Pathway · 5 proteins
Bacterial secretion system
Proteins of this group that KEGG places on its “Bacterial secretion system” map for Aquifex aeolicus.
How it works
This map covers the large machines bacteria use to move proteins across the whole envelope. The Aquifex proteins here belong to the type II secretion and type IV pilus family: an outer-membrane channel (secretin), an ATP-driven motor and pilin-like parts. What this machine carries in Aquifex is not known.
Grouped by KEGG pathway map. The explanation above is the atlas’s own; the map itself covers more organisms than Aquifex.
Its proteins
| Protein | EC | Reaction (UniProt) | Metal or cluster | Amino acids | Certainty |
|---|---|---|---|---|---|
| SAM-like helix-hairpin-helix tandem domain-containing protein | — | — | — | 281 | Unspecified |
| General secretion pathway protein D | — | — | — | 625 | Unspecified |
| PDZ domain-containing protein | — | — | — | 262 | Unspecified |
| General secretion pathway protein E | — | — | — | 469 | Unspecified |
| Type II secretion system core protein G | — | — | — | 133 | Unspecified |
Also part of this pathway
These proteins are described under another pathway, but also take part here.
| Protein | EC | Reaction (UniProt) | Metal or cluster | Amino acids | Certainty |
|---|---|---|---|---|---|
| Protein translocase subunit SecYHome: Protein translocation | — | — | — | 429 | Step named |
| Protein-export membrane protein SecGHome: Protein translocation | — | — | — | 100 | Step named |
| Sec translocon accessory complex subunit YajCHome: Protein translocation | — | — | — | 102 | Step named |
| Sec-independent protein translocase protein TatCHome: Protein translocation | — | — | — | 240 | Step named |
| Protein translocase subunit SecFHome: Protein translocation | — | — | — | 288 | Step named |
| Signal recognition particle proteinHome: Protein targeting | 3.6.5.4 | GTP + H2O = GDP + phosphate + H(+) | — | 454 | Step named |
| Membrane protein insertase YidCHome: Protein export | — | — | — | 502 | Step named |
| Protein translocase subunit SecAHome: Protein translocation | 7.4.2.8 | ATP + H2O + cellular proteinSide 1 = ADP + phosphate + cellular proteinSide 2. | — | 984 | Step named |
| Signal recognition particle receptor FtsYHome: Protein targeting | 3.6.5.4 | GTP + H2O = GDP + phosphate + H(+) | — | 461 | Step named |
| Protein translocase subunit SecDHome: Protein translocation | — | — | — | 501 | Step named |
Origins
How could large protein machines that span the envelope have arisen?
None of the books searched gives a prebiotic route to a secretion system.
Rana argues that the type III secretion system, a related machine that injects proteins into other cells, is irreducibly complex and closely resembles human-made devices. The secretion proteins in Aquifex belong to the related type II and pilus family: an outer-membrane gate, an ATP-driven motor and a piston must all be present for the machine to work.
From the books: Rana, The Cell's Design.
The wider question for this part of the cell: origins for conserved, but we cannot say what they do.
Sources
- KEGG map aae03070 (enzymes of this organism highlighted)
Other pathways in this group: tRNA charging · Nutrient and metabolic state · Biosynthesis of various nucleotide sugars · Purine metabolism · Glyoxylate and dicarboxylate metabolism · Starch and sucrose metabolism · Homologous recombination · Fructose and mannose metabolism · Streptomycin biosynthesis · Other carbon fixation pathways · Nicotinate and nicotinamide metabolism · Not yet placed in a pathway