Originally published as Genetics Published Articles Ahead of Print on March 16, 2009.

Genetics, Vol. 182, 145-159, May 2009, Copyright © 2009
doi:10.1534/genetics.109.101386

The Multi-AT-Hook Chromosomal Protein of Drosophila melanogaster, D1, Is Dispensable for Viability

Karen S. Weiler*,{dagger},1 and Suman Chatterjee*

* Department of Biology, West Virginia University, Morgantown, West Virginia 26506 and {dagger} Department of Biological Sciences, Idaho State University, Pocatello, Idaho 83209

1 Address for correspondence: Department of Biology, 53 Campus Dr., West Virginia University, Morgantown, WV 26506-6057.
E-mail: karen.weiler{at}mail.wvu.edu

The D1 protein is a high mobility group A (HMGA)-like nonhistone chromosomal protein with primary localization to certain AT-rich satellite DNA sequences within heterochromatin. The binding of D1 to euchromatic sequences is less studied and the functional significance of its chromosomal associations is unclear. By taking advantage of existing P-insertion alleles of the D1 gene, I generated D1 null mutations to investigate the phenotypic effect of loss of the D1 gene. In contrast to a previous report, I determined that the D1 gene is not essential for viability of Drosophila melanogaster, and moreover, that loss of D1 has no obvious phenotypic effects. My tests for an effect of D1 mutations on PEV revealed that it is not a suppressor of variegation, as concluded by other investigators. In fact, the consequence of loss of D1 on one of six variegating rearrangements tested, T(2;3)SbV, was dominant enhancement of PEV, suggesting a role for the protein in euchromatic chromatin structure and/or transcription. A study of D1 protein sequence conservation highlighted features shared with mammalian HMGA proteins, which function as architectural transcription factors.