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Developmentally regulated late mRNAs in the encystment of Physarum polycephalum plasmodia
L Savard1, A Laroche, G Lemieux
1Département de biologie, Faculté des Sciences, Université Laval, Québec, Canada.
Abstract:
Physarum polycephalum plasmodia survive adverse conditions by transforming into encysted cells called spherules. In this work we analysed the developmentally regulated mRNAs from the late stages of spherulation. A cDNA library was constructed and four abundant mRNAs were identified. One of the mRNAs was present in trace amounts in early spherules, while the other three were found only in late spherules. A cDNA clone for one of the late spherulation specific mRNAs was sequenced. It codes for a 332-amino-acid protein that did not show significant similarities with any known protein. Since the mRNA for this protein accumulates during spherulation, the protein was called spherulin 4. This protein has many features of a plasma membrane protein; it contains a signal peptide and a long hydrophobic region, which could serve as a transmembrane anchor. Another interesting feature is the presence of seven consecutive glycine residues in the N-terminal region. This is even more remarkable since the protein is not rich in glycine.
Insights
Physarum polycephalum transforms into spherules under stress. Researchers identified a novel protein, spherulin 4, specific to late-stage spherulation, potentially involved in plasma membrane function.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Physarum polycephalum plasmodia form resistant spherules during adverse conditions.
- Understanding the molecular mechanisms of spherulation is crucial for studying cellular resilience.
Purpose of the Study:
- To identify and characterize developmentally regulated mRNAs during the late stages of Physarum polycephalum spherulation.
- To investigate novel proteins involved in the encystment process.
Main Methods:
- Construction of a cDNA library from late-stage spherules.
- Differential screening and sequencing of abundant, developmentally regulated mRNAs.
- Bioinformatic analysis of the identified protein sequence.
Main Results:
- Four abundant mRNAs were identified, with three specific to late-stage spherulation.
- A novel 332-amino-acid protein, named spherulin 4, was characterized.
- Spherulin 4 exhibits features of a plasma membrane protein, including a signal peptide and a transmembrane anchor region.
- A unique feature of spherulin 4 is a consecutive glycine-rich region in its N-terminus.
Conclusions:
- Spherulin 4 is a novel protein specifically expressed during the late stages of Physarum polycephalum spherulation.
- The protein's predicted structure suggests a role in plasma membrane function during encystment.
- Further research is warranted to elucidate the precise function of spherulin 4 in cellular resilience.