If even one of these 39 complex protein machines is missing or defective, cell division (reproduction) of the bacteria is impossible.
Question: How was the first imaginary cell able to develop all these protein machines during its short life?
Bacterial binary fission is a complex and highly coordinated process that involves at least 39 various protein machines and assistant proteins. Below is a comprehensive list of the necessary proteins categorized based on their roles in the different stages of bacterial cell replication:
1. Initiation of Chromosome Replication
- DnaA: Initiator protein that binds to the origin of replication (oriC) and unwinds DNA.
- DnaB (Helicase): Unwinds the DNA double helix.
- DnaC: Helicase loader protein that assists DnaB.
- DnaG (Primase): Synthesizes RNA primers necessary for DNA polymerase to start DNA synthesis.
2. DNA Replication Machinery (Replisome)
- DNA Polymerase III Holoenzyme: The main enzyme complex responsible for DNA synthesis.
- α (alpha) subunit: Polymerase activity.
- ε (epsilon) subunit: Proofreading activity.
- θ (theta) subunit: Stabilizes the ε subunit.
- β (beta) clamp: Sliding clamp that holds DNA polymerase III onto the DNA.
- Clamp loader complex: Loads the β clamp onto the DNA.
- Single-Strand Binding Proteins (SSB): Stabilize single-stranded DNA.
- DNA Gyrase (Topoisomerase II): Relieves supercoiling ahead of the replication fork
- DNA Topoisomerase IV: Decatenates interlinked daughter chromosomes.
- DNA Polymerase I: Replaces RNA primers with DNA.
- DNA Ligase: Seals nicks in the DNA backbone, joining Okazaki fragments on the lagging strand.
4. Termination of Replication
- Tus Protein: Binds to ter (termination) sites on the chromosome to halt the replication fork.
5. Chromosome Segregation
- MukBEF Complex: Condenses and organizes the chromosome.
- ParAB System: Segregates chromosomes into daughter cells.
- FtsK: DNA translocase involved in chromosome segregation and cell division coordination.
6. Division Site Selection
- MinCDE System: Ensures the division septum forms at the cell center.
- MinC: Inhibits FtsZ polymerization.
- MinD: ATPase that recruits MinC to the membrane.
- MinE: Regulates MinD activity and localization.
7. Septum Formation (Z-ring Assembly)
- FtsZ: Tubulin-like protein that forms the Z-ring at the future division site.
- FtsA: Actin-like protein that connects FtsZ to the membrane.
- ZipA: Anchors FtsZ to the cytoplasmic membrane.
- ZapA, ZapB, ZapC, ZapD: Accessory proteins that stabilize the Z-ring.
8. Constriction and Cell Division
- FtsK: DNA translocase involved in coordinating septation with chromosome segregation.
- NOTE: This is a very complex protein machine. It has 1329 amino acids.
- FtsQ: Scaffold protein that recruits other division proteins.
- FtsL, FtsB: Part of the divisome complex, involved in stabilizing the constriction machinery.
- FtsW: Lipid II flippase involved in peptidoglycan synthesis.
- FtsI (PBP3): Penicillin-binding protein involved in septal peptidoglycan synthesis.
- FtsN: Activates peptidoglycan synthesis and finalizes septum formation.
9. Cell Wall Synthesis and Remodeling
- Penicillin-Binding Proteins (PBPs): Involved in peptidoglycan synthesis and remodeling.
- Autolysins: Enzymes that remodel peptidoglycan to allow cell separation.
10. Membrane Remodeling
- Amidases: Enzymes that separate daughter cells by hydrolyzing peptidoglycan cross-links.
- Phospholipid Synthases and Transferases: Involved in membrane synthesis and remodeling.
This categorization highlights the key proteins involved in bacterial binary fission and their roles in different stages of the process. The absence or malfunction of any of these proteins can significantly impair or prevent successful bacterial cell division. Every protein needs an extremely accurate design with atomic precision as scientists have noted. Conclusions: It is impossible for the complex protein machines necessary for cell division to have evolved step by step because cell division cannot succeed until all the necessary protein machines are precisely in place and functional. No naturally occurring protocells have been observed in the wild. Evolution never happened.
