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A cytoplasm-specific activity encoded by the Trithorax-like ATX1 gene
Ivan Ndamukong1, Hanna Lapko, Ronald L Cerny
1School of Biological Sciences, University of Nebraska, Lincoln, Nebraska, USA.
Nucleic Acids Research
|January 20, 2011
Summary
A novel protein isoform, soloSET, derived from the ATX1 gene locus in Arabidopsis, functions in the cytoplasm. This isoform regulates the elongation factor 1A (EF1A) and impacts cytoskeletal actin bundling, distinct from its nuclear histone-modifying role.
Area of Science:
- Molecular Biology
- Cell Biology
- Plant Science
Background:
- Eukaryotes generate proteome complexity through mechanisms like alternative splicing and promoter usage.
- Trithorax proteins, such as Arabidopsis ATX1, are known histone modifiers involved in gene regulation.
- The ATX1 locus in Arabidopsis encodes multiple protein products, suggesting diverse cellular functions.
Purpose of the Study:
- To investigate a novel isoform encoded by the ATX1 locus.
- To determine the cellular localization and function of this new isoform.
- To elucidate the distinct roles of ATX1 isoforms in Arabidopsis.
Main Methods:
- Analysis of gene expression and protein localization.
- Biochemical assays to identify protein substrates.
- Phenotypic analysis of mutant lines lacking specific isoforms.
Main Results:
- A novel ATX1 isoform, soloSET, containing only the SET domain, is produced from an internal promoter.
- soloSET is localized exclusively in the cytoplasm and targets elongation factor 1A (EF1A).
- Loss of soloSET function, but not the nuclear ATX1-SET activity, affects cytoskeletal actin bundling.
Conclusions:
- The ATX1 locus produces functionally distinct isoforms with non-redundant roles.
- soloSET represents a novel cytoplasmic Trithorax family member with a role independent of chromatin modification.
- These findings expand our understanding of proteome complexity and cellular regulation in Arabidopsis.
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