FtsZ filament dynamics at steady state: subunit exchange with and without nucleotide hydrolysis.
FtsZ filament dynamics at steady state: subunit exchange with and without nucleotide hydrolysis.
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DOI：
10.1021/bi8022653
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发表时间：
2009-07-21
期刊：
影响因子：
2.9
通讯作者：
Erickson, Harold P.
中科院分区：
文献类型：
--
作者：
Chen, Yaodong;Erickson, Harold P.
我们测量了稳态下 FtsZ 丝动力学的三个方面：GTP 水解速率、原丝之间的亚基交换以及稀释或过量 GDP 引起的分解。通过用铷替代钾，将钾浓度从 100 mM 增加到 500 mM，或者将镁浓度从 5 mM 增加到 20 mM，所有三个反应都会减慢。电子显微镜显示，在最快组装的条件下组装的聚合物主要是短的单链原丝，而在较慢的动力学条件下，原丝倾向于缔合成长的、细的束。我们认为，稳态下原丝之间的亚基交换涉及两种不同的机制：GTP 水解后亚基从原丝末端断裂或解离，以及与水解无关的亚基从原丝末端的可逆缔合和解离。这些回收亚基上的核苷酸交换可以使表面看起来直接交换到聚合物中。我们的一些观察结果表明，核苷酸交换可以发生在这些回收亚基上，但不能直接发生在 FtsZ 聚合物中。 L68W 突变体在 EDTA 缓冲液中证实了原丝的退火，但在 Mg 缓冲液中则不然，其中亚基的快速循环可能会掩盖退火的效果。我们还重新研究了稳态下 FtsZ 聚合物的核苷酸组成。我们发现，当 GTP 浓度 > 100 μM 时，GDP:GTP 比率为 50:50，显着高于之前报道的 20 μM GTP 时的 20:80 比率。
We have measured three aspects of FtsZ filament dynamics at steady state: rates of GTP hydrolysis, subunit exchange between protofilaments, and disassembly induced by dilution or excess GDP. All three reactions were slowed with an increase in the potassium concentration from 100 to 500 mM, via replacement of potassium with rubidium, or with an increase in the magnesium concentration from 5 to 20 mM. Electron microscopy showed that the polymers assembled under the conditions of fastest assembly were predominantly short, one-stranded protofilaments, whereas under conditions of slower dynamics, the protofilaments tended to associate into long, thin bundles. We suggest that exchange of subunits between protofilaments at steady state involves two separate mechanisms: fragmentation or dissociation of subunits from protofilament ends following GTP hydrolysis and reversible association and dissociation of subunits from protofilament ends independent of hydrolysis. Exchange of nucleotides on these recycling subunits could give the appearance of exchange directly into the polymer. Several of our observations suggest that exchange of nucleotide can take place on these recycling subunits, but not directly into the FtsZ polymer. Annealing of protofilaments was demonstrated for the L68W mutant in EDTA buffer but not in Mg buffer, where rapid cycling of subunits may obscure the effect of annealing. We also reinvestigated the nucleotide composition of FtsZ polymers at steady state. We found that the GDP:GTP ratio was 50:50 for concentrations of GTP > 100 μM, significantly higher than the 20:80 ratio previously reported at 20 μM GTP.
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DOI：
10.1073/pnas.90.3.1053
发表时间：
1993-02-01
影响因子：
11.1
作者：
MUKHERJEE, A;DAI, K;LUTKENHAUS, J
通讯作者：
LUTKENHAUS, J
影响因子：
56.9
作者：
Osawa, Masaki;Anderson, David E.;Erickson, Harold P.
通讯作者：
Erickson, Harold P.
影响因子：
3.4
作者：
Miraldi, Emily R.;Thomas, Peter J.;Romberg, Laura
通讯作者：
Romberg, Laura
影响因子：
1.2
作者：
Dajkovic, Alex;Lutkenhaus, Joe
通讯作者：
Lutkenhaus, Joe
影响因子：
4.8
作者：
Chen, Yaodong;Erickson, Harold P.
通讯作者：
Erickson, Harold P.