Escherichia coli DNA glycosylase Mug: a growth-regulated enzyme required for mutation avoidance in stationary-phase cells.
Escherichia coli DNA glycosylase Mug: a growth-regulated enzyme required for mutation avoidance in stationary-phase cells.
复制标题
大肠杆菌 DNA 糖基化酶 Mug：稳定期细胞避免突变所需的生长调节酶。
DOI：
10.1046/j.1365-2958.2001.02559.x
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发表时间：
2001
影响因子：
3.6
通讯作者：
Bhagwat,AS
中科院分区：
文献类型：
--
作者：
Mokkapati,SK;FernándezdeHenestrosa,AR;Bhagwat,AS
TheEscherichia coliDNA glycosylase Mug excises 3,N4‐ethenocytosines (εC) and uracils from DNA, but its biological function is obscure. This is because εC is not found inE. coliDNA, and uracil‐DNA glycosylase (Ung), a distinct enzyme, is much more efficient at removing uracils from DNA than Mug. We find that Mug is overexpressed as cells enter stationary phase, and it is maintained at a fairly high level in resting cells. This is true of cells grown in rich or minimal media, and the principal regulation ofmugis at the level of mRNA. Although the expression ofmugis strongly dependent on the stationary‐phase sigma factor, σS, when cells are grown in minimal media, it shows only a modest dependence on σSwhen cells are grown in rich media. Whenmugcells are maintained in stationary phase for several days, they acquire many more mutations than theirmug+counterparts. This is true inungas well asung+cells, and a majority of new mutations may not be C to T. Our results show that the biological role of Mug parallels its expression in cells. It is expressed poorly in exponentially growing cells and has no apparent role in mutation avoidance in these cells. In contrast, Mug is fairly abundant in stationary‐phase cells and has an important anti‐mutator role at this stage of cell growth. Thus, Mug joins a very small coterie of DNA repair enzymes whose principal function is to avoid mutations in stationary‐phase cells.
