SINGLE-MOLECULE STUDIES ON DNA COMPACTION & GENE REGULATION IN BACTERIA CELLS

Abstract

The understanding of how bacteria perform their chromosomal DNA packaging and gene regulation has direct implications to understanding bacterial pathogenesis and this requires immediate attention given the recent emergence of deadly antibiotics resistance bacteria strains. One of the key mediating factors in bacterial chromosomal DNA compaction and gene regulation is the bacterial nucleoid-associated proteins (NAPs). How these bacteria nucleoid-associated proteins mediate their biological functions are not clear and have proven elusive. The answer may be in the NAPs DNA architectural properties, which is the alteration of DNA topology upon DNA-binding. By using highly sensitive single-molecule techniques, we showed that the rigid nucleoprotein filaments formed by NAPs is a conserved DNA-protein structure important for bacterial NAPs gene silencing functions. We further showed that the nucleoid-associated proteins are able to use their distinct DNA-binding mode(s) to regulate DNA supercoiling. These findings provide a mechanistic and novel platform for microbiologists to understand how NAPs may perform their chromosomal DNA organization and gene regulatory functions in vivo.