This is a comic fantasy, not a detailed theoretical model :) grupos.unican.es/Motores_moleculares/research.htm Figure 1. Proposed evolution of membrane motor ATPases. Evolution of membrane-anchored DNA and protein translocases. Comparison of single-stranded DNA pumps, such as TrwB-like coupling proteins (a), double stranded DNA transporters of the FtsK/SpoIIIE protein family (b), protein/effector (purple) translocators like VirB4-like proteins(c) and F-type ATPases (d). RecA/AAA+ proteins are motor ATPases Associated to a large variety of cellular Activities (i.e. DNA unwinding, protein folding, DNA transport…). Interestingly, all members of this family share a striking structural similarity, which suggests they operate under a common mechanism and share a common evolutionary origin. Understanding how these hexameric motors emerged during evolution is a difficult task. It has been argued that the F-type ATPases emerged as a modular enzyme that was formed by the combination of a RNA or DNA helicase and a proton channel. An evolutionary scenario has been proposed in which their ancestors were membrane translocases that, initially coupled ATP hydrolysis to RNA/DNA translocation across the membrane and, subsequently, to protein translocation (Cabezon et al., 2012)(see figure 1). The evolution of an F-ATPase from the hypothetical protein translocase could have resulted from mutations that increased the hydrophobicity of the inner space of the ring, impeding protein translocation. With the transported protein trapped in the translocase, the torque generated by ATP hydrolysis would have caused the rotation of the entire central oligomer relative to the membrane channel (Mulkidjanian et al., 2007). See: https://youtube/watch?feature=player_embedded&v=9kP79bTd5aA https://bioslawek.files.wordpress/2013/10/dddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd.jpg?w=1232&h=854
Posted on: Fri, 09 Jan 2015 21:38:30 +0000
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