Document Type
Article
Publication Date
7-1-2021
Abstract
Alx1, a homeodomain-containing transcription factor, is a highly conserved regulator of skeletogenesis in echinoderms. In sea urchins, Alx1 plays a central role in the differentiation of embryonic primary mesenchyme cells (PMCs) and positively regulates the transcription of most biomineralization genes expressed by these cells. The alx1 gene arose via duplication and acquired a skeletogenic function distinct from its paralog (alx4) through the exonization of a 41-amino acid motif (the D2 domain). Alx1 and Alx4 contain glutamine-50 paired-type homeodomains, which interact preferentially with palindromic binding sites in vitro. Chromatin immunoprecipitation sequencing (ChIP-seq) studies have shown, however, that Alx1 binds both to palindromic and half sites in vivo. To address this apparent discrepancy and explore the function of the D2 domain, we used an endogenous cis-regulatory module associated with Sp-mtmmpb, a gene that encodes a PMC-specific metalloprotease, to analyze the DNA-binding properties of Alx1. We find that Alx1 forms dimeric complexes on TAAT-containing half sites by a mechanism distinct from the well-known mechanism of dimerization on palindromic sites. We used transgenic reporter assays to analyze the functional roles of half sites in vivo and demonstrate that two sites with partially redundant functions are essential for the PMC-specific activity of the Sp-mtmmpb cis-regulatory module. Finally, we show that the D2 domain influences the DNA-binding properties of Alx1 in vitro, suggesting that the exonization of this motif may have facilitated the acquisition of new transcriptional targets and consequently a novel developmental function.
Recommended Citation
Guerrero-Santoro, Jennifer; Khor, Jian Ming; Açıkbaş, Ayşe Haruka; Jaynes, James B.; and Ettensohn, Charles A, "Analysis of the DNA-binding properties of Alx1, an evolutionarily conserved regulator of skeletogenesis in echinoderms" (2021). Department of Biochemistry and Molecular Biology Faculty Papers. Paper 194.
https://jdc.jefferson.edu/bmpfp/194
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.
PubMed ID
34157281
Language
English
Comments
This article is the author’s final published version in The Journal of biological chemistry, Volume 297, Issue 1, July 2021, Page 100901.
The published version is available at https://doi.org/10.1016/j.jbc.2021.100901. Copyright © Guerrero-Santoro et al.