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Alleviation of temperature-sensitive secretion defect of Pseudomonas fluorescens ATP-binding cassette (ABC) transporter, TliDEF, by a change of single amino acid in the ABC protein, TliD

Eom, Gyeong Tae, Oh, Joon Young, Park, Ji Hyun, Lim, Hye Jin, Lee, So Jeong, Kim, Eun Young, Choi, Ji-Eun, Jegal, Jonggeon, Song, Bong Keun, Yu, Ju-Hyun, Song, Jae Kwang
Journal of bioscience and bioengineering 2016 v.122 no.3 pp. 283-286
ABC transporters, Escherichia coli, Pseudomonas fluorescens, amino acids, carboxylic ester hydrolases, mutagenesis, mutants, point mutation, polymerase chain reaction, secretion, temperature
An ABC transporter, TliDEF, from Pseudomonas fluorescens SIK W1, mediates the secretion of its cognate lipase, TliA, in a temperature-dependent secretion manner; the TliDEF-mediated secretion of TliA was impossible at the temperatures over 33°C. To isolate a mutant TliDEF capable of secreting TliA at 35°C, the mutagenesis of ABC protein (TliD) was performed. The mutated tliD library where a random point mutation was introduced by error-prone PCR was coexpressed with the wild-type tliE, tliF and tliA in Escherichia coli. Among approximately 10,000 colonies of the tliD library, we selected one colony that formed transparent halo on LB-tributyrin plates at 35°C. At the growth temperature of 35°C, the selected mutant TliD showed 1.75 U/ml of the extracellular lipase activity, while the wild-type TliDEF did not show any detectable lipase activity in the culture supernatant of E. coli. Moreover, the mutant TliD also showed higher level of TliA secretion than the wild-type TliDEF at other culture temperatures, 20°C, 25°C and 30°C. The mutant TliD had a single amino acid change (Ser287Pro) in the predicted transmembrane region in the membrane domain of TliD, implying that the corresponding region of TliD was important for causing the temperature-dependent secretion of TliDEF. These results suggested that the property of ABC transporter could be changed by the change of amino acid in the ABC protein.