a new principle for information storage in an enzymatic pathway model信息存储在一个酶途径的新原理模型.pdfVIP

A New Principle for Information Storage in an Enzymatic Pathway Model 1* 2 1 ´ 1 Bruno Delord , Hugues Berry , Emmanuel Guigon , Stephane Genet ´ ´ ´ ´ 1 Institut National de la Sante et de la Recherche Medicale (INSERM), Unite 742, Universite Pierre et Marie Curie-Paris 6 (UPMC), Paris, France, 2 Institut National de Recherche ´ en Informatique et en Automatique (INRIA), Unite Futurs, Team Alchemy, Orsay, France Strong experimental evidence indicates that protein kinase and phosphatase (KP) cycles are critical to both the induction and maintenance of activity-dependent modifications in neurons. However, their contribution to information storage remains controversial, despite impressive modeling efforts. For instance, plasticity models based on KP cycles do not account for the maintenance of plastic modifications. Moreover, bistable KP cycle models that display memory fail to capture essential features of information storage: rapid onset, bidirectional control, graded amplitude, and finite lifetimes. Here, we show in a biophysical model that upstream activation of KP cycles, a ubiquitous mechanism, is sufficient to provide information storage with realistic induction and maintenance properties: plastic modifications are rapid, bidirectional, and graded, with finite lifetimes that are compatible with animal and human memory. The maintenance of plastic modifications relies on negligible reaction rates in basal conditions and thus depends on enzyme nonlinearity and activation properties of the activity-dependent KP cycle. Moreover, we show that information coding and memory maintenance are robust to stochastic fluctuations inherent to