Crystal Structural Analysis of <i>Oryza sativa</i> SGT1-TPR Domain

Crystal Structural Analysis of <i>Oryza sativa</i> SGT1-TPR Domain

SGT1 (the suppressor of the G2 allele of Skp1) functions as an adaptor protein that positively regulates plant defense and developmental processes. It comprises three functional domains: the tetratricopeptide repeat (TPR) domain, Chord SGT1 motif (CS), and SGT1-specific motif (SGS). In this study, w...

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Bibliographic Details
Main Authors: Yongqi Chang, Lifeng Ji, Yiling Qin, Yaqi Yi, Chen Qian, Jie Jiang, Tian Liu, Junfeng Liu, Xin Zhang
Format: Article
Language:English
Published: MDPI AG 2025-06-01
Series:Crystals
Subjects:
SGT1
TPR domain
crystal structure
<i>Oryza sativa</i>
Online Access:https://www.mdpi.com/2073-4352/15/6/543
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Summary:SGT1 (the suppressor of the G2 allele of Skp1) functions as an adaptor protein that positively regulates plant defense and developmental processes. It comprises three functional domains: the tetratricopeptide repeat (TPR) domain, Chord SGT1 motif (CS), and SGT1-specific motif (SGS). In this study, we resolved the crystal structure of the <i>Oryza sativa</i> OsSGT1-TPR domain at 1.53 Å resolution. Structural analysis showed that the TPR domain adopts a homo-dimeric architecture stabilized by salt bridges (mediated by K52/R79/R109) and hydrophobic interactions (involving F17). Functional validation through gel filtration chromatography revealed that the disruption of the dimerization interface via F17A/K52A/R79A mutations caused complete dissociation into monomers, establishing the essential role of TPR-mediated oligomerization in maintaining the structural stability of full-length OsSGT1. Yeast two-hybrid assays showed that the dimerization disruption of SGT1 mutants retained the interaction with OsHSP81-2 (an HSP90 ortholog) and OsRAR1, indicating that SGT1 oligomerization serves primarily as a structural stabilizer rather than a prerequisite for partner interaction. Evolutionary analysis through the sequence alignment of plant SGT1 proteins revealed the conservation of the dimerization interface residues. This study provides structural insights into the conserved molecular features of SGT1 proteins and highlights the functional significance of their oligomerization state.
ISSN:2073-4352

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