Identification of a Potential Membrane-Targeting Sequence in the C-Terminus of the F Plasmid Segregation Protein SopA

Mishra, D and Pahujani, S and Mitra, N and Srivastava, A and Srinivasan, R (2021) Identification of a Potential Membrane-Targeting Sequence in the C-Terminus of the F Plasmid Segregation Protein SopA. In: Journal of Membrane Biology . (In Press)

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Abstract

Abstract: Stable maintenance and partitioning of the �Fertility� plasmid or the F plasmid in its host Escherichia coli require the function of a ParA superfamily of proteins known as SopA. The mechanism by which SopA mediates plasmid segregation is well studied. SopA is a nucleoid-binding protein and binds DNA in an ATP-dependent but sequence non-specific manner. ATP hydrolysis stimulated by the binding of the SopBC complex mediates the release of SopA from the nucleoid. Cycles of ATP-binding and hydrolysis generate an ATPase gradient that moves the plasmid through a chemophoresis force. Nucleoid binding of SopA thus assumes a central role in its plasmid-partitioning function. However, earlier work also suggests that the F plasmid can be partitioned into anucleate cells, thus implicating nucleoid independent partitioning. Interestingly, SopA is also reported to be associated with the inner membrane of the bacteria. Here, we report the identification of a possible membrane-targeting sequence, a predicted amphipathic helix, at the C-terminus of SopA. Molecular dynamics simulations indicate that the predicted amphipathic helical motif of SopA has weak affinity for membranes. Moreover, we experimentally show that SopA can associate with bacterial membranes, is detectable in the membrane fractions of bacterial lysates, and is sensitive to the membrane potential. Further, unlike the wild-type SopA, a deletion of the C-terminal 29 amino acids results in the loss of F plasmids from bacterial cells. Graphic Abstract: Figure not available: see fulltext. © 2021, Springer Science+Business Media, LLC, part of Springer Nature.

Item Type:	Journal Article
Publication:	Journal of Membrane Biology
Publisher:	Springer
Additional Information:	copyright to this article belongs to Springer
Department/Centre:	Division of Biological Sciences > Molecular Biophysics Unit
Date Deposited:	03 Feb 2021 09:49
Last Modified:	03 Feb 2021 09:49
URI:	http://eprints.iisc.ac.in/id/eprint/67822

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