Herbicide/Quinone Binding Interactions in Photosystem II

Many inhibitors prevent the oxidation of the primary electron-accepting quinone (QA) by the secondary quinone (Qв) in photosystem II by displacement of Qв from its binding site. On the other hand, plastoquinone-1 and 6-azido-5-decyl-2,3-dim ethoxy-p-benzoquinone displace herbicides. Binding studies show the herbicide/quinone interaction to be (apparently) competitive.The herbicide binding is influenced differentially by various treatments. In this paper it is shown that the affinity of, for example, bromoxynil is decreased by thylakoid unstacking or by light-or reductant-induced reduction of certain thylakoid components, whereas atrazine affinity remains unchanged. Furthermore, absence of HCO-3 in the presence of form ate leads to an affinity decrease of bromoxynil and atrazine, but to an increase in i-dinoseb affinity. Other differential photosystem II herbicide effects are known from the literature.Since different and unrelated groups of Q-A oxidation inhibitors have been found, and because of the above-mentioned dissimilarities in binding characteristics for different inhibitor groups, the hypothesis of non-identical, but “overlapping” binding sites for different herbicide groups and the native quinone must be more extensively defined. In this manuscript we evaluate both the competitive herbicide/quinone binding model, and a model in which binding of one ligand alters the protein conformation resulting in a dramatic decrease in the binding affinity of ligands from other chemical groups; in this model ligands from the same or related chemical groups bind competitively. Thus, the latter model proposes that only one herbicide or quinone molecule can be bound with high affinity to the herbicide/quinone binding environment, but it depends on the chemical structure of the ligands whether the binding interaction between two ligands is truly competitive or more indirect (allosteric), mediated through the protein conformation

Toward an Open-Access Global Database for Mapping, Control, and Surveillance of Neglected Tropical Diseases

There is growing interest in the scientific community, health ministries, and other organizations to control and eventually eliminate neglected tropical diseases (NTDs). Control efforts require reliable maps of NTD distribution estimated from appropriate models and survey data on the number of infected people among those examined at a given location. This kind of data is often available in the literature as part of epidemiological studies. However, an open-access database compiling location-specific survey data does not yet exist. We address this problem through a systematic literature review, along with contacting ministries of health, and research institutions to obtain disease data, including details on diagnostic techniques, demographic characteristics of the surveyed individuals, and geographical coordinates. All data were entered into a database which is freely accessible via the Internet (http://www.gntd.org). In contrast to similar efforts of the Global Atlas of Helminth Infections (GAHI) project, the survey data are not only displayed in form of maps but all information can be browsed, based on different search criteria, and downloaded as Excel files for further analyses. At the beginning of 2011, the database included over 12,000 survey locations for schistosomiasis across Africa, and it is continuously updated to cover other NTDs globally

HIV-1 Neutralization Profile and Plant-Based Recombinant Expression of Actinohivin, an Env Glycan-Specific Lectin Devoid of T-Cell Mitogenic Activity

The development of a topical microbicide blocking the sexual transmission of HIV-1 is urgently needed to control the global HIV/AIDS pandemic. The actinomycete-derived lectin actinohivin (AH) is highly specific to a cluster of high-mannose-type glycans uniquely found on the viral envelope (Env). Here, we evaluated AH's candidacy toward a microbicide in terms of in vitro anti-HIV-1 activity, potential side effects, and recombinant producibility. Two validated assay systems based on human peripheral blood mononuclear cell (hPBMC) infection with primary isolates and TZM-bl cell infection with Env-pseudotyped viruses were employed to characterize AH's anti-HIV-1 activity. In hPMBCs, AH exhibited nanomolar neutralizing activity against primary viruses with diverse cellular tropisms, but did not cause mitogenicity or cytotoxicity that are often associated with other anti-HIV lectins. In the TZM-bl-based assay, AH showed broad anti-HIV-1 activity against clinically-relevant, mucosally transmitting strains of clades B and C. By contrast, clade A viruses showed strong resistance to AH. Correlation analysis suggested that HIV-1′s AH susceptibility is significantly linked to the N-glycans at the Env C2 and V4 regions. For recombinant (r)AH expression, we evaluated a tobacco mosaic virus-based system in Nicotiana benthamiana plants as a means to facilitate molecular engineering and cost-effective mass production. Biochemical analysis and an Env-mediated syncytium formation assay demonstrated high-level expression of functional rAH within six days. Taken together, our study revealed AH's cross-clade anti-HIV-1 activity, apparent lack of side effects common to lectins, and robust producibility using plant biotechnology. These findings justify further efforts to develop rAH toward a candidate HIV-1 microbicide

The Cyst Nematode SPRYSEC Protein RBP-1 Elicits Gpa2- and RanGAP2-Dependent Plant Cell Death

Plant NB-LRR proteins confer robust protection against microbes and metazoan parasites by recognizing pathogen-derived avirulence (Avr) proteins that are delivered to the host cytoplasm. Microbial Avr proteins usually function as virulence factors in compatible interactions; however, little is known about the types of metazoan proteins recognized by NB-LRR proteins and their relationship with virulence. In this report, we demonstrate that the secreted protein RBP-1 from the potato cyst nematode Globodera pallida elicits defense responses, including cell death typical of a hypersensitive response (HR), through the NB-LRR protein Gpa2. Gp-Rbp-1 variants from G. pallida populations both virulent and avirulent to Gpa2 demonstrated a high degree of polymorphism, with positive selection detected at numerous sites. All Gp-RBP-1 protein variants from an avirulent population were recognized by Gpa2, whereas virulent populations possessed Gp-RBP-1 protein variants both recognized and non-recognized by Gpa2. Recognition of Gp-RBP-1 by Gpa2 correlated to a single amino acid polymorphism at position 187 in the Gp-RBP-1 SPRY domain. Gp-RBP-1 expressed from Potato virus X elicited Gpa2-mediated defenses that required Ran GTPase-activating protein 2 (RanGAP2), a protein known to interact with the Gpa2 N terminus. Tethering RanGAP2 and Gp-RBP-1 variants via fusion proteins resulted in an enhancement of Gpa2-mediated responses. However, activation of Gpa2 was still dependent on the recognition specificity conferred by amino acid 187 and the Gpa2 LRR domain. These results suggest a two-tiered process wherein RanGAP2 mediates an initial interaction with pathogen-delivered Gp-RBP-1 proteins but where the Gpa2 LRR determines which of these interactions will be productive

Technology progression in plants used for food and medicine

The food industry has a history and scientists have faced difficult decisions before, and, as a society, we have made good and bad choices in the past. One man’s noxious weed may be another’s cure for depression, and there can also be serious implications if we don’t consider human behavior. We have seen a number of cases recently of serious complications involving mixtures of ingredients—with some combined on purpose and others inadvertently. There is a need for uniformity and standardization to reduce risks in the alternative health-care area, including the need for clinical trials and a need for continued vigilance and containment of genetically modified (GM) crops

Crop biotechnology in the service of medical and veterinary science

Various research laboratories have experimented with the use of plants for “biomanufacturing” of specialty products. These approaches utilize transgenic plants created to accumulate high value proteins/enzymes of potential pharmaceutical value such as vaccines

Agrobacterium tumefaciens transformation of Musa species

Methods are provided for transforming Musa plants. In particular, methods for wounding meristematic Musa plant tissue to facilitate access of Agrobacterium tumefaciens comprising genetically-engineered T-DNA is provided. The methods may be used to transform the plant to produce pharmaceutical products or to alter the phenotypic trait of the fruit of the plant.U

Agrobacterium tumefaciens transformation of Musa species

Methods are provided for transforming Musa plants. In particular, methods for wounding meristematic Musa plant tissue to facilitate access of Agrobacterium tumefaciens comprising genetically-engineered T-DNA is provided. The methods may be used to transform the plant to produce pharmaceutical products or to alter the phenotypic trait of the fruit of the plant.U