Abstract
Metacaspases are a group of cysteine proteases found in plants, protozoa and fungi, which share structural similarities and are considered functional homologs of metazoan caspases. Although metacaspases were discovered almost two decades ago, research on their characteristics, functions and mechanisms remain rather limited. In order to get a better understanding of plant metacaspases, I conducted several studies on metacaspases from the model plant Arabidopsis thaliana. My first project presented in Chapter Two is domain functional analysis of AtMC4 and AtMC9, two type II Arabidopsis metacaspases (AtMCs) that are distinct in many of their biochemical characteristics. Through domain swapping, I generated six chimeric type II MCs (called Domain Swap Proteins or DSPs) for all possible permutations of functional domains of AtMC4 and AtMC9. Subsequent activity assays and immunoblots of these DSPs (DSP1-DSP6) identified essential domain elements involved in each specific biochemical trait of either AtMC4 or AtMC9. Also, conserved "signature" residues in each domain of both AtMC4 and AtMC9 were identified, which relates to the origins of those metacaspases and eventually links AtMC9-like proteases with the evolution of more complex root archetypes in terrestrial plants. My second project presented in Chapter Three is about the in planta function of AtMC3. AtMC3 is an atypical member of the type I Arabidopsis metacaspases gene family. Research record on this metacaspases gene is close to none, which could be due to lack of proper knockout mutants. Utilizing the newly developed CRISPR/Cas9 technology, I created atmc3 knockout mutants. atmc3 mutant alone or in combination with other type I atmc mutants do not produce any visible abnormal phenotypes. However, when crossed into lsd1-related mutant background, atmc3 mutant displays an alleviating effect on the runaway cell death phenotype of lsd1, indicating that AtMC3 may act as a positive regulator in the HR cell death pathway. My third project presented in Chapter Four is about characterization of the underlying biochemical properties of type I AtMCs in vitro, for which no relevant research result are available so far. I expressed all three type I AtMC recombinant proteins in E.coli and tested their activation pH optima, calcium dependency as well as the potential effect of prodomains on those proteases’ activity levels. I also examined the significance of the conserved cysteines in those type I AtMCs through point mutations and found that most of those cysteines do not play a catalytic role in those AtMCs, although a slight exception was seen with AtMC1. My study provided the first available data set for biochemical characterization of Arabidopsis type I metacaspases.
Abstract from the paper’s OpenAlex record, shown for indexing and research. Copyright remains with the authors or the publisher.
The text the model read, with the source record’s inline markup (italics, sub- and superscripts) rendered and its character entities decoded; quote offsets refer to the raw text.
Claims 8
Claim · model-written summary
Domain swapping identified essential elements for biochemical traits of AtMC4 and AtMC9.
- Taxon
- Arabidopsis
Arabidopsist0 - Gene
- AtMC4 or AtMC9e0
- Outcome
- essential domain elements involved in each specific biochemical traite0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Subsequent activity assays and immunoblots of these DSPs (DSP1-DSP6) identified essential domain elements involved in each specific biochemical trait of either AtMC4 or AtMC9.”
t0“Arabidopsis metacaspases”
Claim · model-written summary
Conserved signature residues were identified in AtMC4 and AtMC9 domains.
- Taxon
- ArabidopsisArabidopsist0
- Gene
- AtMC4 and AtMC9e0
- Outcome
- conserved "signature" residuese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“conserved "signature" residues in each domain of both AtMC4 and AtMC9 were identified”
t0“Arabidopsis metacaspases”
Claim · model-written summary
AtMC9-like proteases were linked to evolution of more complex root archetypes.
- Taxon
- terrestrial plantse0
- Gene
- AtMC9-like proteasese0
- Outcome
- evolution of more complex root archetypese0
Not reportedDirection
Verbatim
e0“links AtMC9-like proteases with the evolution of more complex root archetypes in terrestrial plants.”
Claim · model-written summary
atmc3 knockout mutants showed no visible abnormal phenotype alone or with other type I atmc mutants.
- Taxon
- ArabidopsisArabidopsist0
- Material
- atmc3 mutante0
- Outcome
- do not produce any visible abnormal phenotypese0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“atmc3 mutant alone or in combination with other type I atmc mutants do not produce any visible abnormal phenotypes.”
t0“Arabidopsis metacaspases”
Claim · model-written summary
atmc3 alleviated the lsd1 runaway cell death phenotype when crossed into that background.
- Taxon
- ArabidopsisArabidopsist0
- Material
- atmc3 mutante0
- Treatment
- crossed into lsd1-related mutant backgrounde0
- Outcome
- runaway cell death phenotype of lsd1e0
- Direction
- alleviatinge0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“when crossed into lsd1-related mutant background, atmc3 mutant displays an alleviating effect on the runaway cell death phenotype of lsd1”
t0“Arabidopsis metacaspases”
Claim · model-written summary
AtMC3 may positively regulate HR cell death.
- Taxon
- ArabidopsisArabidopsist0
- Gene
- AtMC3e0
- Outcome
- HR cell death pathwaye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“AtMC3 may act as a positive regulator in the HR cell death pathway.”
t0“Arabidopsis metacaspases”
Claim · model-written summary
Most conserved cysteines in type I AtMCs were not catalytic, with a slight exception for AtMC1.
- Taxon
- ArabidopsisArabidopsist0
- Gene
- AtMCse0
- Outcome
- do not play a catalytic rolee0
- Qualifier
- slight exception was seen with AtMC1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“most of those cysteines do not play a catalytic role in those AtMCs, although a slight exception was seen with AtMC1.”
t0“Arabidopsis metacaspases”
Claim · model-written summary
The study provided the first biochemical characterization dataset for Arabidopsis type I metacaspases.
- Taxon
- ArabidopsisArabidopsise0
- Outcome
- data set for biochemical characterization of Arabidopsis type I metacaspasese0
Not reportedComparatorValue
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“My study provided the first available data set for biochemical characterization of Arabidopsis type I metacaspases.”
The same questions in other papers
loss of function · cytology · ArabidopsisPositive and negative results
6 papers in the same direction as this paper · 41 in the opposite direction
- no effect
- negative
- no effect
44 papers more in this group
See all 48 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.