Riboswitch regulation in cyanobacteria is independent of their habitat adaptations.

Cyanobacteria are one of the ancient bacterial species occupying a variety of habitats with diverse metabolic preferences. RNA regulators like riboswitches play significant role in controlling the gene expression in prokaryotes. The taxonomic distribution of riboswitches suggests that they might be one of the oldest mechanisms of gene control system. In this paper, we analyzed the distribution of different riboswitch families in various cyanobacterial genomes. It was observed that only four riboswitch classes were abundant in cyanobacteria, B12-element (Cob)/AdoCbl/AdoCbl-variant riboswitch being the most abundant. The analysis suggests that riboswitch mode of regulation is present in cyanobacterial species irrespective of their habitat types. A large number of unidentified genes regulated by riboswitches listed in this analysis indicate the wide range of targets for these riboswitch families. The analysis revealed a large number of genes regulated by riboswitches which may assist in elaborating the diversity among the cyanobacterial species.

Characterization, phytochemical profiling, antioxidant, and cytotoxicity of underutilized medicinal plants and composite flour.

In this investigation, three medicinal plant powders and a composite flour developed from them were analyzed. FESEM/EDS illustrated irregularly shaped particles in the plant powders except for Withania, which had round to oval shape particles. XRD analysis displayed a semi-crystalline nature of powders, except for Asparagus, which showed amorphous behavior. Both methanol and ethanol plant extracts exhibited significantly higher antioxidants, total phenols, and cell viability. Amongst, optimized composite flour (OCF) methanolic extract demonstrated the highest total phenolic content (69.2 ± 0.11 µg GAE/ml), potent cell viability against A549 cells (3.35 ± 0.15% at 50 µg/ml), and strong free-radical scavenging activity (48.89 ± 0.67 at 200 µg/ml). GCMS and FTIR analyses of the methanolic extracts demonstrated the presence of essential phytoconstituents and functional groups. In silico studies of the phytocomponents, ethyl isoallocholate, 3-Deoxy-d-mannoic lactone, and 4,5-Diamino-2-hydroxypyrimidine suggested good binding affinity against BAX, P53, and EGFR proteins with no toxicity and a good drug score.

Clustered metallothionein genes are co-regulated in rice and ectopic expression of OsMT1e-P confers multiple abiotic stress tolerance in tobacco via ROS scavenging.

BACKGROUND: Metallothioneins (MT) are low molecular weight, cysteine rich metal binding proteins, found across genera and species, but their function(s) in abiotic stress tolerance are not well documented. RESULTS: We have characterized a rice MT gene, OsMT1e-P, isolated from a subtractive library generated from a stressed salinity tolerant rice genotype, Pokkali. Bioinformatics analysis of the rice genome sequence revealed that this gene belongs to a multigenic family, which consists of 13 genes with 15 protein products. OsMT1e-P is located on chromosome XI, away from the majority of other type I genes that are clustered on chromosome XII. Various members of this MT gene cluster showed a tight co-regulation pattern under several abiotic stresses. Sequence analysis revealed the presence of conserved cysteine residues in OsMT1e-P protein. Salinity stress was found to regulate the transcript abundance of OsMT1e-P in a developmental and organ specific manner. Using transgenic approach, we found a positive correlation between ectopic expression of OsMT1e-P and stress tolerance. Our experiments further suggest ROS scavenging to be the possible mechanism for multiple stress tolerance conferred by OsMT1e-P. CONCLUSION: We present an overview of MTs, describing their gene structure, genome localization and expression patterns under salinity and development in rice. We have found that ectopic expression of OsMT1e-P enhances tolerance towards multiple abiotic stresses in transgenic tobacco and the resultant plants could survive and set viable seeds under saline conditions. Taken together, the experiments presented here have indicated that ectopic expression of OsMT1e-P protects against oxidative stress primarily through efficient scavenging of reactive oxygen species.

Leptomonas seymouri Co-infection in Cutaneous Leishmaniasis Cases Caused by Leishmania donovani From Himachal Pradesh, India.

Himachal Pradesh in India is a newer endemic state with co-existence of cutaneous and visceral leishmaniasis. The cutaneous leishmaniasis cases are on an increase in the region and reported to be unusually caused by Leishmania donovani with limited molecular validation. In order to molecularly characterize the causative parasite of the cutaneous disease, parasite specific Internal-Transcribed Spacer 1 (ITS1) PCR RFLP and sequence analysis was performed on skin lesional biopsies from cutaneous leishmaniasis patients. Interestingly, we found the presence of Leptomonas seymouri in 38.5% (22/57) of the patients along with L. donovani detected in all the samples. L. seymouri is a monoxenous insect trypanosomatid, generally incapable of infecting humans. In recent years, the parasite is also reported to co-infect humans with L. donovani in visceral and post kala-azar dermal leishmaniasis (PKDL) cases prevalent in northeastern India. The finding of L. seymouri-L. donovani co-infection in unusual cutaneous cases from Himachal Pradesh is the first ever to our knowledge and imply a newer disease paradigm. There is an urgent need to understand the biology of Leptomonas co-infection with L. donovani and its possible role in visceral and/or dermotropic disease outcome. Importantly, L. seymouri co-infection in cutaneous cases and previously reported visceral and PKDL cases needs to be recognized as a newer phenomenon by the leishmaniasis surveillance program in India.

Putative osmosensor--OsHK3b--a histidine kinase protein from rice shows high structural conservation with its ortholog AtHK1 from Arabidopsis.

Prokaryotes and eukaryotes respond to various environmental stimuli using the two-component system (TCS). Essentially, it consists of membrane-bound histidine kinase (HK) which senses the stimuli and further transfers the signal to the response regulator, which in turn, regulates expression of various target genes. Recently, sequence-based genome wide analysis has been carried out in Arabidopsis and rice to identify all the putative members of TCS family. One of the members of this family i.e. AtHK1, (a putative osmosensor, hybrid-type sensory histidine kinase) is known to interact with AtHPt1 (phosphotransfer proteins) in Arabidopsis. Based on predicted rice interactome network (PRIN), the ortholog of AtHK1 in rice, OsHK3b, was found to be interacting with OsHPt2. The analysis of amino acid sequence of AtHK1 showed the presence of transmitter domain (TD) and receiver domain (RD), while OsHK3b showed presence of three conserved domains namely CHASE (signaling domain), TD, and RD. In order to elaborate on structural details of functional domains of hybrid-type HK and phosphotransfer proteins in both these genera, we have modeled them using homology modeling approach. The structural motifs present in various functional domains of the orthologous proteins were found to be highly conserved. Binding analysis of the RD domain of these sensory proteins in Arabidopsis and rice revealed the role of various residues such as histidine in HPt protein which are essential for their interaction.

Sequence and structural characterization of Trx-Grx type of monothiol glutaredoxins from Ashbya gossypii.

Glutaredoxins are enzymatic antioxidants which are small, ubiquitous, glutathione dependent and essentially classified under thioredoxin-fold superfamily. Glutaredoxins are classified into two types: dithiol and monothiol. Monothiol glutaredoxins which carry the signature "CGFS" as a redox active motif is known for its role in oxidative stress, inside the cell. In the present analysis, the 138 amino acid long monothiol glutaredoxin, AgGRX1 from Ashbya gossypii was identified and has been used for the analysis. The multiple sequence alignment of the AgGRX1 protein sequence revealed the characteristic motif of typical monothiol glutaredoxin as observed in various other organisms. The proposed structure of the AgGRX1 protein was used to analyze signature folds related to the thioredoxin superfamily. Further, the study highlighted the structural features pertaining to the complex mechanism of glutathione docking and interacting residues.

Comparative structural modeling of a monothiol GRX from chickpea: insight in iron-sulfur cluster assembly.

Glutaredoxins (GRXs) are small, ubiquitous, multifunctional, heat-stable and glutathione-dependent thiol-disulphide oxidoreductases, classified under thioredoxin-fold superfamily. In the green lineage, GRXs constitute a complex family of proteins. Based on their active site, GRXs are classified into two subfamilies: dithiol and monothiol. Monothiol GRXs contain 'CGFS' as a redox active motif and assist in maintaining redox state and iron homeostasis within the cell. Using RACE strategy, a full length cDNA of chickpea (Cicer arietinum) glutaredoxin 3 (CarGRX3) was cloned and sequenced. The cDNA contains open reading frame of 537 bp encoding 178 amino acids and exhibits features of other known 'CGFS' type GRXs. Based on the multiple sequence alignment among CarGRX3 and monothiol GRXs of other photosynthetic organisms, the characteristic motif (KGX4PXCGFSX([29/30/32])KX4WPTXPQX4GX3GGXDI) with 18 invariant residues was observed. The proposed structure of CarGRX3 was compared with structurally resolved monothiol GRXs of other organisms. The CarGRX3 and nearest Arabidopsis homolog (AtGRXcp) shares 76% sequence identity which was reflected by their 3D-structure conservation. The structure of chickpea monothiol GRX (CarGRX3) coordinates glutathione ligated [2Fe-2S] cluster in a homodimeric form, highlighting the structural basis for iron-sulfur cluster (ISC) assembly and delivery to acceptor proteins. The present study on CarGRX3 model highlighted the utility of the theoretical approaches to understand complex biological phenomena such as glutathione docking and incorporation of GSH-ligated [2Fe-2S] cluster.