Question

What recent evidence has suggested that peroxisomes did not arise via endosymbiosis?

Answer 1

The hypothesized process by which prokaryotes gave rise to the first eukaryotic cells is known as endosymbiosis.

Peroxisomes are membrane-bound organelles in most eukaryotic cells, primarily involved in lipid metabolism and the conversion of reactive oxygen species such as hydrogen peroxide into safer molecules like water and oxygen.

The ability of peroxisomes to divide and import proteins post-translationally, just like mitochondria and chloroplasts, supports an endosymbiotic origin. However, this view has been challenged by recent discoveries that mutant, peroxisome-less cells restore peroxisomes upon introduction of the wild-type gene, and that peroxisomes are formed from the Endoplasmic Reticulum. The lack of a peroxisomal genome precludes the use of classical analyses, as those performed with mitochondria or chloroplasts, to settle the debate.

Altogether recent researches indicate that the peroxisome does not have an endosymbiotic origin and that its proteins were recruited from pools existing within the primitive eukaryote. Moreover the reconstruction of primitive peroxisomal proteomes suggests that ontogenetically as well as phylogenetically, peroxisomes stem from the Endoplasmic Reticulum.