Cell entry of a host targeting protein of oomycetes requires gp96

This work is supported by the [European Community’s] Seventh Framework Programme [FP7/2007–2013] under grant agreement no. [238550] (L.L., J.D.-U., C.J.S., P.v.W.); BBSRC [BBE007120/1, BB/J018333/1 and BB/G012075/1] (F.T., I.d.B., C.J.S., S.W., P.v.W.); Newton Global Partnership Award [BB/N005058/1] (F.T., P.v.W.), the University of Aberdeen (A.D.T., T.R., C.J.S., P.v.W.) and Deutsche Forschungsgemeinschaft [CRC1093] (P.B., T.S.). We would like to acknowledge the Ministry of Higher Education Malaysia for funding INA. We would like to thank Brian Haas for his bioinformatics support. We would like to acknowledge Neil Gow and Johannes van den Boom for critical reading of the manuscript. We would like to acknowledge Svetlana Rezinciuc for technical help with pH-studies.Peer reviewedPublisher PD

Cytoskeletal protein kinases: titin and its relations in mechanosensing

Titin, the giant elastic ruler protein of striated muscle sarcomeres, contains a catalytic kinase domain related to a family of intrasterically regulated protein kinases. The most extensively studied member of this branch of the human kinome is the Ca2+–calmodulin (CaM)-regulated myosin light-chain kinases (MLCK). However, not all kinases of the MLCK branch are functional MLCKs, and about half lack a CaM binding site in their C-terminal autoinhibitory tail (AI). A unifying feature is their association with the cytoskeleton, mostly via actin and myosin filaments. Titin kinase, similar to its invertebrate analogue twitchin kinase and likely other “MLCKs”, is not Ca2+–calmodulin-activated. Recently, local protein unfolding of the C-terminal AI has emerged as a common mechanism in the activation of CaM kinases. Single-molecule data suggested that opening of the TK active site could also be achieved by mechanical unfolding of the AI. Mechanical modulation of catalytic activity might thus allow cytoskeletal signalling proteins to act as mechanosensors, creating feedback mechanisms between cytoskeletal tension and tension generation or cellular remodelling. Similar to other MLCK-like kinases like DRAK2 and DAPK1, TK is linked to protein turnover regulation via the autophagy/lysosomal system, suggesting the MLCK-like kinases have common functions beyond contraction regulation

Time-resolved dual transcriptomics reveal early induced Nicotiana benthamiana root genes and conserved infection-promoting Phytophthora palmivora effectors

BACKGROUND: Plant-pathogenic oomycetes are responsible for economically important losses in crops worldwide. Phytophthora palmivora, a tropical relative of the potato late blight pathogen, causes rotting diseases in many tropical crops including papaya, cocoa, oil palm, black pepper, rubber, coconut, durian, mango, cassava and citrus. Transcriptomics have helped to identify repertoires of host-translocated microbial effector proteins which counteract defenses and reprogram the host in support of infection. As such, these studies have helped in understanding how pathogens cause diseases. Despite the importance of P. palmivora diseases, genetic resources to allow for disease resistance breeding and identification of microbial effectors are scarce. RESULTS: We employed the model plant Nicotiana benthamiana to study the P. palmivora root infections at the cellular and molecular levels. Time-resolved dual transcriptomics revealed different pathogen and host transcriptome dynamics. De novo assembly of P. palmivora transcriptome and semi-automated prediction and annotation of the secretome enabled robust identification of conserved infection-promoting effectors. We show that one of them, REX3, suppresses plant secretion processes. In a survey for early transcriptionally activated plant genes we identified a N. benthamiana gene specifically induced at infected root tips that encodes a peptide with danger-associated molecular features. CONCLUSIONS: These results constitute a major advance in our understanding of P. palmivora diseases and establish extensive resources for P. palmivora pathogenomics, effector-aided resistance breeding and the generation of induced resistance to Phytophthora root infections. Furthermore, our approach to find infection-relevant secreted genes is transferable to other pathogen-host interactions and not restricted to plants.This work was supported by the Gatsby Charitable Foundation (RG62472), by the Royal Society (RG69135) and by the European Research Council (ERC-2014-STG, H2020, 637537)

Mechanisms of wavelength tuning in the rod opsins of deep-sea fishes.

The main object of this study was to investigate the molecular basis for changes in the spectral sensitivity of the visual pigments of deep-sea fishes. The four teleost species studied, Hoplostethus mediterraneus, Cataetyx laticeps, Gonostoma elongatum and Histiobranchus bathybius, are phylogenetically distant from each other and live at depths ranging from 500 to almost 5000 m. A single fragment of the intronless rod opsin gene was PCR-amplified from each fish and sequenced. The wavelength of peak sensitivity for the rod visual pigments of the four deep-sea species varies from 483 nm in H. mediterraneus and G. elongatum to 468 nm in C. laticeps. Six amino acids at sites on the inner face of the chromophore-binding pocket formed by the seven transmembrane a-helices are identified as candidates for spectral tuning. Substitutions at these sites involve either a change of charge, or a gain or loss of a hydroxyl group. Two of these, at positions 83 and 292, are consistently substituted in the visual pigments of all four species and are likely to be responsible for the shortwave sensitivity of the pigments. Shifts to wavelengths shorter than 480 nm may involve substitution at one or more of the remaining four sites. None of the modifications found in the derived sequences of these opsins suggest functional adaptations, such as increased content of hydroxyl-bearing or proline residues, to resist denaturation by the elevated hydrostatic pressures of the deep sea. Phylogenetic evidence for the duplication of the rod opsin gene in the Anguilliform lineage is presented