Barbosa T M, Levy S B
Center for Adaptation Genetics and Drug Resistance and the Departments of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts 02111, USA.
J Bacteriol. 2000 Jun;182(12):3467-74. doi: 10.1128/JB.182.12.3467-3474.2000.
In Escherichia coli, the MarA protein controls expression of multiple chromosomal genes affecting resistance to antibiotics and other environmental hazards. For a more-complete characterization of the mar regulon, duplicate macroarrays containing 4,290 open reading frames of the E. coli genome were hybridized to radiolabeled cDNA populations derived from mar-deleted and mar-expressing E. coli. Strains constitutively expressing MarA showed altered expression of more than 60 chromosomal genes: 76% showed increased expression and 24% showed decreased expression. Although some of the genes were already known to be MarA regulated, the majority were newly determined and belonged to a variety of functional groups. Some of the genes identified have been associated with iron transport and metabolism; other genes were previously known to be part of the soxRS regulon. Northern blot analysis of selected genes confirmed the results obtained with the macroarrays. The findings reveal that the mar locus mediates a global stress response involving one of the largest networks of genes described.
在大肠杆菌中，MarA蛋白控制着多个染色体基因的表达，这些基因影响着对抗生素和其他环境危害的抗性。为了更全面地描述mar操纵子，将包含大肠杆菌基因组4290个开放阅读框的重复宏阵列与来自mar缺失和mar表达的大肠杆菌的放射性标记cDNA群体进行杂交。组成型表达MarA的菌株显示出60多个染色体基因的表达发生改变：76%的基因表达增加，24%的基因表达减少。虽然其中一些基因已知受MarA调控，但大多数是新确定的，并且属于各种功能组。鉴定出的一些基因与铁运输和代谢有关；其他基因以前已知是soxRS操纵子的一部分。对选定基因的Northern印迹分析证实了宏阵列获得的结果。这些发现表明，mar位点介导了一种全局应激反应，涉及所描述的最大基因网络之一。
