Htz1 protects euchromatic marks from encroaching heterochromatin.

Madhani/Elsevier

Avariant histone called H2A.Z (Htz1 in budding yeast) is an antisilencing protein, according to Marc Menenghini, Michelle Wu, and Hiten Madhani (University of California, San Francisco, CA). They propose that Htz1 protects the transcriptionally active euchromatic state from the threat of spreading heterochromatin.

When H2A.Z is added in vitro to replace H2A, the resulting nucleosomes are resistant to higher order condensation. But the in vivo significance of this result was unclear. Now, along comes the new array data. “We got this bizarre result,” says Madhani. “The genes that were repressed [after Htz1 loss] were clustered near telomeres.” Other repressed genes were huddled near the mating region, which is the other major silenced region in yeast chromatin.

The repression was partially reversed by deleting either the silencing protein Sir2 or a mating region silencing element. Repression after Htz1...

The Rockefeller University Press
2003
The Rockefeller University Press
2003
You do not currently have access to this content.