Structure of a yellow lupin pathogenesis-related PR-10 protein belonging to a novel subclass

Abstract

Pathogenesis-related (PR) proteins of class 10 are abundant in higher plants. Some of these proteins are induced under stress conditions as part of the plant defence mechanism. Other homologues are developmentally regulated and their expression varies in different plant organs. The PR-10 proteins are encoded by multigene families, have a weight of about 17 kDa and are found in the cytosol. In yellow lupin, nine different homologues have been identified and divided into two subclasses, LlPR-10.1 and LlPR-10.2. Within each subclass the sequence identity is about 75-91%, while across the subclasses it is only 59-60%. Here, the crystal structure of a yellow lupin PR-10 protein from the second subclass, LlPR-10.2A, is presented. The structure was solved by molecular replacement and refined to R = 0.205 using 1.9 A resolution data. The general fold of LlPR-10.2A resembles that of the other PR-10 proteins and consists of a long C-terminal alpha-helix surrounded by a seven-stranded antiparallel beta-sheet, with two shorter alpha-helices located between strands beta1 and beta2. The most variable part of the structure, the C-terminal helix, is strongly kinked towards the beta-sheet core in both LlPR-10.2A molecules present in the asymmetric unit. This unexpected feature reduces the size of the hydrophobic cavity observed in other PR-10 proteins that is reported to be the ligand-binding site. As in other PR-10 structures, a surface loop located near the entrance to the cavity shows very high structural conservation and stability despite the high glycine content in its sequence.

Crystal Structure of Vigna radiata Cytokinin-Specific Binding Protein in Complex with Zeatin

“…For instance, ANS (8-anilino-1-naphthalenesulfonic acid) displacement assays revealed that a birch (Betula verrucosa) pollen PR-10 protein (Betv1) may bind many physiologically relevant ligands (Mogensen et al, 2002). It has been suggested that the ligand binding function of PR-10 proteins might be controlled by the sequence and conformation of helix a3 (Pasternak et al, 2005). In agreement with these speculations is the observation (A) Selected purine-and urea-type cytokinins.…”

“…Helix a3 is generally the most diverse fragment also among classic PR-10 proteins (Biesiadka et al, 2002). The helices differ not only in conformation, with the most drastic example furnished by Lupinus luteus (Ll) PR-10.2A, in which the helix is kinked by 608 (Pasternak et al, 2005), but also in position, as in Betv1, in which the entire helix is shifted about one coil along its axis. It has been postulated that the variability of helix a3 has evolved as a way of regulating the specificity of the numerous PR-10 proteins toward their ligands through changes in the volume and shape of the binding cavity.…”

“…They have been implicated in plant defense and development programs, but their precise function is not known despite the accumulating structural data (Gajhede et al, 1996;Neudecker et al, 2001;Biesiadka et al, 2002;Pasternak et al, 2005;Schirmer et al, 2005). Based on very low sequence identity (<20%) with classic PR-10 proteins, it has been hypothesized that proteins belonging to the CSBP family might also fall into the PR-10 structural class.…”

“…1105/tpc.105.037119 demonstrated to play a role in plant development and during pathogen infection (van Loon and van Strien, 1999). To date, the structures of six plant PR-10 proteins have been reported (Gajhede et al, 1996;Neudecker et al, 2001;Biesiadka et al, 2002;Pasternak et al, 2005;Schirmer et al, 2005). The PR-10 fold consists of a curved b-sheet and a long C-terminal a-helix (a3), which enclose a large cavity within the protein core.…”

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

“…This is revealed by the structures of a number of PR-10 proteins obtained by NMR and x-ray crystallography, such as Bet v 1 from birch (Betula spp. ; Gajhede et al, 1996;Markovic-Housley et al, 2003), four isoforms of LlPR10 from yellow lupin (Lupinus luteus; Biesiadka et al, 2002;Pasternak et al, 2005;Fernandes et al, 2008), VrCSBP (cytokininspecific binding protein) from mung bean (Vigna radiata; Pasternak et al, 2006), Pru av 1 from cherry (Prunus avium; Neudecker et al, 2001), and Ap g 1 from celery (Apium graveolens; Schirmer et al, 2005).…”