Protein Engineering of Deoxynucleoside Kinase from Lactobacillus acidophilus: Effect of Site-Directed Mutagenesis on Microbial Growth

  • Park, Inshik ;
  • Kim, Eun-Ae ;
  • Bang, Keuk-Seung ;
  • Kim, Seok-Hwan ;
  • Kim, Gi-Nahm ;
  • Lee, Min-Kyung ;
  • Kil, Ji-Oeun
  • Published : 2001.03.01


Deoxynucleoside kinases exist as heterodimeric pairs specific for deoxyadenosine/deoxyguanosine kinase (dAK/dGK) and deoxyadenosine/deoxycytidine kinase (dAK/dCK). The aspartic acid-84 in dGK was mutated to alanine, asparagine and glutamic acid by site-directed mutagenesis. The mutation resulted in a drastic decease in dGK activity compared to the unmodified cloned enzyme while it increased production of dAK activity. The mutated dak/dgk genes, which synthesize tandem deoxyadenosine/deoxyguanosine kinase, were inserted back to the Lactobacillus acidophilus and Lactococcus lactis by electroporation to determine the effect of site-directed mutation of he enzymes on the microbial growth. However, no significant change was observed in cell growth and lactic acid production between wild type and mutant lactic acid bacteria.


deoxyguanosine kinase;site-directed mutagenesis;electroporation;Lactobacillus acidophilus