Tissue- and expression level-specific chromatin looping at maize b1 epialleles

Plant Cell. 2009 Mar;21(3):832-42. doi: 10.1105/tpc.108.064329. Epub 2009 Mar 31.

Abstract

This work examines the involvement of chromatin looping in the transcriptional regulation of two epialleles of the maize (Zea mays) b1 gene, B-I and B'. These two epialleles are tissue-specifically regulated and are involved in paramutation. B-I and B' are expressed at high and low levels, respectively. A hepta-repeat approximately 100 kb upstream of the transcription start site (TSS) is required for both paramutation and high b1 expression. Using chromosome conformation capture, we show that the hepta-repeat physically interacts with the TSS region in a tissue- and expression level-specific manner. Multiple repeats are required to stabilize this interaction. High b1 expression is mediated by a multiloop structure; besides the hepta-repeat, other sequence regions physically interact with the TSS as well, and these interactions are epiallele- and expression level-specific. Formaldehyde-assisted isolation of regulatory elements uncovered multiple interacting regions as potentially regulatory.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alleles*
  • Chromatin / genetics
  • Chromatin / metabolism*
  • Gene Expression Regulation, Plant*
  • Nucleic Acid Conformation*
  • Tissue Distribution
  • Zea mays / anatomy & histology
  • Zea mays / genetics*

Substances

  • Chromatin