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As sessile organisms, plants have evolved unique patterns of growth and development, elaborate metabolism and special perception and signaling mechanisms to environmental cues. Likewise, plants have complex and highly special programs for transcriptional control of gene expression. A case study for the special transcription control in plants is the expansion of general transcription factors, particularly the family of Transcription Factor IIB (TFIIB)-like factors with 15 members in Arabidopsis. For more than a decade, molecular and genetic analysis has revealed important functions of these TFIIB-like factors in specific biological processes including gametogenesis, pollen tube growth guidance, embryogenesis, endosperm development, and plant-microbe interactions. The redundant, specialized, and diversified roles of these TFIIB-like factors challenge the traditional definition of general transcription factors established in other eukaryotes. In this review, we discuss general transcription factors in plants with a focus on the expansion and functional analysis of plant TFIIB-like proteins to highlight unique aspects of plant transcription programs that can be highly valuable for understanding the molecular basis of plant growth, development and responses to stress conditions.
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Malectin/Malectin-like domain-containing proteins: a repertoire of cell surface molecules with broad functional potential.
Cell walls are at the front line of interactions between walled-organisms and their environment. They support cell expansion, ensure cell integrity and, for multicellular organisms such as plants, they provide cell adherence, support cell shape morphogenesis and mediate cell–cell communication. Wall-sensing, detecting perturbations in the wall and signaling the cell to respond accordingly, is crucial for growth and survival. In recent years, plant signaling research has suggested that a large family of receptor-like kinases (RLKs) could function as wall sensors partly because their extracellular domains show homology with malectin, a diglucose binding protein from the endoplasmic reticulum of animal cells. Studies of several malectin/malectin-like (M/ML) domain-containing RLKs (M/MLD-RLKs) from the model plant Arabidopsis thaliana have revealed an impressive array of biological roles, controlling growth, reproduction and stress responses, processes that in various ways rely on or affect the cell wall. Malectin homologous sequences are widespread across biological kingdoms, but plants have uniquely evolved a highly expanded family of proteins with ML domains embedded within various protein contexts. Here, we present an overview on proteins with malectin homologous sequences in different kingdoms, discuss the chromosomal organization of Arabidopsis M/MLD-RLKs and the phylogenetic relationship between these proteins from several model and crop species. We also discuss briefly the molecular networks that enable the diverse biological roles served by M/MLD-RLKs studied thus far.
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- Award ID(s):
- 1645858
- PAR ID:
- 10280350
- Date Published:
- Journal Name:
- The Cell surface
- Volume:
- 7
- ISSN:
- 2468-2330
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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SMAX1-LIKE (SMXL) proteins in plants are cellular signaling hubs, many of which are posttranslationally regulated by karrikins from smoke, the plant hormones strigolactones (SLs), and/or cues such as light and nutrients. SMXL proteins control diverse aspects of growth, development, and environmental adaptation in plants through transcriptional corepression and interactions with transcriptional regulator proteins. In flowering plants, the SMXL family comprises four phylogenetic clades with different roles. Functions of the aSMAX1 clade include control of germination and seedling development, while the SMXL78 clade controls shoot architecture. We investigated how SMXL roles are specified inArabidopsis thaliana.Through promoter-swapping experiments, we found thatSMXL7can partially replicateSMAX1function, butSMAX1cannot replaceSMXL7. This implies that the distinct roles of these genes are primarily due to differences in protein sequences rather than expression patterns. To determine which part of SMXL proteins specifies downstream control, we tested a series of protein chimeras and domain deletions of SMAX1 and SMXL7. We found an N-terminal region that is necessary and sufficient to specify control of germination, seedling growth, or axillary branching. We screened 158 transcription factors (TFs) for interactions with SMAX1 and SMXL7 in yeast two-hybrid assays. The N-terminal domain was necessary and/or sufficient for most of the 33 potential protein–protein interactions that were identified for SMAX1. This finding unlocks different ways to engineer plant growth control through cross-wiring SMXL regulatory “input” and developmental “output” domains from different clades and lays a foundation for understanding how functional differences evolved in the SMXL family.more » « less
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/http://doi.10.1016/j.tcsw.2021.100056
