Streptococcus salivarius의 요소분해효소 유전자 변이에 관한 연구
VARIATION OF UREASE GENES(ureC) FROM Streptococcus salivarius
최혜진, 이진용, 이영규,
소속 상세정보
최혜진 ( ) - 경희대학교 치과대학 치과보존학교실
이진용 ( ) - 경희대학교 치과대학 치과보존학교실
이영규 ( ) - 경희대학교 치과대학 치과보존학교실
KMID : 0362319990240040535
Abstract
Urease of Streptococcus salivarius is believed to play a critical role in bacterial ecology and pH homeostasis in the mouth, and consequently affect the pathogenesis of dental caries and periodontal diseases. Expression of the urease gene is greatly enhanced by low pH, excess of carbohydrate, and faster growth. It was observed that urease activity of the strains of S. salivarius that exhibited no or low urease activity was not increased even in low pH conditions. In this study, it was hypothesized that the urease gene of the strains is absent, defected, or greatly changed by genetic recombination. In order to prove this hypothesis, chromosomes were obtained from 28 S. salivarius strains which had been isolated from normal teeth and carious lesions, subjected to polymerase chain reaction(PCR) using primers encoding highly conserved sequence from ureC, and then the obtained PCR products were compared.
The results were as follows:
1. After PCR, the strains genereated either one of 0.54- and 1.3-kbp PCR products, or none.
2. All 16 strains having a higher urease activity(>50㎛mol/min/mg) produced 0.54-kbp PCR products.
3. Twelve strains without urease activity and with a lower urease activity(<50㎛mol/min/mg) yield either one of 0.54 and 1.3-kbp PCR products, or none.
4. The DNA sequence of the 0.54-kbp PCR product (pCAP^(5)-0. 54) exhibited 95% identity to the ureC of S.salivarius 57.1; 30bp were found to be different, which led to difference of only 2 amino acids in the sequence.
5. The DNA sequence of the 1.3-kbp PCR product (pCAP^(5)-1.3) was found to be highly homologous to the aminopeptidase C gene of Streptococcus thetmrophilus.
Overall results indicate that there are considerable variations of the urease genes from S. salivarius strains and the variations may affect the ureolytic activity of the bacteria directly or indirectly.
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