Tuned SMC Arms Drive Chromosomal Loading of Prokaryotic Condensin.
Tuned SMC Arms Drive Chromosomal Loading of Prokaryotic Condensin.
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DOI：
10.1016/j.molcel.2017.01.026
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发表时间：
2017-03-02
期刊：
影响因子：
16
通讯作者：
Gruber S
中科院分区：
文献类型：
--
作者：
Bürmann F;Basfeld A;Vazquez Nunez R;Diebold-Durand ML;Wilhelm L;Gruber S
SMC蛋白通过组织染色体DNA来支持生命各个领域的重要细胞过程。它们是由ATPase的“头”和“铰”二聚结构域和一个连接的螺旋线圈“臂”组成的。Kleisin亚单位与Kleisin亚基的结合形成了一个闭合的三元环，其47 nm长的SMC臂充当了∼捕获的屏障。在这里，我们揭示了细菌SMC臂的另一个更活跃的功能。使用高通量基因工程，我们在6-60纳米的范围内调整了手臂的大小，发现它只有在特定的长度范围内才能发挥功能，遵循周期性的模式。自然SMC序列反映了这些长度限制。具有不适当臂长或在臂中插入多肽的突变体有效地靶向染色体加载位置并水解三磷酸腺苷，但不能利用三磷酸腺苷水解酶将其重新定位到侧翼DNA上。我们认为，SMC ARM在核苷酸水解时执行力传递，以介导DNA捕获或环挤出。Bürmann等人指出，SMC短臂和长臂但不是中长SMC螺旋臂是具有不正确臂聚集在染色体上的功能性SMC复合体，SMC臂是将ATP水解酶与必要的DNA交易联系起来的功能单位，原核和真核SMC序列通过设计一系列具有更短或更长卷曲臂的SMC蛋白质来反映类似的周期长度限制。阐明手臂的超螺旋性质的关键作用。不正确的臂支持染色体靶向，但无法将ATP水解酶与染色体加载联系起来。SMC臂被认为是在核苷酸水解时实现力传递的。
SMC proteins support vital cellular processes in all domains of life by organizing chromosomal DNA. They are composed of ATPase “head” and “hinge“ dimerization domains and a connecting coiled-coil “arm.” Binding to a kleisin subunit creates a closed tripartite ring, whose ∼47-nm-long SMC arms act as barrier for DNA entrapment. Here, we uncover another, more active function of the bacterial Smc arm. Using high-throughput genetic engineering, we resized the arm in the range of 6–60 nm and found that it was functional only in specific length regimes following a periodic pattern. Natural SMC sequences reflect these length constraints. Mutants with improper arm length or peptide insertions in the arm efficiently target chromosomal loading sites and hydrolyze ATP but fail to use ATP hydrolysis for relocation onto flanking DNA. We propose that SMC arms implement force transmission upon nucleotide hydrolysis to mediate DNA capture or loop extrusion. Short and long but not intermediate-length Smc coiled-coil arms are functional Smc complexes with improper arms accumulate at chromosomal loading sites Smc arms are functional units linking ATP hydrolysis to an essential DNA transaction Pro- and eukaryotic SMC sequences reflect similar periodic length constraints By engineering a series of Smc proteins with shorter or longer coiled-coil arms, Bürmann et al. elucidate a critical role for the arms’ super-helical nature. Improper arms support chromosomal targeting but fail to link ATP hydrolysis to chromosomal loading. Smc arms are proposed to implement force transmission upon nucleotide hydrolysis.
影响因子：
3.7
作者：
White GE;Erickson HP
通讯作者：
Erickson HP