The Sac10b Homolog in Methanococcus maripaludis Binds DNA at Specific Sites
The Sac10b Homolog in Methanococcus maripaludis Binds DNA at Specific Sites
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马里帕鲁迪斯甲烷球菌中的 Sac10b 同源物在特定位点结合 DNA
DOI：
10.1128/jb.01534-08
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发表时间：
2009-04-01
影响因子：
3.2
通讯作者：
Huang, Li
中科院分区：
文献类型：
--
作者：
Liu, Yuchen;Guo, Li;Huang, Li
Sac 10 b蛋白家族，也称为Alba，广泛分布于海洋生物中。Sac 10 b同源物在嗜热硫化叶菌属中非常丰富。它们以高亲和力结合DNA和RNA，而没有序列特异性，它们的生理功能仍然没有完全了解。海洋甲烷球菌（Methanococcus maripaludis）是Sac 10 b家族的嗜温成员。Mma 10 b并不丰富，仅占总细胞蛋白的约0.01%。在最适生长温度附近的基本培养基中，mma 10 b的破坏导致突变体生长不良，但在丰富培养基中的生长没有可检测的影响。定量蛋白质组学、真实的时间反转录-PCR和酶分析显示，参与CO2同化和其他活动的一些基因的表达水平在Δ mma 10 b突变体中发生了变化。染色质免疫沉淀表明Mma 10 b在体内与18-bp DNA结合基序直接相关。电泳迁移率变动分析和DNA酶I足迹法证实，Mma 10 b优先结合特定序列的DNA与明显的Kd在100 nM范围内。这些结果表明，Mma 10 b在嗜温甲烷球菌中的生理作用与嗜热菌中的同源物有很大的不同。
ABSTRACT The Sac10b protein family, also known as Alba, is widely distributed in Archaea. Sac10b homologs in thermophilic Sulfolobus species are very abundant. They bind both DNA and RNA with high affinity and without sequence specificity, and their physiological functions are still not fully understood. Mma10b from the euryarchaeote Methanococcus maripaludis is a mesophilic member of the Sac10b family. Mma10b is not abundant and constitutes only ∼0.01% of the total cellular protein. Disruption of mma10b resulted in poor growth of the mutant in minimal medium at near the optimal growth temperature but had no detectable effect on growth in rich medium. Quantitative proteomics, real time reverse transcription-PCR, and enzyme assays revealed that the expression levels of some genes involved in CO2 assimilation and other activities were changed in the Δmma10b mutant. Chromatin immunoprecipitation suggested a direct association of Mma10b with an 18-bp DNA binding motif in vivo. Electrophoretic mobility shift assays and DNase I footprinting confirmed that Mma10b preferentially binds specific sequences of DNA with an apparent K d in the 100 nM range. These results suggested that the physiological role of Mma10b in the mesophilic methanococci is greatly diverged from that of homologs in thermophiles.