Xanthomonas oryzae pv. oryzae XopQ protein suppresses rice immune responses through interaction with two 14-3-3 proteins but its phospho-null mutant induces rice immune responses and interacts with another 14-3-3 protein

Many bacterial phytopathogens employ effectors secreted through the type-III secretion system to suppress plant innate immune responses. The Xanthomonas type-III secreted non-TAL effector protein Xanthomonas outer protein Q (XopQ) exhibits homology to nucleoside hydrolases. Previous work indicated that mutations which affect the biochemical activity of XopQ fail to affect its ability to suppress rice innate immune responses, suggesting that the effector might be acting through some other pathway or mechanism. In this study, we show that XopQ interacts in yeast and in planta with two rice 14-3-3 proteins, Gf14f and Gf14g. A serine to alanine mutation (S65A) of a 14-3-3 interaction motif in XopQ abolishes the ability of XopQ to interact with the two 14-3-3 proteins and to suppress innate immunity. Surprisingly, the S65A mutant gains the ability to interact with a third 14-3-3 protein that is a negative regulator of innate immunity. The XopQS65A mutant is an inducer of rice immune responses and this property is dominant over the wild-type function of XopQ. Taken together, these results suggest that XopQ targets the rice 14-3-3 mediated immune response pathway and that its differential phosphorylation might enable interaction with alternative 14-3-3 proteins.     

Inhibition of MAPK signaling pathways by VopA from Vibrio parahaemolyticus

During infection, bacterial pathogens utilize a type III secretion system to inject effectors into the cytoplasm of a target cell where they disrupt the defense system of the host cell. Vibrio parahaemolyticus, a causative agent of gastroenteritis endemic in Southeast Asia, has a type III secretion system that encodes a novel member of the YopJ-like protein effector family, VopA (Vibrio outer protein A). Our studies revealed that Vibrio VopA encodes an evolutionarily conserved activity that is extremely potent and requires an intact catalytic site to abrogate signaling pathways in a manner distinct from that of other YopJ-like effectors. We observed that VopA efficiently inhibits the MAPK signaling pathways but not the NFkappaB pathway in mammalian cells. When expressed in yeast, VopA induces a growth arrest phenotype and also blocks yeast MAPK signaling pathways. Our observations provide insight into the immense diversity of targets utilized by YopJ-like effectors to manipulate eukaryotic signaling machineries that are important for the response and survival of the host cell during infection and/or symbiosis.     

Intrinsically disordered proteins as molecular shields

The broad family of LEA proteins are intrinsically disordered proteins (IDPs) with several potential roles in desiccation tolerance, or anhydrobiosis, one of which is to limit desiccation-induced aggregation of cellular proteins. We show here that this activity, termed molecular shield function, is distinct from that of a classical molecular chaperone, such as HSP70 - while HSP70 reduces aggregation of citrate synthase (CS) on heating, two LEA proteins, a nematode group 3 protein, AavLEA1, and a plant group 1 protein, Em, do not; conversely, the LEA proteins reduce CS aggregation on desiccation, while HSP70 lacks this ability. There are also differences in interaction with client proteins - HSP70 can be co-immunoprecipitated with a polyglutamine-containing client, consistent with tight complex formation, whereas the LEA proteins can not, although a loose interaction is observed by F?rster resonance energy transfer. In a further exploration of molecular shield function, we demonstrate that synthetic polysaccharides, like LEA proteins, are able to reduce desiccation-induced aggregation of a water-soluble proteome, consistent with a steric interference model of anti-aggregation activity. If molecular shields operate by reducing intermolecular cohesion rates, they should not protect against intramolecular protein damage. This was tested using the monomeric red fluorescent protein, mCherry, which does not undergo aggregation on drying, but the absorbance and emission spectra of its intrinsic fluorophore are dramatically reduced, indicative of intramolecular conformational changes. As expected, these changes are not prevented by AavLEA1, except for a slight protection at high molar ratios, and an AavLEA1-mCherry fusion protein is damaged to the same extent as mCherry alone. A recent hypothesis proposed that proteomes from desiccation-tolerant species contain a higher degree of disorder than intolerant examples, and that this might provide greater intrinsic stability, but a bioinformatics survey does not support this, since there are no significant differences in the degree of disorder between desiccation tolerant and intolerant species. It seems clear therefore that molecular shield function is largely an intermolecular activity implemented by specialist IDPs, distinct from molecular chaperones, but with a role in proteostasis.     

Complete Genome Sequence of Newcastle Disease Virus Mesogenic Vaccine Strain R2B from India

Mesogenic vaccine strains of Newcastle disease virus (NDV) are widely used in many countries of Asia and Africa to control the Newcastle disease of poultry. In India, the mesogenic strain R2B was introduced in 1945; it protects adult chickens that have been preimmunized with a lentogenic vaccine virus and provides long-lasting immunity. In this article, we report the complete genome sequence of the hitherto unsequenced Indian vaccine virus strain R2B. The viral genome is 15,186 nucleotides in length and contains the polybasic amino acid motif in the fusion protein cleavage site, indicating that this vaccine strain has evolved from a virulent virus. Phylogenetic analysis of this mesogenic vaccine virus classified it with the viruses belonging to genotype III of the class cluster II of NDV.     

Copper(II) import and reduction are dependent on His-Met clusters in the extracellular amino terminus of human copper transporter-1

Copper(I) is an essential metal for all life forms. Though Cu(II) is the most abundant and stable state, its reduction to Cu(I) via an unclear mechanism is prerequisite for its bioutilization. In eukaryotes, the copper transporter-1 (CTR1) is the primary high-affinity copper importer, although its mechanism and role in Cu(II) reduction remain uncharacterized. Here we show that extracellular amino-terminus of human CTR1 contains two methionine-histidine clusters and neighboring aspartates that distinctly bind Cu(I) and Cu(II) preceding its import. We determined that hCTR1 localizes at the basolateral membrane of polarized MDCK-II cells and that its endocytosis to Common-Recycling-Endosomes is regulated by reduction of Cu(II) to Cu(I) and subsequent Cu(I) coordination by the methionine cluster. We demonstrate the transient binding of both Cu(II) and Cu(I) during the reduction process is facilitated by aspartates that also act as another crucial determinant of hCTR1 endocytosis. Mutating the first Methionine cluster (⁷Met-Gly-Met⁹) and Asp¹³ abrogated copper uptake and endocytosis upon copper treatment. This phenotype could be reverted by treating the cells with reduced and nonreoxidizable Cu(I). We show that histidine clusters, on other hand, bind Cu(II) and are crucial for hCTR1 functioning at limiting copper. Finally, we show that two N-terminal His-Met-Asp clusters exhibit functional complementarity, as the second cluster is sufficient to preserve copper-induced CTR1 endocytosis upon complete deletion of the first cluster. We propose a novel and detailed mechanism by which the two His-Met-Asp residues of hCTR1 amino-terminus not only bind copper, but also maintain its reduced state, crucial for intracellular uptake.     

A systemic insight into astrocytoma biology across different grades

Astrocytomas are the most common type of brain tumors, which originate from glial cells, and are classified into specific grades based on their histopathological behavior. To develop precise therapeutic strategies for the disease, it is important to identify the molecular signatures specific to each grade as well as the key factors responsible for the transition from one grade to the next. In this study, we have taken a systems approach to investigate the gene expression profiles of each grades of the disease by mapping shortest paths of gene interaction in each grade and also between one grade and the next. Module core genes govern the topology of these networks and serve as important functional players in each grade as well as help in grade transition events. Shortlisted among these module core genes are well-characterized players of glioma as well as novel molecules (32 grade-specific genes and 15 grade transition–specific genes), which influence important prooncogenic functions but have not been linked to glioma biology yet. These module core genes provide interesting insight into the biology of astrocytic tumors and are potential therapeutic targets for astrocytoma.     

Cadmium bioaccumulation in Lamellidens marginalis and human health risk assessment: A case study in India

Abstract

Lamellidens marginalis is an easily available food with high nutritive value. The present study is based on the East Kolkata Wetlands (EKW), India that produces mussels, consumed by human. Thus, the study of heavy metal pollution in the wastewater and mussel, and its transport to human is considered to be need of the hour to assess the health risk to human. The present study focuses on the cadmium accumulation in the outer exposed organs and the internal organs of L. marginalis. The mussel, sediment, and water were collected from the field and analyzed in the laboratory. The environmental factors were analyzed in situ. The survey work was conducted among the consumers of mussel around the EKW to predict the effect of cadmium on human. The result showed that the cadmium concentration of water was relatively important for the bioaccumulation process in L. marginalis. People having low level of income and age above forty, living adjoining the EKW were at high risk of cadmium pollution. The hazard quotient value of the above group was highest among all the groups across age and income. A ‘biofilter’ technique was suggested to mitigate the biomagnification of cadmium at the EKW.