Arabidospsis thaliana PrRs (pinoresinol/lariciresinol reductases)
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'''3. Substrate selectivity''' | '''3. Substrate selectivity''' | ||
- | In contrast with AtPrR, IiPLR β4 loops are disorder regardless of the ligand state of the protein, indicating an influence in substrate selectivity and catalysis. The β4 loop amino-acid sequence differs by one residue between IiPLR and AtPrR: at the C-terminal end of the loop, Ser98 is substituted by Asn98 in ''A. thaliana''. The interaction between Asn98 and NADPH results in a position shift of the asparagine side chain, physically limiting the β4 loop's movement in PrR. Furthermore, due to a change in the amino-acid sequence from Val46 to Leu46 in PrR1, SBD is condensed and tighter, limiting the entrance and orientation of the substrate. In PrR2, the same result is observed, and although there is no change in aminoacid residue, Val46 is pushed further into SBD, possibly owing to different dimer orientation. Thus, it is suggested that aminoacid residues at position 46 and 98 are essential for substrate selectivity (Xiao et al., 2021). | + | In contrast with AtPrR, IiPLR β4 loops are disorder regardless of the ligand state of the protein, indicating an influence in substrate selectivity and catalysis. The β4 loop amino-acid sequence differs by one residue between IiPLR and AtPrR: at the C-terminal end of the loop, <scene name='10/1050287/98_e_nadph/2'>Ser98 is substituted by Asn98 in ''A. thaliana''</scene>. The interaction between Asn98 and NADPH results in a position shift of the asparagine side chain, physically limiting the β4 loop's movement in PrR. Furthermore, due to a change in the amino-acid sequence from Val46 to Leu46 in PrR1, SBD is condensed and tighter, limiting the entrance and orientation of the substrate. In PrR2, the same result is observed, and although there is no change in aminoacid residue, Val46 is pushed further into SBD, possibly owing to different dimer orientation. Thus, it is suggested that aminoacid residues at position 46 and 98 are essential for substrate selectivity (Xiao et al., 2021). |
[[Image:425 2019 3137 Fig2 HTML.png|600px]] | [[Image:425 2019 3137 Fig2 HTML.png|600px]] |
Revision as of 21:32, 2 June 2024
Página sobre a PrR1 e PrR2 de Arabidopsis feita por alunos da Biologia da USP São Paulo.
A. thaliana PrRs
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4. AtPrR expression
Understanding the pattern of expression of the PLR family is key in the study of lignans, considering that the diversity of these secondary metabolites is due to the action of these enzymes, but also to their expression pattern (Xiao et al., 2021; Markulin et al., 2019), which dictates where in the plants and when a certain lignan will be produced.
The pattern of expression of the PLRs varies from plant to plant and it can be altered by different stresses and hormones (Markunil et al., 2019). In the case of Arabidopsis thaliana, both PrR1 and PrR2 are expressed in root, but only PrR1 is also expressed in stem. Zhao and collaborators (2014) have shown by co-expression analysis that PrR1 might be related to the deposition of secondary cell wall, as it clustered with genes related to: lignification, hemicellulose biosynthesis, cellulose synthesis, etc. This possibility was reinforced by transactivation assays in which the trans-activators factors MYB46 and SND1, both related to the deposition of secondary cell wall, interacted with the PrR1 promoter. On other hand, PrR2 clustered with a different set of genes, been close to genes not related to secondary cell wall deposition, as well to genes related to lignification and to the formation of the casparian strip.
What might look contradictory is the fact that PrR1 and PrR2 are coexpressed with lignin related genes and that pinoresinol, the first substrate of the PLR enzymes, is synthetized by the dimerization of two coniferyl alcohols, onde of the monomers that constitute the lignin polymer. We could imagine that the production of lignans would compete for substrates with the biosynthesis of lignin, and therefore the coexpression mentioned would be questionable. Zhao and collaborators (2014) have shown that mutants of A. thaliana without the function of the PrR1 enzyme show lower content of lignin, meaning that, somehow the production of lignans is important for lignification and related to lignin polymerization.
5. References
- ↑ Xiao Y, Shao K, Zhou J, Wang L, Ma X, Wu D, Yang Y, Chen J, Feng J, Qiu S, Lv Z, Zhang L, Zhang P, Chen W. Structure-based engineering of substrate specificity for pinoresinol-lariciresinol reductases. Nat Commun. 2021 May 14;12(1):2828. PMID:33990581 doi:10.1038/s41467-021-23095-y
- ↑ Markulin L, Corbin C, Renouard S, Drouet S, Gutierrez L, Mateljak I, Auguin D, Hano C, Fuss E, Lainé E. Pinoresinol-lariciresinol reductases, key to the lignan synthesis in plants. Planta. 2019 Jun;249(6):1695-1714. PMID:30895445 doi:10.1007/s00425-019-03137-y
MARKULIN, L. et al. Pinoresinol–lariciresinol reductases, key to the lignan synthesis in plants. Planta, v. 249, n. 6, p. 1695–1714, 20 mar. 2019. PMID: 30895445. DOI: https://doi.org/10.1007/s00425-019-03137-y.
TOMOYUKI NAKATSUBO et al. Characterization of Arabidopsis thaliana Pinoresinol Reductase, a New Type of Enzyme Involved in Lignan Biosynthesis. Journal of Biological Chemistry, v. 283, n. 23, p. 15550–15557, 1 jun. 2008. PMID: 18347017. DOI: https://doi.org/10.1074%2Fjbc.M801131200.
WANG, L. et al. Review of lignans from 2019 to 2021: Newly reported compounds, diverse activities, structure-activity relationships and clinical applications. Phytochemistry, v. 202, p. 113326–113326, 1 out. 2022.
WARD, R. Lignans, neolignans and related compounds. v. 16, n. 1, p. 75–96, 1 jan. 1999. doi: https://doi.org/10.1039/A705992B
XIAO, Y. et al. Structure-based engineering of substrate specificity for pinoresinol-lariciresinol reductases. Nature communications, v. 12, n. 1, 14 maio 2021. PMID: 33990581. DOI: https://doi.org/10.1038/s41467-021-23095-y.
ZHAO, Q. et al. Pinoresinol reductase 1 impacts lignin distribution during secondary cell wall biosynthesis in Arabidopsis. Phytochemistry, v. 112, p. 170–178, 1 abr. 2015. PMID: 25107662. DOI: https://doi.org/10.1016/j.phytochem.2014.07.008.
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