Bacterial nucleoid dynamics:: oxidative stress response in Staphylococcus aureus
Bacterial nucleoid dynamics:: oxidative stress response in Staphylococcus aureus
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DOI：
10.1111/j.1365-2443.2006.00949.x
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发表时间：
2006-04-01
期刊：
影响因子：
2.1
通讯作者：
Takeyasu, K
中科院分区：
文献类型：
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作者：
Morikawa, K;Ohniwa, RL;Takeyasu, K
应用单分子成像技术-原子力显微镜（AFM）对金黄色葡萄球菌的基因组结构进行了研究。对盖玻片上的葡萄球菌细胞进行温和的裂解程序，该程序保持了大肠杆菌中的基本结构单元。发现类核由直径为80和40 nm的纤维状结构组成。这一特性与E.大肠杆菌类核。然而，E.大肠杆菌类核在进入固定相时发生结构动态变化，形成高度致密的类核;金黄色葡萄球菌的类核在正常生长条件下从未经历过如此紧密的压实。生物信息学分析表明，这是由于缺乏调节类核蛋白Dps表达的IHF，而Dps是E.杆菌另一方面，在氧化条件下，MrgA（葡萄球菌Dps同源物）被过度表达，并检测到类核的剧烈压缩。敲除编码转录因子（perR）的基因的突变体组成型表达mrgA，并且其类核在没有氧化应激的情况下被压缩。Dps/MrgA表达的调控机制及其生物学意义被推测与类核压实有关。
A single-molecule-imaging technique, atomic force microscopy (AFM) was applied to the analyses of the genome architecture of Staphylococcus aureus. The staphylococcal cells on a cover glass were subjected to a mild lysis procedure that had maintained the fundamental structural units in Escherichia coli. The nucleoids were found to consist of fibrous structures with diameters of 80 and 40 nm. This feature was shared with the E. coli nucleoid. However, whereas the E. coli nucleoid dynamically changed its structure to a highly compacted one towards the stationary phase, the S. aureus nucleoid never underwent such a tight compaction under a normal growth condition. Bioinformatic analysis suggested that this was attributable to the lack of IHF that regulate the expression of a nucleoid protein, Dps, required for nucleoid compaction in E. coli. On the other hand, under oxidative conditions, MrgA (a staphylococcal Dps homolog) was over-expressed and a drastic compaction of the nucleoid was detected. A knock-out mutant of the gene encoding the transcription factor (perR) constitutively expressed mrgA, and its nucleoid was compacted without the oxidative stresses. The regulatory mechanisms of Dps/MrgA expression and their biological significance were postulated in relation to the nucleoid compaction.