1.G1, respectively.


2015 ◽  
Vol 49 (2) ◽  
pp. 253-259
Author(s):  
Q. -C. Jin ◽  
N. Shen ◽  
H. Yin ◽  
Y. Yang ◽  
Z. -H. Jin

2004 ◽  
Vol 70 (10) ◽  
pp. 6257-6263 ◽  
Author(s):  
Jyh-Shing Hsu ◽  
Yunn-Bor Yang ◽  
Chan-Hui Deng ◽  
Chia-Li Wei ◽  
Shwu-Huey Liaw ◽  
...  

ABSTRACT Deacetoxycephalosporin C synthase (expandase) from Streptomyces clavuligerus, encoded by cefE, is an important industrial enzyme for the production of 7-aminodeacetoxycephalosporanic acid from penicillin G. To improve the substrate specificity for penicillin G, eight cefE-homologous genes were directly evolved by using the DNA shuffling technique. After the first round of shuffling and screening, using an Escherichia coli ESS bioassay, four chimeras with higher activity were subjected to a second round. Subsequently, 20 clones were found with significantly enhanced activity. The kinetic parameters of two isolates that lack substrate inhibition showed 8.5- and 118-fold increases in the k cat/Km ratio compared to the S. clavuligerus expandase. The evolved enzyme with the 118-fold increase is the most active obtained to date anywhere. Our shuffling results also indicate the remarkable plasticity of the expandase, suggesting that more-active chimeras might be achievable with further rounds.


2015 ◽  
Vol 79 ◽  
pp. 965-970 ◽  
Author(s):  
Pei Yao ◽  
Yongjun Lin ◽  
Gaobing Wu ◽  
Yulin Lu ◽  
Tao Zhan ◽  
...  

Immunotherapy ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 951-969
Author(s):  
Zhitao Li ◽  
Jia Ding ◽  
Xiuyun Zhao ◽  
Gaofu Qi

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