Chapter 8-2. Central Dogma of Microbiology
Recommended Article: 【Biology】 Chapter 8. Central Dogma
1. Transcription Regulation
⑴ Method 1. DNA binding proteins
① Interactions between proteins and nucleic acids
○ Non-specific interactions: Common in eukaryotic cells and archaea.
○ Specific interactions
② Structure 1. Helix-turn-helix motif
○ Recognition Helix: Interacts specifically with DNA.
○ Turn: Composed of three amino acids, the first typically being glycine.
○ Stabilizing helix: Stabilizes the recognition helix through hydrophobic interactions with the recognition helix.
③ Structure 2. Zinc finger
○ Frequently found in eukaryotic regulatory proteins.
○ Binds to zinc (Zn) ions.
○ Recognition helix: Part of an alpha-helix. Binds to the DNA major groove.
○ DNA-binding proteins contain at least two zinc fingers.
④ Structure 3. Leucine zipper
○ Contains a region where a leucine residue appears every seven amino acids.
○ Does not bind to DNA directly but binds to two recognition helices, influencing DNA orientation.
⑤ Structure 4. Helix-loop-helix motif
⑥ Example 1. Inducers and corepressors
⑦ Example 2. Lactose operon
⑧ Example 3. Maltose metabolism in E. coli: Regulated by a regulon.
⑨ Example 4. The NrpR protein synthesized by Methanococcus maripaludis (methanogen) during nitrogen fixation is transcriptionally regulated.
⑩ Example 5. Pyrococcus furiosus (hyperthermophile) lacks a glucose transporter but carries out glycolysis, involving TrmBL1, which functions as both a repressor and activator.
⑵ Method 2. sRNA (Small RNA): 40 ~ 400 nucleotides
⑶ Method 3. Riboswitch
⑷ Method 4. Attenuation
① Example 1. Tryptophan Operon
2. Signal Transduction
⑴ Method 1. Two-component regulatory system: E. coli has approximately 50 two-component regulatory systems.
Table 1. Two-component regulatory systems in E. coli
① Example 1. Osmoregulation in E. coli: Involves OmpC, OmpF, OmpR, and EnvZ.
② Example 2. Chemotaxis: Involves MCP, CheA, CheW, CheY, and CheB.
③ Example 3. Regulation of flagellin rotation: Involves CheY and CheP.
④ Example 4. Quorum sensing: Detection of neighboring cell density
⑤ Example 5. Toxicity of Shiga toxin-producing E. coli: Involves AI-3.
⑥ Example 6. Toxicity of Staphylococcus aureus: Involves ArgA, ArgB, ArgC, and ArgD.
⑦ Example 7. Nutrient deprivation response in E. coli: Increased production of ppGpp inhibits cell division.
⑧ Example 8. Nutrient deprivation response in C. crescentus: Increased ppGpp production enhances motility.
⑨ Example 9. Response of M. tuberculosis to host immune reactions: Increased ppGpp production enhances persister cell formation.
⑩ Example 10. Global network
Table 2. Global network
⑪ Example 11. Two-component regulatory system in Streptomyces: Involves PhoR (membrane-bound histidine kinase sensor protein) and PhoP (cytoplasmic transcriptional regulator).
⑫ Example 12. Heat stress response in E. coli: Involves DnaK (≒ Hsp70), GroEL (≒ Hsp60), GroES (≒ Hsp10), and RpoH (σ32).
3. Metabolic Regulation
⑴ Method 1. Feedback inhibition
⑵ Method 2. Post-translational regulation
① Example 1. PPII signal transduction: Involves PII and GlnD.
② Example 2. Inactivation of sigma factors: Involves RpoE and RseA.
Input: 2022.07.12 23:06