Febs Letters

doi: 10.1016/S0014-5793(13)00750-3pmid: N/A

Wieland, Felix; Perham, Richard

doi: 10.1016/j.febslet.2013.09.025pmid: 24076027

Nath, Krishna; Jajoo, Anjana; Poudyal, Roshan Sharma; Timilsina, Rupak; Park, Yu Shin; Aro, Eva-Mari; Nam, Hong Gil; Lee, C.-H.

doi: 10.1016/j.febslet.2013.09.015pmid: 24056074

Photosystem II (PSII) is vulnerable to high light (HL) illumination resulting in photoinhibition. In addition to photoprotection mechanisms, plants have developed an efficient PSII repair mechanism to save themselves from irreversible damage to PSII under abiotic stresses including HL illumination. The phosphorylation/dephosphorylation cycle along with subsequent degradation of photodamaged D1 protein to be replaced by the insertion of a newly synthesized copy of D1 into the PSII complex, is the core function of the PSII repair cycle. The exact mechanism of this process is still under discussion. We describe the recent progress in identifying the kinases, phosphatases and proteases, and in understanding their involvement in the maintenance of thylakoid structure and the quality control of proteins by PSII repair cycle during photoinhibition.

Nihira, Takanori; Saito, Yuka; Chiku, Kazuhiro; Kitaoka, Motomitsu; Ohtsubo, Ken‧ichi; Nakai, Hiroyuki

doi: 10.1016/j.febslet.2013.08.038pmid: 24021648

We discovered a potassium ion‐dependent trehalose phosphorylase (Bsel_1207) belonging to glycoside hydrolase family 65 from halophilic Bacillus selenitireducens MLS10. Under high potassium ion concentrations, the recombinant Bsel_1207 produced in Escherichia coli existed as an active dimeric form that catalyzed the reversible phosphorolysis of trehalose in a typical sequential bi bi mechanism releasing β‐d‐glucose 1‐phosphate and d‐glucose. Decreasing potassium ion concentrations significantly reduced thermal and pH stabilities, leading to formation of inactive monomeric Bsel_1207.

Imperi, Francesco; Visca, Paolo

doi: 10.1016/j.febslet.2013.08.039pmid: 24042050

The peptidic siderophore pyoverdine is the primary iron uptake system of fluorescent pseudomonads, and a virulence factor in the opportunistic pathogen Pseudomonas aeruginosa. Pyoverdine biogenesis is a co‐ordinate process requiring several precursor‐generating enzymes and large nonribosomal peptide synthetases (NRPSs) in the cytoplasm, followed by extracytoplasmic maturation. By using cell fractionation, protein–protein interaction, and in vivo labeling assays we obtained evidence that, in P. aeruginosa, pyoverdine NRPSs assemble with precursor‐generating enzymes into a membrane‐bound multi‐enzymatic complex, for which we propose the name “siderosome”. The pyoverdine biogenetic complex represents a novel example of subcellular compartmentalization of a secondary metabolic pathway in prokaryotes.

Seerapu, Himabindu Reddy; Borthakur, Susmita; Kong, Nathan; Agrawal, Sudesh; Drazba, Judy; Vasanji, Amit; Fantin, Alessandro; Ruhrberg, Christiana; Buck, Matthias; Horowitz, Arie

doi: 10.1016/j.febslet.2013.08.040pmid: 24021649

Guerra, Damian D.; Pratelli, Réjane; Kraft, Edward; Callis, Judy; Pilot, Guillaume

doi: 10.1016/j.febslet.2013.08.045pmid: 24036454

Plant LOSS OF GDU 2 (LOG2) and Mammalian Mahogunin Ring Finger 1 (MGRN1) proteins are RING‐type E3 ligases sharing similarity N‐terminal to the RING domain. Deletion of this region disrupts the interaction of LOG2 with the plant membrane protein GLUTAMINE DUMPER1 (GDU1). Phylogenetic analysis identified two clades of LOG2/MGRN1‐like proteins in vertebrates and plants. The ability of MGRN1 to functionally replace LOG2 was tested. MGRN1 ubiquitylates GDU1 in vitro and can partially substitute for LOG2 in the plant, partially restoring amino acid resistance to a GDU1‐myc over‐expression, log2‐2 background. Altogether, these results suggest a conserved function for the N‐terminal domain in evolution.

Peinado, Juan R.; Sami, Furqan; Rajpurohit, Nina; Lindberg, Iris

doi: 10.1016/j.febslet.2013.09.006pmid: 24042052

The deposition of fibrillated human islet β‐cell peptide islet amyloid polypeptide (hIAPP) into amyloid plaques is characteristic of the pathogenesis of islet cell death during type 2 diabetes. We investigated the effects of the neuroendocrine secretory proteins 7B2 and proSAAS on hIAPP fibrillation in vitro and on cytotoxicity. In vitro, 21‐kDa 7B2 and proSAAS blocked hIAPP fibrillation. Structure–function studies showed that a central region within 21‐kDa 7B2 is important in this effect and revealed the importance of the N‐terminal region of proSAAS. Both chaperones blocked the cytotoxic effects of exogenous hIAPP on Rin5f cells; 7B2 generated by overexpression was also effective. ProSAAS and 7B2 may perform a chaperone role as secretory anti‐aggregants in normal islet cell function and in type 2 diabetes.

Kaplan-Türköz, Burcu; Koelblen, Thomas; Felix, Christine; Candusso, Marie-Pierre; O‧Callaghan, David; Vergunst, Annette C.; Terradot, Laurent

doi: 10.1016/j.febslet.2013.09.007pmid: 24076024

BtpA/Btp1/TcpB is a virulence factor produced by Brucella species that possesses a Toll interleukin‐1 receptor (TIR) domain. Once delivered into the host cell, BtpA interacts with MyD88 to interfere with TLR signalling and modulates microtubule dynamics. Here the crystal structure of the BtpA TIR domain at 3.15 Å is presented. The structure shows a dimeric arrangement of a canonical TIR domain, similar to the Paracoccus denitrificans Tir protein but secured by a unique long N‐terminal α‐tail that packs against the TIR:TIR dimer. Structure‐based mutations and multi‐angle light scattering experiments characterized the BtpA dimer conformation in solution. The structure of BtpA will help with studies to understand the mechanisms involved in its interactions with MyD88 and with microtubules.

Guo, Kunyuan; Bu, Yuanyuan; Takano, Tetsuo; Liu, Shenkui; Zhang, Xinxin

doi: 10.1016/j.febslet.2013.09.019pmid: 24076026

AtCYSb physically interacts with AtCaN2 by two hybrid (View interaction)