Non-metabolic role of alpha-enolase in virus replication.

Viruses are extremely complex and highly evolving microorganisms; thus, it is difficult to analyse them in detail. The virion is believed to contain all the essential components required from its entry to the establishment of a successful infection in a susceptible host cell. Hence, the virion composition is the principal source for its transmissibility and immunogenicity. A virus is completely dependent on a host cell for its replication and progeny production. Occasionally, they recruit and package host proteins into mature virion. These incorporated host proteins are believed to play crucial roles in the subsequent infection, although the significance and the molecular mechanism regulated are poorly understood. One such host protein which is hijacked by several viruses is the glycolytic enzyme, Enolase (Eno-1) and is also packaged into mature virion of several viruses. This enzyme exhibits a highly flexible nature of functions, ranging from metabolic to several non-metabolic activities. All the glycolytic enzymes are known to be moonlighting proteins including enolase. The non-metabolic functions of this moonlighting protein are also highly diverse with respect to its cellular localization. Although very little is known about the virological significance of this enzyme, several of its non-metabolic functions have been observed to influence the virus replication cycle in infected cells. In this review, we have attempted to provide a comprehensive picture of the non-metabolic role of Eno-1, its significance in the virus replication cycle and to stimulate interest around its scope as a therapeutic target for treating viral pathologies.

Interaction of potyvirus helper component-proteinase (HcPro) with RuBisCO and nucleosome in viral infections of plants.

Bean common mosaic virus (BCMV) causes severe disease in Phaseolus vulgaris plants. One of its non structural protein, the helper-component proteinase (HcPro) involves in multiple roles in aphid transmission, RNA binding, suppression of gene silencing and protease activity. The multifunctional role of HcPro hint towards its regulation at multiple host cellular sites. The mechanisms of these regulatory activities are poorly understood. Therefore, it is very important to study the molecular level interaction of HcPro with different cellular components. In this study, we demonstrate that the HcPro interacts with RuBisCo, an enzyme of chloroplast origin which might plays a crucial role in virus infection. A further line of experiments were carried out with factors of nuclear origin. Due to nucleic acid binding activity of HcPro, it showed interaction with dsDNA of nucleosome, as ascertained through electrophoretic mobility shift assay (EMSA). Interestingly, HcPro interacts with host nucleoprotein histones, H3 and H4. The gel-overlay assay and native electrophoresis-western blot analysis (NEWeB) revealed a direct interaction of BCMV HcPro with host nucleosome and with histones. These findings suggest that the BCMV through HcPro, not only utilize the host cytoplasmic components but also use host nuclear factors for its propagation and disease development.

Elucidating the functional aspects of different domains of bean common mosaic virus coat protein.

The coat protein (CP) is the only structural protein present in the polyprotein of bean common mosaic virus. The well known characteristics of the CP are self-oligomerization and nucleic acid binding activity. The studies of the coat protein mutants revealed that the oligomeric property of CP solely depends on the amino-terminal residues and the nucleic acid binding domain present at the 194-202 residue position. The 3'UTR RNA of the virus showed high binding affinity with the RNA binding domain as compared to the 5'UTR RNA. Further, the intrinsic fluorescence study of the CP also suggested that the N- and C-terminal of CP contains a highly disordered region. The present study also illustrates that the coat protein contains a conserved RNA binding pocket among the potyviruses, but displays divergent oligomerization propensities due to the difference in residue at the N- and C-terminal.

Convergent evolution in bacteria from multiple origins under antibiotic and heavy metal stress, and endophytic conditions of host plant.

The focus of this work is to study the convergent evolution in bacteria from multiple origins under antibiotic and heavy metal stress, and endophytic conditions of host plant cultivated on the Yamuna river bank. Forty-one endophytic bacteria (EB) were isolated from green leafy vegetables (GLV's) and were found to be resistant to a wide range of antibiotics (AB) and heavy metals (HM) tested. Further, they showed susceptibility to Quinolones group of antibiotics, and the HM, Cadmium, Chromium, and Mercury. Twenty-seven percent of these bacteria endowed with Class I integron. The probability of co-existence of HM resistance with ß­lactams was higher, whereas quinolones group of AB recorded lesser values. These EB owned a wide array of beneficial traits, through which they improved the plant health under HM and salt stress conditions. Bacterial identity revealed the association of both plant beneficial and human pathogenic bacteria as an endophyte with GLV's. Principal component analysis showed a pattern of convergent evolution irrespective of their origin. In conclusion, under the selection pressure of AB and HM, the susceptible EB population may reduce with time and the resistant native/introduced bacteria might survive. The vertical and horizontal gene transfer between introduced and native bacteria is the crucial factor in enhancing their fitness along with the host plant to survive under abiotic stress conditions.

Inhibition of TMV multiplication by siRNA constructs against TOM1 and TOM3 genes of Capsicum annuum.

The host proteins TOM1 and TOM3 associated with tonoplast membrane are shown to be required for efficient multiplication of Tobamoviruses. In this study, homologous of TOM1 and TOM3 genes were identified in pepper (Capsicum annuum) using specific primers. Their gene sequences have similarity to Nicotiana tabacum NtTOM1 and NtTOM3. Sequence alignment showed that CaTOM1 and CaTOM3 are closely related to TOM1 and TOM3 of N. tabacum and Solanum lycopersicum with 90% and 70% nucleotide sequence identities, respectively. RNA interference approach was used to suppress the TOM1 and TOM3 gene expression which in turn prevented Tobacco mosaic virus replication in tobacco. Nicotiana plants agro-infiltrated with siRNA constructs of TOM1 or TOM3 showed no mosaic or necrotic infection symptoms upon inoculation with TMV. The results indicated that silencing of TOM1 and TOM3 of pepper using the siRNA constructs is an efficient method for generating TMV-resistant plants.