Chloroplast stromal processing peptidase activity is modulated by transit peptide determinants that include inhibitory roles for its N-terminal domain and initial Met
| Autor: | Mehea Park, Rong Zhong, Gayle K. Lamppa |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
0301 basic medicine
Chloroplasts Protein Conformation Biophysics Biochemistry Pisum 03 medical and health sciences Protein Domains Transit Peptide HSP70 Heat-Shock Proteins Amino Acid Sequence Binding site Plastid Molecular Biology Plant Proteins chemistry.chemical_classification biology Chemistry Peas Metalloendopeptidases Cell Biology biology.organism_classification Hsp70 Cell biology Amino acid Chloroplast Enzyme Activation 030104 developmental biology Cysteine Protein Binding |
| Zdroj: | Biochemical and biophysical research communications. 503(4) |
| ISSN: | 1090-2104 |
| Popis: | The stromal processing peptidase (SPP) removes transit peptides as precursor proteins enter the chloroplast and different plastid types. SPP is synthesized as a latent, inactive precursor (preSPP) with an atypically long transit peptide. Determinants in the pea (Pisum sativum) SPP transit peptide that regulate mature SPP activation were investigated. Mutational and chemical analyses with protein modifying agents (NEM and APMA) showed a conserved transit peptide Cys-X-Ser/Thr-Cys motif did not inhibit SPP via a "cysteine switch" mechanism through His-X-X-Glu-His site interactions, although cysteines in mature SPP contribute to an active conformation. Significantly, a transit peptide deletion of only the N-terminal 28 amino acids activates SPP located downstream. Short deletions within this region suggest removal of the initial Met plays a pivotal, mechanistic role. Other deletions of ∼30 amino acids along the length of the transit peptide do not individually trigger activity, but larger deletions including Met have an additive effect indicating its removal may be a critical early step during preSPP import. Interestingly, the active preSPP deletion mutants no longer possess predicted Hsp70 binding sites including initial Met, thus Hsp70 interactions may restrict SPP from attaining an active conformation. |
| Databáze: | OpenAIRE |
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