The Highly Similar Arabidopsis Homologs of Trithorax ATX1 and ATX2 Encode Proteins with Divergent Biochemical Functions

Authors

Abdelaty Saleh, University of Nebraska-Lincoln
Raul Alvarez-Venegas, University of Nebraska-Lincoln
Mehtap Yilmaz, University of Nebraska-Lincoln
Oahn-Le, University of Nebraska-Lincoln
Guichuan Hou, University of Nebraska - Lincoln
Monther Sadder, University of Nebraska - Lincoln
Ayed Al-Abdallat, University of Nebraska-Lincoln
Yuannan Xia, University of Nebraska - LincolnFollow
Guoqinq Lu, University of Nebraska-Omaha
Istvan Ladunga, University of Nebraska at LincolnFollow
Zoya Avramova, University of Nebraska-LincolnFollow

ORCID IDs

Istvan Ladunga

Document Type

Article

Date of this Version

2008

Citation

The Plant Cell, Vol. 20: 568–579, March 2008

Comments

Copyright 2008 American Society of Plant Biologists

Abstract

Gene duplication followed by functional specialization is a potent force in the evolution of biological diversity. A comparative study of two highly conserved duplicated genes, ARABIDOPSIS TRITHORAX-LIKE PROTEIN1 (ATX1) and ATX2, revealed features of both partial redundancy and of functional divergence. Although structurally similar, their regulatory sequences have diverged, resulting in distinct temporal and spatial patterns of expression of the ATX1 and ATX2 genes. We found that ATX2 methylates only a limited fraction of nucleosomes and that ATX1 and ATX2 influence the expression of largely nonoverlapping gene sets. Even when coregulating shared targets, ATX1 and ATX2 may employ different mechanisms. Most remarkable is the divergence of their biochemical activities: both proteins methylate K4 of histone H3, but while ATX1 trimethylates it, ATX2 dimethylates it. ATX2 and ATX1 provide an example of separated K4 di from K4 trimethyltransferase activity.