Browsing by Author "Pasrija, Richa"

Now showing 1 - 3 of 3

Analysis of differential expression of mediator subunit genes in Arabidopsis
(Landes Bioscience, 2012) Pasrija, Richa; Thakur, Jitendra K.
Mediator is a conserved eukaryotic multiprotein complex required by RNA polymerase II for transcription of its target genes. Till date, there is no report explaining the signals that affect the overall concentration of individual Med subunits. In this report, we have analyzed the effect of different phytohormones and stresses on the transcript level of Med genes in Arabidopsis. Hormones like auxin and JA, and cold stress did not show significant effect. ABA moderately increased the transcript abundance of more than 70% of AtMed genes analyzed in this study. However, there was noticeable change in the transcript level of several AtMed genes in response to BR. Stresses like high light, dark and salt also caused significant change in the transcript abundance of many AtMed genes. These data reveal that different environmental cues can affect stoichiometric concentration of Med subunits by affecting the transcription of their respective genes. This may, in turn, affect the overall arrangement of functional Mediator complex. This also suggests that some subunits may have some specific functions to play in response different signals.
Sequence and expression analyses of KIX domain proteins suggest their importance in seed development and determination of seed size in rice, and genome stability in Arabidopsis
(Springer, 2013) Thakur, Jitendra K.; Agarwal, Pinky; Parida, Swarup K.; Bajaj, Deepak; Pasrija, Richa
The KIX domain, which mediates protein-protein interactions, was first discovered as a motif in the large multidomain transcriptional activator histone acetyltransferase p300/CBP. Later, the domain was also found in Mediator subunit MED15, where it interacts with many transcription factors. In both proteins, the KIX domain is a target of activation domains of diverse transcription activators. It was found to be an essential component of several specific gene-activation pathways in fungi and metazoans. Not much is known about KIX domain proteins in plants. This study aims to characterize all the KIX domain proteins encoded by the genomes of Arabidopsis and rice. All identified KIX domain proteins are presented, together with their chromosomal locations, phylogenetic analysis, expression and SNP analyses. KIX domains were found not only in p300/CBP- and MED15-like plant proteins, but also in F-box proteins in rice and DNA helicase in Arabidopsis, suggesting roles of KIX domains in ubiquitin-mediated proteasomal degradation and genome stability. Expression analysis revealed overlapping expression of OsKIX_3, OsKIX_5 and OsKIX_7 in different stages of rice seeds development. Moreover, an association analysis of 136 in silico mined SNP loci in 23 different rice genotypes with grain-length information identified three non-synonymous SNP loci in these three rice genes showing strong association with long- and short-grain differentiation. Interestingly, these SNPs were located within KIX domain encoding sequences. Overall, this study lays a foundation for functional analysis of KIX domain proteins in plants.
Tissue specific expression profile of mediator genes in Arabidopsis
(Landes Bioscience (Taylor & Francis Grp), 2013) Pasrija, Richa; Thakur, Jitendra K.
Mediator is a gigantic multiprotein complex required for transcription of almost all the protein coding genes. In this report, we have analyzed the transcript abundance of 31 Med genes in different tissues of Arabidopsis. Our analysis revealed the tissue specific differential expression profile of many Med subunit genes suggesting they might be contributing in the formation, maturation or function of that specific tissue. Moreover, we also found increase or decrease in the expression level of several Med subunits during the same duration of specific processes (for example flowering) indicating probable enrichment of a particular arrangement of selected subunits during that process. Thus, this study suggests that not only specific Med subunits have functional relevance in specific processes, but specific arrangements of Med subunits might also play significant role in some processes in Arabidopsis or other plants.