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

• Similarities in the DNA binding properties of H-NS and RNA polymerase.
• Interactions between H-NS and RNA polymerase throughout the transcription cycle.
• H-NS-like proteins in diverse species of bacteria.
• Mechanisms by which H-NS repression can be alleviated.

Histone-like nucleoid structuring (H-NS) protein is a component of bacterial chromatin and influences gene expression both locally and on a global scale. Although H-NS is broadly considered a silencer of transcription, the mechanisms by which H-NS inhibits gene expression remain poorly understood. Here we discuss recent advances in the context of a ‘love–hate’ relationship between H-NS and RNA polymerase, in which these factors recognise similar DNA sequences but interfere with each other's activity. Understanding the complex relationship between H-NS and RNA polymerase may unite the multiple models that have been proposed to describe gene silencing by H-NS.