Biphasic character of ribosomal translocation and non-Michaelis-Menten kinetics of translation

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	Biphasic character of ribosomal translocation and non-Michaelis-Menten kinetics of translation
	Xie, P
刊名	PHYSICAL REVIEW E
	2014
卷号	90 期号:6
ISSN号	1539-3755
通讯作者	Xie, P (reprint author), Chinese Acad Sci, Inst Phys, Key Lab Soft Matter Phys, Beijing 100190, Peoples R China.
中文摘要	We study theoretically the kinetics of mRNA translocation in the wild-type (WT) Escherichia coli ribosome, which is composed of a small 30S and large 50S subunit, and the ribosomes with mutations to some intersubunit bridges such as B1a, B4, B7a, and B8. The theoretical results reproduce well the available in vitro experimental data on the biphasic kinetics of the forward mRNA translocation catalyzed by elongation factor G (EF-G) hydrolyzing GTP, which can be best fit by the sum of two exponentials, and the monophasic kinetics of the spontaneous reverse mRNA translocation in the absence of the elongation factor, which can be best fit by a single-exponential function, in both the WT and mutant ribosomes. We show that both the mutation-induced increase in the maximal rate of the slow phase for the forward mRNA translocation and that in the rate of the spontaneous reverse mRNA translocation result from a reduction in the intrinsic energy barrier to resist the rotational movements between the two subunits, giving the same degree of increase in the two rates. The mutation-induced increase in the maximal rate of the fast phase for the forward mRNA translocation results mainly from the increase in the rate of the ribosomal unlocking, a conformational change in the ribosome that widens the mRNA channel for the mRNA translocation to take place, which could be partly due to the effect of the mutation on the intrasubunit 30S head rotation. Moreover, we study the translation rate of the WT and mutant ribosomes. It is shown that the translation rate versus the concentration of EF-G-GTP does not follow the Michaelis-Menten (MM) kinetics, which is in sharp contrast to the general property of other enzymes that the rate of the enzymatic reaction versus the concentration of a substrate follows the MM kinetics. The physical origin of this non-MM kinetics for the ribosome is revealed.
资助信息	National Natural Science Foundation of China [11374352]
语种	英语
公开日期	2015-04-14
内容类型	期刊论文
源URL	[http://ir.iphy.ac.cn/handle/311004/59572]
专题	物理研究所_物理所公开发表论文_物理所公开发表论文_期刊论文
推荐引用方式 GB/T 7714	Xie, P. Biphasic character of ribosomal translocation and non-Michaelis-Menten kinetics of translation[J]. PHYSICAL REVIEW E,2014,90(6).
APA	Xie, P.(2014).Biphasic character of ribosomal translocation and non-Michaelis-Menten kinetics of translation.PHYSICAL REVIEW E,90(6).
MLA	Xie, P."Biphasic character of ribosomal translocation and non-Michaelis-Menten kinetics of translation".PHYSICAL REVIEW E 90.6(2014).