this page is secure
Extreme variation in rates of evolution in the plastid Clp protease complex
Eukaryotic cells represent an intricate collaboration between multiple genomes, even down to the level of multi‐subunit complexes in mitochondria and plastids. One such complex in plants is the caseinolytic protease (Clp), which plays an essential role in plastid protein turnover.
The proteolytic core of Clp comprises subunits from one plastid‐encoded gene (
clpP1
) and multiple nuclear genes. The
clpP1
gene is highly conserved across most green plants, but it is by far the fastest evolving plastid‐encoded gene in
some angiosperms. To better understand these extreme and mysterious patterns of divergence, we investigated the history of
clpP1
molecular evolution across green plants by extracting sequences from 988 published plastid genomes. We find that
clpP1
has
undergone remarkably frequent bouts of accelerated sequence evolution and architectural changes (e.g. a loss of introns and
RNA
‐editing sites) within seed plants. Although
clpP1
is often assumed to be a pseudogene in such cases, multiple lines of evidence
suggest that this is rarely true. We applied comparative native gel electrophoresis of chloroplast protein complexes followed by protein mass spectrometry in two species within the angiosperm genus
Silene
, which has highly elevated and heterogeneous rates of
clpP1
evolution. We confirmed that
clpP1
is expressed as a stable protein and forms oligomeric complexes with the nuclear‐encoded Clp subunits, even in one of the most divergent
Silene
species. Additionally, there is a tight correlation between amino
acid substitution rates in
clpP1
and the nuclear‐encoded Clp subunits across a broad sampling of angiosperms, suggesting continuing selection on interactions within this complex.
No References
No Citations
No Supplementary Data
No Article Media
No Metrics
Keywords: Clp complex; caseinolytic protease; chloroplast; evolution; evolutionary rates
Document Type: Research Article
Publication date: April 1, 2019
Receive new issue alert