Assessment of expression of Leloir pathway genes in wild-type galactose-fermenting Streptococcus thermophilus by real-time PCR
Assessment of expression of Leloir pathway genes in wild-type galactose-fermenting Streptococcus thermophilus by real-time PCR
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DOI：
10.1007/s00217-014-2286-9
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发表时间：
2014-11-01
影响因子：
3.3
通讯作者：
Singh, Rameshwar
中科院分区：
文献类型：
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作者：
Anbukkarasi, Kaliyaperumal;Nanda, Dhiraj Kumar;Singh, Rameshwar
在这项研究中，四种半乳糖阳性（Gal（+））嗜热链球菌菌株即。使用 AJM、JM1、KM3 和 AUKD8 以及一种半乳糖阴性 (Gal(-)) 嗜热链球菌 NCDC 218，使用长程 PCR 来表征 Leloir 途径基因的组织，并使用实时 PCR 在不同糖存在的情况下研究这些基因的表达。长程 PCR 结果表明，Gal(+) 和 Gal(-) 分离株（gal-lac 基因序列 (galRKTEM-lacSZ)）都是保守的，包括单个基因的大小。三个Gal(+)分离株(AJM、JM1和KM3)的启动子序列在galR的-28区域具有单碱基对缺失，并且在-9盒galK区域具有C至T替换。相反，Gal(+) AUKD8 在 galR 的前面的 -25 区域具有 A 至 T 的取代。在半乳糖存在下生长的 galK 和 galM 的表达在 AJM 的情况下显着较高（分别是 30 倍和 7.6 倍），其次是 KM3 和 JM1。此外，galR、galT 和 galE 在半乳糖中的表达高于在乳糖和葡萄糖培养基中的表达。本研究对野生Gal(+)嗜热链球菌中Leloir途径基因的表达提供了初步的认识，进一步的研究可能会为半乳糖操纵子在半乳糖代谢中的作用提供更多的线索。
In this study, four galactose-positive (Gal(+)) Streptococcus thermophilus strains viz. AJM, JM1, KM3 and AUKD8 and one galactose-negative (Gal(-)) S. thermophilus NCDC 218 were used to characterize the organization of Leloir pathway genes using long-range PCR, and expression of these genes were studied using real-time PCR, in presence of different sugars. Long-range PCR results showed that both Gal(+) and Gal(-) isolates, the gal-lac gene order (galRKTEM-lacSZ), are conserved including the size of individual genes. The promoter sequence of the three Gal(+) isolates (AJM, JM1 and KM3) possessed single base pair deletion at -28 region of galR and C to T substitution at -9 box galK region. In contrast, Gal(+) AUKD8 had A to T substitution at preceding -25 region of galR. The expression of galK and galM grown in the presence of galactose was significantly higher in case of AJM (30- and 7.6-fold, respectively), followed by KM3 and JM1. In addition, galR, galT and galE showed higher expression in galactose, than in lactose and glucose medium. This study gives a preliminary idea on Leloir pathway gene expression in wild Gal(+) S. thermophilus, and further studies may throw more light on the role of gal-lac operon in galactose metabolism.