Identification and molecular analysis of interaction sites in the MtSEO-F1 protein involved in forisome assembly

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Date
2020
Volume
144
Issue
Journal
International Journal of Biological Macromolecules
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Book Title
Publisher
New York, NY [u.a.] : Elsevier
Abstract

Forisomes are large mechanoprotein complexes found solely in legumes such as Medicago truncatula. They comprise several “sieve element occlusion by forisome” (SEO-F) subunits, with MtSEO-F1 as the major structure-forming component. SEO-F proteins possess three conserved domains –an N-terminal domain (SEO-NTD), a potential thioredoxin fold, and a C-terminal domain (SEO-CTD)– but structural and biochemical data are scarce and little is known about the contribution of these domains to forisome assembly. To identify key amino acids involved in MtSEO-F1 dimerization and complex formation, we investigated protein-protein interactions by bimolecular fluorescence complementation and the analysis of yeast two-hybrid and random mutagenesis libraries. We identified a SEO-NTD core region as the major dimerization site, with abundant hydrophobic residues and rare charged residues suggesting dimerization is driven by the hydrophobic effect. We also found that ~45% of the full-length MtSEO-F1 sequence must be conserved for higher-order protein assembly, indicating that large interaction surfaces facilitate stable interactions, contributing to the high resilience of forisome bodies. Interestingly, the removal of 62 amino acids from the C-terminus did not disrupt forisome assembly. This is the first study unraveling interaction sites and mechanisms within the MtSEO-F1 protein at the level of dimerization and complex formation. © 2018

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Rose, J., Visser, F., Müller, B., Senft, M., Groscurth, S., Sicking, K. F., et al. (2020). Identification and molecular analysis of interaction sites in the MtSEO-F1 protein involved in forisome assembly (New York, NY [u.a.] : Elsevier). New York, NY [u.a.] : Elsevier. https://doi.org//10.1016/j.ijbiomac.2019.12.092
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CC BY-NC-ND 4.0 Unported