Physiological function of the maltose operon regulator, MalR, in Lactococcus lactis.
Physiological function of the maltose operon regulator, MalR, in Lactococcus lactis.
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DOI：
10.1186/1471-2180-2-28
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发表时间：
2002-09-25
期刊：
影响因子：
4.2
通讯作者：
Rådström P
中科院分区：
文献类型：
--
作者：
Andersson U;Rådström P
乳酸乳球菌的麦芽糖代谢是由ATP依赖的通透酶系统启动的。细胞内麦芽糖的后续降解是通过Pi依赖性麦芽糖磷酸化酶和β-磷酸葡萄糖变位酶的协同作用进行的。在一些革兰氏阳性细菌中，麦芽糖代谢受麦芽糖操纵子调节子（MalR）调节，其属于LacI-GalR家族的转录调节子。在L.乳。本研究的目的是探讨麦芽糖受体蛋白在L.乳。A L.乳酸亚种乳酸菌突变体TMB 5004，在推定的MalR蛋白缺陷，生理特征。该突变体不能发酵麦芽糖，而其在葡萄糖和海藻糖上生长的能力不受影响。麦芽糖磷酸化酶和β-葡萄糖磷酸变位酶的活性在突变体中不受影响。然而，在野生型的特定麦芽糖摄取率，在其最低，五倍高于突变体。麦芽糖摄取的这种差异随着测定中麦芽糖浓度的增加而增加。根据氨基酸序列的相似性，推测MalR是LacI-GalR家族的转录调节因子。由于对麦芽糖转运的激活作用和对麦芽糖磷酸化酶和β-磷酸葡萄糖变位酶活性的影响，L.乳酸被认为是激活剂而不是抑制剂。
Maltose metabolism is initiated by an ATP-dependent permease system in Lactococcus lactis. The subsequent degradation of intracellular maltose is performed by the concerted action of Pi-dependent maltose phosphorylase and β-phosphoglucomutase. In some Gram-positive bacteria, maltose metabolism is regulated by a maltose operon regulator (MalR), belonging to the LacI-GalR family of transcriptional regulators. A gene presumed to encode MalR has been found directly downstream the maltose phosphorylase-encoding gene, malP in L. lactis. The purpose of this study was to investigate the physiological role of the MalR protein in maltose metabolism in L. lactis. A L. lactis ssp. lactis mutant, TMB5004, deficient in the putative MalR protein, was physiologically characterised. The mutant was not able to ferment maltose, while its capability to grow on glucose as well as trehalose was not affected. The activity of maltose phosphorylase and β-phosphoglucomutase was not affected in the mutant. However, the specific maltose uptake rate in the wild type was, at its lowest, five times higher than in the mutant. This difference in maltose uptake increased as the maltose concentration in the assay was increased. According to amino acid sequence similarities, the presumed MalR is a member of the LacI-GalR family of transcriptional regulators. Due to the suggested activating effect on maltose transport and absence of effect on the activities of maltose phosphorylase and β-phosphoglucomutase, MalR of L. lactis is considered rather as an activator than a repressor.
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影响因子：
4.8
作者：
Andersson, U;Levander, F;Rådström, P
通讯作者：
Rådström, P
影响因子：
2.8
作者：
Qian, N;Stanley, GA;Radstrom, P
通讯作者：
Radstrom, P
影响因子：
2.1
作者：
Schlösser, A;Weber, A;Schrempf, H
通讯作者：
Schrempf, H
影响因子：
3.5
作者：
INOUE, H;NOJIMA, H;OKAYAMA, H
通讯作者：
OKAYAMA, H
影响因子：
3.2
作者：
LAW, J;BUIST, G;LEENHOUTS, K
通讯作者：
LEENHOUTS, K