An abundant chromosomal protein that seems to be involved in both genome architecture and transcription repression. Incubation with DNA in vitro gives fibrous structures 14.2 +/- 2.1 nm in thickness (naked DNA is 1.83 +/- 0.37 nm); does not significantly compact DNA. Binds to both coding and non-coding regions; binding within gene promoters correlates with decreased transcript levels, while binding within coding regions does not. Slight growth delay compared to wild-type. No fibrous chromosomal DNA isolated from cells, DNA condensation is normal. Chromatin DNA is more sensitive to micrococcal nuclease. Alters gene expression levels of about 10% of the genome. Belongs to the transcriptional regulator TrmB family.