The T4 Phage DNA Mimic Protein Arn Inhibits the DNA Binding Activity of the Bacterial Histone-like Protein H-NS

Abstract

Background: DNA mimic proteins prevent DNA-binding proteins from binding to DNA. Results: T4 phage DNA mimic protein Arn disrupts H-NS⅐DNA binding and neutralizes the gene-silencing effect of H-NS. Conclusion: Arn participates in viral anti-host defense system by its DNA mimicking properties. Significance: This anti-H-NS function of Arn represents a novel battle mechanism between phage and bacteria.

H-NS and RNA polymerase: a love–hate relationship?

“…For example, 'invasive' DNA can encode proteins that counteract the repressive effects of H-NS. Such H-NS inhibitors are known to be encoded in several bacteriophage genomes [51,52]. Furthermore, host-encoded proteins frequently interfere in the relationship between RNA polymerase and H-NS.…”

New paradigm of functional regulation by DNA mimic proteins: Recent updates

“…In the same report, Arn was further shown to have the additional ability of interacting with the bacterial histone‐like protein H‐NS . Electron microscopy clearly showed that the addition of Arn disrupted the higher‐order structure of plasmid DNA that was induced by H‐NS . H‐NS is a global gene silencer that also functions as a bacterial defense protein by forming a higher‐order structure made up of H‐NS and foreign DNA .…”

“…In 2005, Putnam and Tainer suggested that Arn might fulfill this role by acting as a DMP because it contains a similar pattern of negatively charged amino acids to two other determined DMPs, Ocr and DinI (2). In 2014, Ho et al reported the crystal structure of Arn and concluded that this protein is indeed a DMP because it contains a B-form DNA-like charge and shape (28). In the same report, Arn was further shown to have the additional ability of interacting with the bacterial histone-like protein H-NS (28).…”

“…In 2014, Ho et al reported the crystal structure of Arn and concluded that this protein is indeed a DMP because it contains a B-form DNA-like charge and shape (28). In the same report, Arn was further shown to have the additional ability of interacting with the bacterial histone-like protein H-NS (28). Electron microscopy clearly showed that the addition of Arn disrupted the higher-order structure of plasmid DNA that was induced by H-NS (28).…”

“…In this case, the real biological targets of these four DMPs could be other DNA-binding proteins. Thus even when the interactions between bacterial histone-like proteins and DMPs can be confirmed by different in vitro methods (20,21,23,24,28), it is still necessary to identify the biological meanings of these interactions in vivo.…”