Interaction between coat protein and replication initiation protein of Mung bean yellow mosaic India virus might lead to control of viral DNA replication

In addition to their encapsidation function, viral coat proteins (CP) contribute to viral life cycle in many different ways. The CPs of the geminiviruses are responsible for intra- as well as inter-plant virus transmission and might determine the yield of viral DNA inside the infected tissues by either packaging the viral DNA or interfering with the viral replicative machinery. Since the cognate Rep largely controls the rolling circle replication of geminiviral DNA, the interaction between Rep and CP might be worthwhile to examine for elucidation of CP-mediated control of the viral DNA copy number. Here a reasonably strong interaction between Rep and CP of the geminivirus Mung bean yellow mosaic India virus is reported. The domain of interaction has been mapped to a central region of Rep. The replication initiation activity of Rep, i.e., its nicking and closing function, is down regulated by CP. This report highlights how CP could be important in controlling geminiviral DNA replication

Distinct evolutionary histories of the DNA-A and DNA-B components of bipartite begomoviruses

<p>Abstract</p> <p>Background</p> <p>Viruses of the genus <it>Begomovirus </it>(family <it>Geminiviridae</it>) have genomes consisting of either one or two genomic components. The component of bipartite begomoviruses known as DNA-A is homologous to the genomes of all geminiviruses and encodes proteins required for replication, control of gene expression, overcoming host defenses, encapsidation and insect transmission. The second component, referred to as DNA-B, encodes two proteins with functions in intra- and intercellular movement in host plants. The origin of the DNA-B component remains unclear. The study described here was initiated to investigate the relationship between the DNA-A and DNA-B components of bipartite begomoviruses with a view to unraveling their evolutionary histories and providing information on the possible origin of the DNA-B component.</p> <p>Results</p> <p>Comparative phylogenetic and exhaustive pairwise sequence comparison of all DNA-A and DNA-B components of begomoviruses demonstrates that the two molecules have very distinct molecular evolutionary histories and likely are under very different evolutionary pressures. The analysis highlights that component exchange has played a far greater role in diversification of begomoviruses than previously suspected, although there are distinct differences in the apparent ability of different groups of viruses to utilize this "sexual" mechanism of genetic exchange. Additionally we explore the hypothesis that DNA-B originated as a satellite that was captured by the monopartite progenitor of all extant bipartite begomoviruses and subsequently evolved to become the integral (essential) genome component that we recognize today. The situation with present-day satellites associated with begomoviruses provides some clues to the processes and selection pressures that may have led to the "domestication" of a wild progenitor of the DNA-B component.</p> <p>Conclusions</p> <p>The analysis has highlighted the greater genetic variation of DNA-B components, in comparison to the DNA-A components, and that component exchange is more widespread than previously demonstrated and confined to viruses from the Old World. Although the vast majority of New World and some Old World begomoviruses show near perfect co-evolution of the DNA-A and DNA-B components, this is not the case for the majority of Old World viruses. Genetic differences between Old and New World begomoviruses and the cultivation of exotic crops in the Old World are likely factors that have led to this dichotomy.</p

PCNA Interacts with Indian Mung Bean Yellow Mosaic Virus Rep and Downregulates Rep Activity

Proliferative cell nuclear antigen (PCNA), a conserved plant protein as well as an important replication factor, is induced in response to geminivirus infection in the resting cells of the phloem tissues. The biochemical role of PCNA in rolling circle replication (RCR) of geminivirus DNA has not been explored in detail. The initiation of RCR of the bipartite genome of a geminivirus, Indian mung bean yellow mosaic virus (IMYMV), is mainly controlled by viral protein Rep (or AL1 or AC1). The role of host PCNA in RCR of IMYMV was revealed by studying the physical and functional interactions between recombinant PCNA and recombinant IMYMV Rep. Pea nuclear PCNA as well as recombinant pea PCNA showed binding to recombinant Rep in experiments involving both affinity chromatography and yeast two-hybrid approaches. The contacting amino acid residues of PCNA seemed to be present throughout a wide region of the trimeric protein, while those of Rep appeared to be localized only in the middle part of the protein. The site-specific nicking-closing activity and the ATPase function of IMYMV Rep were impaired by PCNA. These observations lead to interesting speculations about the control of viral RCR and dynamic profiles of protein-protein interactions at the RCR origin of the geminiviruses

Functional Outcome of Acute Minimally Displaced Scaphoid Waist Fractures Treated with Percutaneous Headless Compression Screw Fixation: A Prospective Cohort Study

Introduction: Scaphoid fracture incidence has increased recently due to increased participation of people in sports and increased road traffic accidents and easy availability of diagnostic tools like Computed Tomography (CT), which help in easily diagnosing scaphoid fractures, and may be missed on routine radiographs. Aim: To evaluate the functional outcome of surgical intervention with percutaneous headless compression screw fixation for acute minimally displaced scaphoid fractures. Materials and Methods: The present study was a prospective cohort study in which patients with acute fractures of scaphoid bone managed with percutaneous headless compression screw fixation were included between January 2020 to December 2022 and were evaluated using the Modified Mayo Wrist Score (MMWS) and Disabilities of Arm, Shoulder and Hand (DASH) score. The data obtained was entered into a Microsoft Excel sheet, and statistical analysis was performed using a Statistical Package for the Social Sciences (SPSS) version 20.0. Results: The study included 55 patients with a mean age of 32.9 years, out of which 43 were males and 12 were females. Road traffic accident injuries were in 19 patients, 17 were sports injuries and 19 were due to direct trauma. All patients were managed by percutaneous headless compression screw fixation. Among these, 27 patients showed excellent outcomes, 24 showed good outcomes, and four showed fair outcomes. Conclusion: This study shows that percutaneous fixation of minimally displaced scaphoid fractures results in early symptomatic relief and functional recovery. It shows that percutaneous fixation using a headless compression screw has similar functional outcomes and less hospital stay and patient scarring than in open fixation methods. Functional recovery is faster with percutaneous fixation than in non operative and open fixation