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Importance of Mediator complex in the regulation and integration of diverse signaling pathways in plants.

Samanta S, Thakur JK - Front Plant Sci (2015)

Bottom Line: Basic transcriptional machinery in eukaryotes is assisted by a number of cofactors, which either increase or decrease the rate of transcription.Here, we have provided an overview of plant Mediator complex starting from its discovery to regulation of stoichiometry of its subunits.Wherever possible, attempts have been made to provide mechanistic insight of Mediator's involvement in these processes.

View Article: PubMed Central - PubMed

Affiliation: Plant Mediator Lab, National Institute of Plant Genome Research New Delhi, India.

ABSTRACT
Basic transcriptional machinery in eukaryotes is assisted by a number of cofactors, which either increase or decrease the rate of transcription. Mediator complex is one such cofactor, and recently has drawn a lot of interest because of its integrative power to converge different signaling pathways before channeling the transcription instructions to the RNA polymerase II machinery. Like yeast and metazoans, plants do possess the Mediator complex across the kingdom, and its isolation and subunit analyses have been reported from the model plant, Arabidopsis. Genetic, and molecular analyses have unraveled important regulatory roles of Mediator subunits at every stage of plant life cycle starting from flowering to embryo and organ development, to even size determination. It also contributes immensely to the survival of plants against different environmental vagaries by the timely activation of its resistance mechanisms. Here, we have provided an overview of plant Mediator complex starting from its discovery to regulation of stoichiometry of its subunits. We have also reviewed involvement of different Mediator subunits in different processes and pathways including defense response pathways evoked by diverse biotic cues. Wherever possible, attempts have been made to provide mechanistic insight of Mediator's involvement in these processes.

No MeSH data available.


Involvement of plant Mediator subunits in development, and various biotic and abiotic stress responses. Arrangement of Mediator subunits is modular in nature. Mediator complex subunits are arranged into four modules-Head module (Cyan), Middle module (Orange), Tail module (Green), and a separable Kinase module (Purple). Only the known and important functions of plant Mediator complex are shown in the figure. MED26 and plant-specific Mediator subunits (MED34, MED35, MED36, and MED37) are not shown in the figure because of insufficient information about their module positions.
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Figure 1: Involvement of plant Mediator subunits in development, and various biotic and abiotic stress responses. Arrangement of Mediator subunits is modular in nature. Mediator complex subunits are arranged into four modules-Head module (Cyan), Middle module (Orange), Tail module (Green), and a separable Kinase module (Purple). Only the known and important functions of plant Mediator complex are shown in the figure. MED26 and plant-specific Mediator subunits (MED34, MED35, MED36, and MED37) are not shown in the figure because of insufficient information about their module positions.

Mentions: The process of transcription in eukaryotic organism is an immensely complex and highly orchestrated phenomenon, and is mediated by a plethora of proteins wherein primary role is played by RNA polymerase II (RNAP II) (Lee and Young, 2000). The process is regulated both at the transcription initiation and elongation stages by a seemingly endless collections of regulatory proteins involved in different mechanisms (Woychik and Hampsey, 2002). Over the past 30 years, elegant biochemical, genetic, and structural biology works have established a core set of six general transcription factors (TFIIA, TFIIB, TFIID, TFIIE, TFIIF, and TFIIH) along with RNAP II as the core elements, which are obligatory to initiate and sustain any successful gene transcription event. On the other hand, among the numerous co-activators characterized till date to facilitate the initial recruitment of RNAP II to the core promoter and the subsequent transcript elongation, the Mediator complex has emerged as potentially the most crucial by virtue of its essentiality in RNAP II-mediated transcription (Myers and Kornberg, 2000; Conaway et al., 2005; Kornberg, 2005; Malik and Roeder, 2010). The Mediator complex is a highly conserved and integral part of RNAP II-mediated transcriptional machinery of the eukaryotes. In the past, the composition of the Mediator complex and the functions of different Mediator subunits have been reviewed several times focusing on yeasts and metazoans. In plant biology, the central role of Mediator complex in RNAP II-mediated transcriptional event has already been recognized by its discovery in Arabidopsis and other crop plants. The recent time has experienced a flush of interesting reports on the plant Mediator subunits detailing its quintessential role not only in growth and developmental processes, but also in biotic and abiotic stress responses (Figure 1). Realizing the need for an updated and critical analysis of roles of Mediator subunits in plants' life, this review summarizes the functions of Mediator subunits and provides insight about the depth and complexity of involvement of Mediator complex in transcriptional regulations of plant genes.


Importance of Mediator complex in the regulation and integration of diverse signaling pathways in plants.

Samanta S, Thakur JK - Front Plant Sci (2015)

Involvement of plant Mediator subunits in development, and various biotic and abiotic stress responses. Arrangement of Mediator subunits is modular in nature. Mediator complex subunits are arranged into four modules-Head module (Cyan), Middle module (Orange), Tail module (Green), and a separable Kinase module (Purple). Only the known and important functions of plant Mediator complex are shown in the figure. MED26 and plant-specific Mediator subunits (MED34, MED35, MED36, and MED37) are not shown in the figure because of insufficient information about their module positions.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4584954&req=5

Figure 1: Involvement of plant Mediator subunits in development, and various biotic and abiotic stress responses. Arrangement of Mediator subunits is modular in nature. Mediator complex subunits are arranged into four modules-Head module (Cyan), Middle module (Orange), Tail module (Green), and a separable Kinase module (Purple). Only the known and important functions of plant Mediator complex are shown in the figure. MED26 and plant-specific Mediator subunits (MED34, MED35, MED36, and MED37) are not shown in the figure because of insufficient information about their module positions.
Mentions: The process of transcription in eukaryotic organism is an immensely complex and highly orchestrated phenomenon, and is mediated by a plethora of proteins wherein primary role is played by RNA polymerase II (RNAP II) (Lee and Young, 2000). The process is regulated both at the transcription initiation and elongation stages by a seemingly endless collections of regulatory proteins involved in different mechanisms (Woychik and Hampsey, 2002). Over the past 30 years, elegant biochemical, genetic, and structural biology works have established a core set of six general transcription factors (TFIIA, TFIIB, TFIID, TFIIE, TFIIF, and TFIIH) along with RNAP II as the core elements, which are obligatory to initiate and sustain any successful gene transcription event. On the other hand, among the numerous co-activators characterized till date to facilitate the initial recruitment of RNAP II to the core promoter and the subsequent transcript elongation, the Mediator complex has emerged as potentially the most crucial by virtue of its essentiality in RNAP II-mediated transcription (Myers and Kornberg, 2000; Conaway et al., 2005; Kornberg, 2005; Malik and Roeder, 2010). The Mediator complex is a highly conserved and integral part of RNAP II-mediated transcriptional machinery of the eukaryotes. In the past, the composition of the Mediator complex and the functions of different Mediator subunits have been reviewed several times focusing on yeasts and metazoans. In plant biology, the central role of Mediator complex in RNAP II-mediated transcriptional event has already been recognized by its discovery in Arabidopsis and other crop plants. The recent time has experienced a flush of interesting reports on the plant Mediator subunits detailing its quintessential role not only in growth and developmental processes, but also in biotic and abiotic stress responses (Figure 1). Realizing the need for an updated and critical analysis of roles of Mediator subunits in plants' life, this review summarizes the functions of Mediator subunits and provides insight about the depth and complexity of involvement of Mediator complex in transcriptional regulations of plant genes.

Bottom Line: Basic transcriptional machinery in eukaryotes is assisted by a number of cofactors, which either increase or decrease the rate of transcription.Here, we have provided an overview of plant Mediator complex starting from its discovery to regulation of stoichiometry of its subunits.Wherever possible, attempts have been made to provide mechanistic insight of Mediator's involvement in these processes.

View Article: PubMed Central - PubMed

Affiliation: Plant Mediator Lab, National Institute of Plant Genome Research New Delhi, India.

ABSTRACT
Basic transcriptional machinery in eukaryotes is assisted by a number of cofactors, which either increase or decrease the rate of transcription. Mediator complex is one such cofactor, and recently has drawn a lot of interest because of its integrative power to converge different signaling pathways before channeling the transcription instructions to the RNA polymerase II machinery. Like yeast and metazoans, plants do possess the Mediator complex across the kingdom, and its isolation and subunit analyses have been reported from the model plant, Arabidopsis. Genetic, and molecular analyses have unraveled important regulatory roles of Mediator subunits at every stage of plant life cycle starting from flowering to embryo and organ development, to even size determination. It also contributes immensely to the survival of plants against different environmental vagaries by the timely activation of its resistance mechanisms. Here, we have provided an overview of plant Mediator complex starting from its discovery to regulation of stoichiometry of its subunits. We have also reviewed involvement of different Mediator subunits in different processes and pathways including defense response pathways evoked by diverse biotic cues. Wherever possible, attempts have been made to provide mechanistic insight of Mediator's involvement in these processes.

No MeSH data available.