Electrostatic strain and concerted motions in the transient complex between plastocyanin and cytochrome f from the cyanobacterium Phormidium laminosum

10 páginas, 9 figuras, 1 tablaMany fleeting macromolecular interactions, like those being involved in electron transport, are essential in biology. However, little is known about the behaviour of the partners and their dynamics within their short-lived complex. To tackle such issue, we have performed molecular dynamics simulations on an electron transfer complex formed by plastocyanin and cytochrome f from the cyanobacterium Phormidium laminosum. Besides simulations of the isolated partners, two independent trajectories of the complex were calculated, starting from the two different conformations in the NMR ensemble. The first one leads to a more stable ensemble with a shorter distance between the metal sites of the two partners. The second experiences a significant drift of the complex conformation. Analyses of the distinct calculations show that the conformation of cytochrome f is strained upon binding of its partner, and relaxes upon its release. Interestingly, the principal component analysis of the trajectories indicates that plastocyanin displays a concerted motion with the small domain of cytochrome f that can be attributed to electrostatic interactions between the two proteins.This work was supported in part by research grants from the Spanish Ministry of Science and Innovation (BFU2006-01361) and the Andalusian Government (BIO-198 and P06-CVI-01713). FJML is the recipient of a FPI fellowship (BES-2005-10404) from the Spanish Ministry of Science and Innovation.Peer reviewe