Single-molecule Studies on the Role of Nucleoid-associated Proteins in Bacterial Chromatin

Abstract

Bacterial chromatin contains the genetic code of bacteria, assembled by many factors into a compact structure called nucleoid. Single-molecule manipulation by magnetic tweezers and single-molecule imaging by atomic force microscopy are performed to gain insight into the molecular mechanism of nucleoid-associated proteins in shaping the bacterial nucleoid and regulating the gene expression. We investigate the role of gene silencing protein MvaT and MvaU in Pseudomonas aeruginosa, an important pathogens that can cause chronic infections, showing for the first time the direct evidence on the importance of nucleoprotein filaments formation for achieving gene silencing function in vivo. In addition, to better understand the process of gene anti-silencing, the DNA binding properties of Ler from pathogenic Escherichia coli and its competition with H-NS nucleoprotein filaments are studied. The works done in this thesis will provide insight and extend our understanding on the role of nucleoid-associated proteins in bacterial chromatin.