Nucleosome core particles in eukaryotes are linked by a stretch of DNA that is 
usually associated with a linker histone. Here, we show in yeast, that the 
presence of yeast linker histone Hho1p represses expression of a pol II 
transcribed gene (MET15) embedded in the rDNA. In vivo deletions of Hho1p 
sequences showed that the second globular domain is sufficient for that 
repression, whereas the presence of the N terminus is required for its 
derepression. In contrast, a run-on assay confirmed by a ChIP experiment showed 
that Hho1p is required for maximal pol I processivity during rDNA transcription. 
Psoralen accessibility experiments indicated that Hho1p is necessary for normal 
rDNA compaction. DNA array expression analysis comparing RNA transcripts in 
wild-type and hho1 strains before and after a heat-shock showed that Hho1p is 
necessary to achieve wild-type mRNA levels of transcripts that encode ribosomal 
components. Taken together, our results suggest that Hho1p is involved in rDNA 
compaction, and like core histones, is required for efficient rDNA transcription 
by pol I.