질문:
[한글로 다음 글을 바탕으로 설명해주세요] Regulation of gene expression (in plant)
Gene expression can be regulated at many different points
- chromatin conformation
- Affecting the ability of RNA polymerase to bind to the DNA
- Modification of acetylation of lysine residues on core histones
- Methylation of DNA (altering chromatin conformation) can block transcription
- gene transcription
• Promoter:
- cis-elements
- TATA box: RNA polymerase II, transcription initiation, core or minimal promoter elements
- Lack of a TATA box: housekeeping genes, constitutive expression gene
- CAAT box and GC box: enhance the activity of RNA polymerase
- Transcription factors (trans-acting factors): signal transduction, DNA-binding region,
transcription regulation domain
TF: Helix-turn-helix (HTH), Leucine zipper (bZIP), Zinc finger, Helix-loop-helix (HLH),
High-mobility group (HMG)-box motif
- nuclear RNA modification, splicing, turnover, and transport
• RNA modification: splicing
- Alternative splicing: different transcripts from the same gene
- Different transcripts in different tissues
- Different stimuli
- Multiple transcripts from a single gene
(Ex) - Rubisco activase: light-induced changes in the redox potential & changes in the ADP/ATP ratio
- FCA: RNA-binding protein promotes photoperiod-independent flowering in Arabidopsis 4 different transcripts (, , , and ) regulate the spatial & temporal accumulation of the functional FCA protein
- cytoplasmic RNA turnover
• Turnover:
- 5’ cap & 3’ poly(A) tail: stabilize RNA
- mRNA specific sequences or motifs: mRNA destabilization or increased transcripts
Ex. 1. DST (3’ UTR, downstream element) function:
Ex. 2. plant hormone auxin (SAUR transcripts): short-lived mRNAs
Ex. 3. light (Fed1 transcripts): increased transcripts
Ex. 4. sucrose (-amylase transcripts): destabilized transcripts
- Post-transcriptional process
Ex. 1. legumin mRNA (storage protein in seeds):
legumin mRNA levels (20-fold up), legumin transcripts levels (2-fold up)
during sulphur starvation condition
- translation
- 5’ cap & 3’ poly(A) tail: increase the efficiency of translation
- Distance of the AUG translation initiation codon from the 5’ end of the mRNA
- The secondary structure around the initiation codon
- The nucleotides in positions +4 to +11 are also involved in the regulation of gene expression
- post-translational modification
- Signal peptides: direct proteins to certain subcellular structures or organells
- Phosphorylation, glycosylation, or acetylation
- protein localization
- Signal peptides: direct proteins to certain subcellular structures or organells
- Phosphorylation, glycosylation, or acetylation
- protein turnover
• N-terminal amino acid: control to protein stability
- Met, Gly, Ser, Thr, and Val: stabilize proteins
- Arg, Asn, Asp, Gln, Glu, His, Ile, Leu, Lys, Phe, Trp, and Tyr: rapid degradation
• N-terminal amino acid by acetylation: increase the stability of the protein