Insights into the structure–function relationship of brown plant hopper resistance protein,Bph14 of rice plant: a computational structural biology approach

Brown plant hopper (BPH) is one of the major destructive insect pests of rice, causing severe yield loss. Thirty-two BPH resistance genes have been identified in cultivated and wild species of rice Although, molecular mechanism of rice plant resistance against BPH studied through map-based cloning, due to non-existence of NMR/crystal structures of Bph14 protein, recognition of leucine-rich repeat (LRR) domain and its interaction with different ligands are poorly understood. Thus, in the present study, in silico approach was adopted to predict three-dimensional structure of LRR domain of Bph14 using comparative modelling approach followed by interaction study with jasmonic and salicylic acids. LRR domain along with LRR-jasmonic and salicylic acid complexes were subjected to dynamic simulation using GROMACS, individually, for energy minimisation and refinement of the structure. Final binding energy of jasmonic and salicylic acid with LRR domain was calculated using MM/PBSA. Free-energy landscape analysis revealed that overall stability of LRR domain of Bph14 is not much affected after forming complex with jasmonic and salicylic acid. MM/PBSA analysis revealed that binding affinities of LRR domain towards salicylic acid is higher as compared to jasmonic acid. Interaction study of LRR domain with salicylic acid and jasmonic acid reveals that THR987 of LRR form hydrogen bond with both complexes. Thus, THR987 plays active role in the Bph14 and phytochemical interaction for inducing resistance in rice plant against BPH. In future, Bph14 gene and phytochemicals could be used in BPH management and development of novel resistant varieties for increasing rice yield.     

Identification of a single and non-essential cysteine residue in dextransucrase of Leuconostoc mesenteroides NRRL B-512F

Amino acid analysis of purified dextransucrase (sucrose: 1,6-α-D-glucan 6-α-D-glucosyltransferase EC 2.4.1.5) from Leuconostoc mesenteroides NRRL B-512F was carried out. The enzyme is virtually devoid of cysteine residue there being only one cysteine residue in the whole enzyme molecule comprising over 1500 amino acid residues. The enzyme is rich in acidic amino acid residues. The number of amino acid residues was calculated based on the molecular weight of 188,000 (Goyal and Katiyar 1994). Amino sugars were not found, implying that the enzyme is not a glycoprotein. It has been shown earlier that the cysteine residue in dextransucrase is not essential for enzyme activity (Goyal and Katiyar 1998). The presence of only one cysteine residue per enzyme molecule illustrates that its tertiary structure is solely dependent on other types of non-covalent interactions such as hydrogen bonding, ionic and nonpolar hydrophobic interactions.     

Murburn posttranslational modifications of proteins: Cellular redox processes and murzyme-mediated metabolo-proteomics

Murburn concept constitutes the thesis that diffusible reactive species or DRS are obligatorily involved in routine metabolic and physiological activities. Murzymes are defined as biomolecules/proteins that generate/modulate/sustain/utilize DRS. Murburn posttranslational modifications (PTMs) result because murburn/murzyme functionalism is integral to cellular existence. Cells must incorporate the inherently stochastic nature of operations mediated by DRS. Due to the earlier/inertial stigmatic perception that DRS are mere agents of chaos, several such outcomes were either understood as deterministic modulations sponsored by house-keeping enzymes or deemed as unregulated nonenzymatic events resulting out of “oxidative stress”. In the current review, I dispel the myths around DRS-functions, and undertake systematic parsing and analyses of murburn modifications of proteins. Although it is impossible to demarcate all PTMs into the classical or murburn modalities, telltale signs of the latter are evident from the relative inaccessibility of the locus, non-specificities and mechanistic details. It is pointed out that while many murburn PTMs may be harmless, some others could have deleterious or beneficial physiological implications. Some details of reversible/irreversible modifications of amino acid residues and cofactors that may be subjected to phosphorylation, halogenation, glycosylation, alkylation/acetylation, hydroxylation/oxidation, etc. are listed, along with citations of select proteins where such modifications have been reported. The contexts of these modifications and their significance in (patho)physiology/aging and therapy are also presented. With more balanced explorations and statistically verified data, a definitive understanding of normal versus pathological contexts of murburn modifications would be obtainable in the future.     

Impact of different pH control agents on biopesticidal activity of<Emphasis Type="Italic"> Bacillus thuringiensis</Emphasis> during the fermentation of starch industry wastewater

Different pH control agents (NaOH/H₂SO₄—SodSulp, NaOH/CH₃COOH—SodAcet, NH₄OH/CH₃COOH—AmmoAcet and NH₄OH/H₂SO₄—AmmoSulp) were used to investigate their effects on growth, enzyme production (alkaline protease and amylase), and entomotoxicity of Bacillus thuringiensis var. kurstaki HD-1 (Btk) against eastern spruce budworm larvae (Choristoneura fumiferana) using starch industry wastewater (SIW) as a raw material in a 15-l fermentor. AmmoSulp and SodSulp were found to be the best pH control agents for alkaline protease and amylase production, respectively; whereas, the fermented broth obtained by using SodAcet as pH control agents recorded the highest delta-endotoxin production of 1043.0 mg/l and entomotoxicity value 18.4 × 10⁹ SBU/l. Entomotoxicity of re-suspended centrifuged pellet in one-tenth of original volume in case of SodAcet as pH control agents was 26.7 × 10⁹ SBU/l and was the highest value compared to three other pH control agents.     

Attempted Transformation of Wheat (Triticum aestivum) and Tobacco (Nicotiana tabacum) by Plasmid DNA Uptake Via the Pollen-tube Pathway

Plasmid DNA (CaMVGUS, containing β-glucuronldase gene) was used to transform developing seed of wheat and tobacco through pollen-tube pathway. The DNA was applied on the ovule end of excised styles and stigmas of wheat and tobacco after pollination. None of the 272 wheat and 13,567 tobacco plants obtained after application of the isolated DNA showed β-glucuronidase activity suggesting that the pollen-tube pathway may not be effective for transformation of plants.     

Sodium-independent low-affinity D-glucose transport by human sodium/D-glucose cotransporter 1: critical role of tryptophan 561

Although there is no evidence of significant Na-independent glucose flux in tissues naturally expressing SGLT1, previous kinetic and biophysical studies suggest that sodium/d-glucose cotransporter 1 (hSGLT1) can facilitate sodium-independent d-glucose transport and may contain more than one sugar binding site. In this work, we analyze the kinetic properties and conformational states of isolated hSGLT1 reconstituted in liposomes by transport and fluorescence studies in the absence of sodium. In the transport studies with hSGLT1, significant sodium-independent phlorizin inhibitable alpha-methyl d-glucopyranoside (alpha-MDG) uptake was observed which amounted to approximately 20% of the uptake observed in the presence of a sodium gradient. The apparent affinity constant for alpha-MDG was thereby 3.4 +/- 0.5 mM, a value approximately 10-fold higher than that in the presence of sodium. In the absence of sodium, various sugars significantly decreased the intrinsic Trp fluorescence of hSGLT1 in proteoliposomes exhibiting the following sequence of affinities: alpha-MDG > d-glucose approximately d-galactose > 6-deoxy-d-glucose > 2-deoxy-d-glucose > d-allose. Furthermore, significant protection effects of d-glucose or phlorizin against potassium iodide, acrylamide, or trichloroethanol quenching were observed. To locate the Trps involved in this reaction, we generated mutants in which all Trps were sequentially substituted with Phe. None of the replacements significantly affected sodium-dependent uptake. Uptake in the absence of sodium and typical fluorescence changes depended, however, on the presence of Trp at position 561. This Trp residue is conserved in all known SGLT1 forms (except Vibrio parahaemolyticus SGLT) and all SGLT isoforms in humans (except hSGLT3). If all these data are taken into consideration, it seems that Trp-561 in hSGLT1 forms part of a low-affinity sodium-independent binding and/or translocation site for d-glucose. The rate of sodium-independent translocation via hSGLT1 seems, however, to be tightly regulated in the intact cell by yet unknown factors.     

Multifarious plant growth promoting characteristics of chickpea rhizosphere associated Bacilli help to suppress soil-borne pathogens

Wilt and root rot are the major constraints in chickpea production and very difficult to manage through agrochemicals. Hence, for an ecofriendly and biological management, 240 strains of Bacillus and Bacillus derived genera were isolated from chickpea rhizosphere, further narrowed down to 14 strains on the basis of in vitro production of indole acetic acid, siderophore, phosphate solubilization, hydrolytic enzymes and were evaluated for antagonism against chickpea pathogens (Fusarium oxysporum f. sp. ciceri race 1, F. solani and Macrophomina phaseolina). The strains were identified on the basis of physiological characters and 16S RNA gene sequencing. The genotypic comparisons of strains were determined by BOX-polymerase chain reaction profiles and amplified rDNA restriction analysis. These isolates were evaluated in greenhouse assay in which B. subtilis (B-CM191, B-CV235, B-CL-122) proved to be effective in reducing wilt incidence and significant enhancement in growth (root and shoot length) and dry matter of chickpea plants. PCR amplification of bacillomycin (bmyB) and β-glucanase genes suggests that amplified genes from the Bacillus could have a role to further define the diversity, ecology, and biocontrol activities in the suppression of soil-borne pathogens.