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CSP41, a sequence-specific chloroplast mRNA binding protein, is an endoribonuclease
J Yang1, G Schuster, D B Stern
1Boyce Thompson Institute for Plant Research, Cornell University, Ithaca, New York 14853, USA.
The Plant Cell
|August 1, 1996
Summary
Chloroplast messenger RNA (mRNA) processing requires specific structures. This study identifies CSP41 protein as crucial for binding these structures and potentially regulating RNA processing or degradation in spinach.
Area of Science:
- Molecular Biology
- Plant Biochemistry
- RNA Processing
Background:
- Correct 3' processing of chloroplast precursor mRNAs (pre-mRNAs) is essential and depends on a 3' untranslated region stem-loop structure.
- In spinach, a stable complex forms between petD pre-mRNA and chloroplast proteins, including CSP29, CSP41, and CSP55.
Purpose of the Study:
- To purify and characterize Chloroplast Stem-Loop Binding Protein 41 (CSP41).
- To investigate the role of CSP41 in the 3' processing of petD pre-mRNA.
- To elucidate the interaction of CSP41 with other proteins and RNA elements.
Main Methods:
- Purification of CSP41 protein.
- Cloning and characterization of the csp41 gene.
- Bacterial expression and in vitro binding assays of CSP41.
- Assessing endoribonuclease activity of CSP41.
Main Results:
- CSP41 is encoded by a single nuclear gene.
- Bacterially expressed CSP41 specifically binds to the 3' stem-loop and AU-rich elements of petD pre-mRNA.
- CSP41 binding affinity is increased by association with CSP55.
- CSP41 exhibits significant nonspecific endoribonuclease activity.
Conclusions:
- CSP41 is likely involved in the 3' processing of petD pre-mRNA and/or RNA degradation.
- Differential regulation of RNA binding and ribonuclease activities under varying conditions suggests a potential in vivo regulatory mechanism.
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