A role for the last C-terminal helix of the F plasmid segregating protein SopA in nucleoid binding and plasmid maintenance

• Published in: Plasmid 2022-01, Vol.119-120, p.102617-102617, Article 102617
• Main Authors: Mishra, Dipika, Jakhmola, Anirudh, Srinivasan, Ramanujam
• Format: Article
• Language: English
• Subjects: Bacterial Proteins - metabolism; DNA segregation; Escherichia coli - genetics; Escherichia coli - metabolism; Escherichia coli Proteins - genetics; Escherichia coli Proteins - metabolism; F Factor; F plasmid; ParA family; Plasmid maintenance; Plasmids - genetics; SopA
• ISSN: 0147-619X; 1095-9890
• DOI: 10.1016/j.plasmid.2022.102617

The rapid emergence and spread of antibiotic resistance is a growing global burden. Antibiotic resistance is often associated with large single or low copy number plasmids, which rely upon cytoskeletal proteins for their stable maintenance. While the mechanism of plasmid partitioning has been well established for the R plasmids, the molecular details by which the F plasmid is maintained is only beginning to emerge. The partitioning function of the F plasmid depends upon a ParA/ MinD family of proteins known as SopA. SopA, by virtue of its ATP-dependent non-specific DNA binding activity and association with the bacterial nucleoid, drives the segregation of the F plasmid into the daughter cells. This function further depends upon the stimulation of the ATPase activity of SopA by the SopBC complex. Here, we report that several residues in the last C-terminal helix in SopA play a crucial but distinct role in SopA function and plasmid maintenance. While the deletion of the last five residues in SopA does not affect its ability to bind the nucleoid or SopB, they severely affect the plasmid partitioning function. Further, we show that while mutations in certain polar residues in the C-terminal helix only mildly affect its localisation to the nucleoid, others cause defects in nsDNA binding and disrupt plasmid maintenance functions. •The last C-terminal tail of SopA is important for in its DNA binding and plasmid maintenance function.•A negatively charged residue E375 in the last C-terminal helix influences both ns-DNA binding and promoter binding of SopA•The last C-terminal helix thus plays an additional secondary but an important role in SopA function