Cytokinin‐induced structural adaptability of a Lupinus luteus PR‐10 protein

Abstract

Plant pathogenesis‐related (PR) proteins of class 10 are the only group among the 17 PR protein families that are intracellular and cytosolic. Sequence conservation and the wide distribution of PR‐10 proteins throughout the plant kingdom are an indication of an indispensable function in plants, but their true biological role remains obscure. Crystal and solution structures for several homologues have shown a similar overall fold with a vast internal cavity which, together with structural similarities to the steroidogenic acute regulatory protein‐related lipid transfer domain and cytokinin‐specific binding proteins, strongly indicate a ligand‐binding role for the PR‐10 proteins. This article describes the structure of a complex between a classic PR‐10 protein [Lupinus luteus (yellow lupine) PR‐10 protein of subclass 2, LlPR‐10.2B] and N,N′‐diphenylurea, a synthetic cytokinin. Synthetic cytokinins have been shown in various bioassays to exhibit activity similar to that of natural cytokinins. The present 1.95 Å resolution crystallographic model reveals four N,N′‐diphenylurea molecules in the hydrophobic cavity of the protein and a degree of conformational changes accompanying ligand binding. The structural adaptability of LlPR‐10.2B and its ability to bind different cytokinins suggest that this protein, and perhaps other PR‐10 proteins as well, can act as a reservoir of cytokinin molecules in the aqueous environment of a plant cell.

Structure and Function of the Peanut Panallergen Ara h 8

“…The metal was identified as sodium, which is consistent with previous structural studies of PR-10 proteins (39). For example, an observed Na ϩ binding site overlaps very well with one of the sodium binding sites found in L1PR-10.2B (PDB code 3E85) originating from yellow lupine (40).…”

Structure‐based analysis of thermodynamic and mechanical properties of cavity‐containing proteins – case study of plant pathogenesis‐related proteins of class 10

“…This may indicate that the ligands of different PR-10 proteins can be of very different chemical character, a phenomenon that has already been noted in the literature [11]. According to this view, the PR-10 proteins could be regarded as versatile ligand binders, fulfilling perhaps quite diverse roles in small-molecule signalling and transport/storage.…”

The RNA Hydrolysis and the Cytokinin Binding Activities of PR-10 Proteins Are Differently Performed by Two Isoforms of the Pru p 1 Peach Major Allergen and Are Possibly Functionally Related

“…In this regard, it is interesting to note that, while all PR-10 proteins contain a highly conserved and stable b-sheet, they show structural variability in the a-helical content. In particular, the conformation of helix a3 determines the accessibility, the size, and the shape of the hydrophobic cavity that holds zeatin or other ligands (Biesiadka et al, 2002;Pasternak et al, 2006;Fernandes et al, 2008Fernandes et al, , 2009). …”