連細胞分裂都不公平了,天底下還有什麼公平的事?
Science Editors' Choice
Volume 320, Number 5877, Issue of 09 May 2008
BIOPHYSICS: Polar Preferences
In rod-shaped bacteria, proteins that mediate chemotaxis, cell division, and development are observed to localize to the poles. Recent evidence of heterogeneity in the composition of the bacterial cytoplasmic membrane and of the preferential binding of proteins to particular lipids suggests that membrane architecture may contribute to protein localization. For example, cardiolipin is involved in the polar and septal targeting of the Escherichia coli osmosensory transporter ProP. Cardiolipin is a phospholipid with high intrinsic curvature, and one proposal is that clusters of cardiolipin localize spontaneously to the poles, where the membrane is constrained by the curved cell wall. Mukhopadhyay et al. have extended their quantitative biophysical model to include the elastic energy of the membrane (which penalizes a deformation of the membrane away from the cell wall-imposed geometry), the interaction energy between lipids, and entropy. They show that variations in osmotic pressure, the force that pins the membrane to the cell wall, can regulate localization. The model predicts the minimum membrane fraction of cardiolipin required for domain formation and a polar localization that are consistent with the experimentally observed critical concentration of cardiolipin required for polar localization of ProP. -- VV Biophys. J. 94, 10.1529/biophysj.107.126920 (2008).
1 則留言:
有越來越多證據顯示,細菌分裂的時候,裏面裝的和鑲在表面上的,都不是均勻分布的。有人認為這是「細菌老化」的原因。
如果把細菌拿來猛烈地搖動,讓東西的分布更均勻,不知道細菌是不是就不會老化了?
狂想曲:每天晃來晃去的人會不會因此比較年輕啊?常常坐海盜船有沒有回春的效果呢?
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