Cloning And Overexpression Of Deoxyribonuclease (Nucb) From Bacillus Licheniformis In E. Coli Expression System
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Date
2015-08
Authors
Leong, Xin Yun
Journal Title
Journal ISSN
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Publisher
Universiti Sains Malaysia
Abstract
NucB deoxyribonuclease of Bacillus licheniformis ATCC 14580 is expected to disperse the microbial biofilm which is a problematic biological structure notorious for causing numerous complications in a variety of industrial and healthcare context due to its 94% similarity with that of the marine-isolated B. licheniformis strain EI-34-6 in which the latter has demonstrated the ability to rapidly break up the biofilms formed by both Gram-positive and Gram-negative bacteria. It is an extracellular nuclease encoded by the 429 base pairs NucB gene and assuming the size of 15.332 kDa. Its mechanism of action in relation to biofilm dispersal is thought to be the digestion of one important component of the biofilm extracellular polymeric substances (EPS) responsible for the biofilm structural integrity namely the extracellular DNA (eDNA). Digestion of the eDNA causes loosening of the EPS matrix leading to total removal of the biofilm. Besides, the Bacillus NucB was claimed to have higher potency compared to other nucleases including DNase I in degrading the eDNA. This study focused to clone and overexpress the NucB deoxyribonuclease using the pET vector and E. coli expression system in which the recombinant protein will be tagged with the fusion partner, a 6× polyhistidine at the carboxyl terminal to facilitate detection and purification. The recombinant construct was first formed and subsequently transformed into the E.coli expression host for expression using both conventional IPTG induction and autoinduction. The difference in the expression level between the induced and the
uninduced samples was initially observed through SDS PAGE study. The final Western blot analysis showed the presence of the His-tagged target protein.
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Keywords
Biofilm