Chromosome organization by a conserved condensin-ParB system in the actinobacterium Corynebacterium glutamicum
Chromosome organization by a conserved condensin-ParB system in the actinobacterium Corynebacterium glutamicum
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DOI：
10.1038/s41467-020-15238-4
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发表时间：
2020-03-20
影响因子：
16.6
通讯作者：
Bramkamp, Marc
中科院分区：
文献类型：
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作者：
Boehm, Kati;Giacomelli, Giacomo;Bramkamp, Marc
高阶染色体的折叠和分离在生命的各个领域都受到严格的调控。在细菌中，关于类核组织调节机制和功能的细节仍然缺乏特征，特别是在非模式物种中。在这里，我们调查的作用，DNA分配蛋白ParB和SMC凝聚素复合物中的放线菌谷氨酸棒杆菌。染色体构象捕获揭示了SMC介导的长距离相互作用，围绕着聚集在复制起点（oriC）的10个着丝粒样parS位点。至少一个oriC近端parS位点是可靠的染色体分离所必需的。我们使用染色质免疫沉淀和光活化单分子定位显微镜显示形成不同的，依赖parS的ParB核蛋白亚群。我们进一步表明，SMC/ScpAB复合物，通过ParB在parS网站加载，介导染色体臂间接触（如先前在枯草芽孢杆菌中所示）。然而，MukBEF样SMC复合物MksBEFG不有助于染色体DNA折叠，相反，该复合物参与质粒维持并与极性oriC-系留因子DivIVA相互作用。我们的研究结果补充了目前的ParB-SMC/ScpAB串扰模型，并表明一些凝聚素复合物进化的功能，显然是从染色体折叠解耦。
Higher-order chromosome folding and segregation are tightly regulated in all domains of life. In bacteria, details on nucleoid organization regulatory mechanisms and function remain poorly characterized, especially in non-model species. Here, we investigate the role of DNA-partitioning protein ParB and SMC condensin complexes in the actinobacterium Corynebacterium glutamicum. Chromosome conformation capture reveals SMC-mediated long-range interactions around ten centromere-like parS sites clustered at the replication origin (oriC). At least one oriC-proximal parS site is necessary for reliable chromosome segregation. We use chromatin immunoprecipitation and photoactivated single-molecule localization microscopy to show the formation of distinct, parS-dependent ParB-nucleoprotein subclusters. We further show that SMC/ScpAB complexes, loaded via ParB at parS sites, mediate chromosomal inter-arm contacts (as previously shown in Bacillus subtilis). However, the MukBEF-like SMC complex MksBEFG does not contribute to chromosomal DNA-folding; instead, this complex is involved in plasmid maintenance and interacts with the polar oriC-tethering factor DivIVA. Our results complement current models of ParB-SMC/ScpAB crosstalk and show that some condensin complexes evolved functions that are apparently uncoupled from chromosome folding.