A Repulsive Electrostatic Mechanism for Protein Export through the Type III Secretion Apparatus
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Issue Date
2010-02Author
Rathinavelan, Thenmalarchelvi
Zhang, Lingling
Picking, Wendy Lynn
Weis, David D.
De Guzman, Roberto N.
Im, Wonpil
Publisher
Elsevier
Type
Article
Article Version
Scholarly/refereed, publisher version
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Show full item recordAbstract
Many Gram-negative bacteria initiate infections by injecting effector proteins into host cells through the type III secretion apparatus, which is comprised of a basal body, a needle, and a tip. The needle channel is formed by the assembly of a single needle protein. To explore the export mechanisms of MxiH needle protein through the needle of Shigella flexneri, an essential step during needle assembly, we have performed steered molecular dynamics simulations in implicit solvent. The trajectories reveal a screwlike rotation motion during the export of nativelike helix-turn-helix conformations. Interestingly, the channel interior with excessive electronegative potential creates an energy barrier for MxiH to enter the channel, whereas the same may facilitate the ejection of the effectors into host cells. Structurally known basal regions and ATPase underneath the basal region also have electronegative interiors. Effector proteins also have considerable electronegative potential patches on their surfaces. From these observations, we propose a repulsive electrostatic mechanism for protein translocation through the type III secretion apparatus. Based on this mechanism, the ATPase activity and/or proton motive force could be used to energize the protein translocation through these nanomachines. A similar mechanism may be applicable to macromolecular channels in other secretion systems or viruses through which proteins or nucleic acids are transported.
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This is the publisher's version. Copyright 2009 by Elsevier.
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Citation
Rathinavelan, Thenmalarchelvi, Lingling Zhang, Wendy L. Picking, David D. Weis, Roberto N. De Guzman, and Wonpil Im. "A Repulsive Electrostatic Mechanism for Protein Export through the Type III Secretion Apparatus." Biophysical Journal 98.3 (2010): 452-61. http://dx.doi.org/10.1016/j.bpj.2009.10.030.
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