Park Soon-Nang, Lim Yun Kyong, Choi Mi-Hwa, Cho Eugene, Bang Iel Soo, Kim Jung Min, Ahn Sug-Joon, Kook Joong-Ki
Korean Collection for Oral Microbiology and Department of Oral Biochemistry, School of Dentistry, Chosun University, Gwangju, 61452, Republic of Korea.
Department of Oral Microbiology, School of Dentistry, Chosun University, Gwangju, 61452, Republic of Korea.
Curr Microbiol. 2018 Jan;75(1):11-19. doi: 10.1007/s00284-017-1344-5. Epub 2017 Aug 29.
Triterpenoid saponin derivatives oleanolic acid (OA) and ursolic acid (UA), but not betulinic acid (BA), were previously found to have strong antimicrobial activity against Streptococcus mutans. OA and UA inhibited the transcription of genes related to peptidoglycan biosynthesis, thereby preventing bacterial growth. However, it is not clear whether this is the only pathway involved in the antimicrobial activity of these compounds against S. mutans. Therefore, we used quantitative real-time PCR (qPCR) and microarray analyses to examine the expression of genes related to essential metabolic pathways in S. mutans UA159 following incubation with OA, UA, or BA. An oligonucleotide array consisting of 5363 probes was designed to survey 1928 of the 1963 genes in the genome of S. mutans UA159. Genes that showed >2-fold changes in expression in response to the treatment conditions were annotated, and selected target genes involved in central metabolism were analyzed by qPCR. Microarray analysis confirmed that the gene expression patterns of the OA- and UA-treated cells differed from that of the BA-treated culture, indicating differences in the antimicrobial mechanism. In particular, the expression of pfk and pykF, coding for glycolysis regulatory proteins phosphofructokinase and pyruvate kinase, respectively, were significantly decreased in the OA and UA groups (P < 0.05), as were genes involved in fatty acid and amino acid synthesis. In addition, the microarray analysis confirmed previous qPCR results showing that peptidoglycan synthesis is down-regulated in the OA- and UA-treated groups. OA and UA also appear to decrease the generation of organic acids by S. mutans UA159, which would have an anticaries effect. Overall, these findings suggest that OA and UA affect multiple genes involved in the central metabolism of S. mutans, with inhibition of glycolysis, fatty acid synthesis, amino acid synthesis, and peptidoglycan synthesis, all contributing to their antimicrobial activity.
三萜皂苷衍生物齐墩果酸（OA）和熊果酸（UA），而非桦木酸（BA），此前被发现对变形链球菌具有强大的抗菌活性。OA和UA抑制了与肽聚糖生物合成相关基因的转录，从而阻止细菌生长。然而，尚不清楚这是否是这些化合物对变形链球菌抗菌活性的唯一作用途径。因此，我们使用定量实时PCR（qPCR）和微阵列分析来检测变形链球菌UA159在与OA、UA或BA孵育后与基本代谢途径相关基因的表达。设计了一个由5363个探针组成的寡核苷酸阵列，以检测变形链球菌UA159基因组中1963个基因中的1928个。对在处理条件下表达变化超过2倍的基因进行注释，并通过qPCR分析参与中心代谢的选定靶基因。微阵列分析证实，OA和UA处理细胞的基因表达模式与BA处理培养物的不同，表明抗菌机制存在差异。特别是，分别编码糖酵解调节蛋白磷酸果糖激酶和丙酮酸激酶的pfk和pykF的表达在OA和UA组中显著降低（P<0.05），参与脂肪酸和氨基酸合成的基因也是如此。此外，微阵列分析证实了先前的qPCR结果，表明在OA和UA处理组中肽聚糖合成下调。OA和UA似乎还能减少变形链球菌UA159产生的有机酸，这将具有防龋作用。总体而言，这些发现表明OA和UA影响变形链球菌中心代谢中涉及的多个基因，对糖酵解、脂肪酸合成、氨基酸合成和肽聚糖合成的抑制都有助于它们的抗菌活性。
