"The conservation of Pex11 function across plants and yeast may indicate a similar role in human cells."
A Protein That Makes Peroxisomes Grow and Shrink
A study published in Nature Communications by researchers at Rice University has identified the PEX11 protein as a regulator of size changes in peroxisomes during the seed-to-seedling stage in Arabidopsis thaliana plants.
Background
Peroxisomes are membrane-bound cellular compartments that break down stored fatty acids for energy in plant cells before photosynthesis begins. During the transition from seed to seedling, these organelles enlarge to process fatty acids, then shrink to normal size once photosynthesis starts.
Key Findings
The research team, led by Bonnie Bartel and Nathan Tharp, investigated the role of PEX11, a protein previously known to assist with peroxisome division. The study found that PEX11 also regulates the expansion and contraction of peroxisomes during early development.
Using CRISPR technology, researchers disabled combinations of the five genes that encode PEX11 in Arabidopsis. Removing all five genes was lethal. However, plants with specific gene combinations survived, exhibiting abnormal peroxisome behavior:
- Peroxisomes grew excessively large, with some extending the entire length of the cell.
- The organelles did not shrink back to normal size after the seedling stage.
- Mutants lacked or had significantly reduced internal membrane vesicles that normally form during fatty acid processing.
Evolutionary Conservation
Researcher Nathan Tharp introduced the yeast version of the Pex11 protein into the mutant plant cells. This restored normal peroxisome size and vesicle formation, suggesting the protein's function is conserved across species separated by over a billion years of evolution.
Implications
According to the researchers, the conservation of Pex11 function across plants and yeast may indicate a similar role in human cells. Peroxisomes are involved in certain human diseases and are used in bioengineering applications, suggesting the findings could have relevance for medical research and biotechnology.