Structure Report for: 5DNU

Xu, Y., Miyakawa, T., Nakamura, A., Tanokura, M.

Title: Structural basis of unique ligand specificity of KAI2-like protein from parasitic weed Striga hermonthica
Xu Y, Miyakawa T, Nakamura H, Nakamura A, Imamura Y, Asami T, Tanokura M
Ref: Sci Rep, 6:31386, 2016 : PubMed
Abstract


ESTHER: Xu_2016_Sci.Rep_6_31386
PubMedSearch: Xu 2016 Sci.Rep 6 31386
PubMedID: 27507097
Gene_locus related to this paper: strhe-ShHTL3

Abstract

The perception of two plant germination inducers, karrikins and strigolactones, are mediated by the proteins KAI2 and D14. Recently, KAI2-type proteins from parasitic weeds, which are possibly related to seed germination induced by strigolactone, have been classified into three clades characterized by different responses to karrikin/strigolactone. Here we characterized a karrikin-binding protein in Striga (ShKAI2iB) that belongs to intermediate-evolving KAI2 and provided the structural bases for its karrikin-binding specificity. Binding assays showed that ShKAI2iB bound karrikins but not strigolactone, differing from other KAI2 and D14. The crystal structures of ShKAI2iB and ShKAI2iB-karrikin complex revealed obvious structural differences in a helix located at the entry of its ligand-binding cavity. This results in a smaller closed pocket, which is also the major cause of ShKAI2iB's specificity of binding karrikin. Our structural study also revealed that a few non-conserved amino acids led to the distinct ligand-binding profile of ShKAI2iB, suggesting that the evolution of KAI2 resulted in its diverse functions.