IGEM:IMPERIAL/2008/Projects/B. Subtilis Chassis

=Chassis=

To B.subtilis or not to B.subtilis, that is THE question

The publishing of the B.subtilis genome #1 may allow simple ways to obtain sequence for potentially useful promoters for the B.subtilis chassis

Vector
E.coli plasmids cannot replicate in B.subtilis and so regular biobricks are not usable in such a chassis.

In labs, constructs called shuttle primers capable of replicating in both species are used and often created by merging together an E.coli vector and a B.subtilis vector. One such B.subtilis vector is pC194 #2.

pC194 requires a DNA sequence approxiamtely 1300bp #3 in length that could be potentially cloned into the regular biobrick vector

Given the activity of B.subtilis degrading E.coli derived plasmids however. It may be possible to utilise PCR for plasmid production and selection of transformants in B.subtilis to by-pass this issue, or to produce the plasmid in B.subtilis which would be more difficult.

Thonly other option would be to use the Cambridge 2007 approach and attempt to produce a modified shuttle vector to BioBrick standard

Promoters
Constitutive promoters:

Use of basal transcription promoters, potentially the promoter for one or various rRNAs, P3 promoter #4, RNAP subunit gene promoters and metablic gene promoters.

| Annotated B.subtilis genome

| Metabolic Pathways of B.subtilis

Probably ideal to pick a few (say 5) and characterise in order to find relative levels for use
 * 1 rRNA promoter
 * 1+ Metabolic related promoter (potential inducibility)
 * 1 RNAP subunit promoter
 * P3 promoter
 * Another basaly transcribe sequence

All non-constiutive promoters should remain functional in B.subtilis though leaky (basal) transcription rate will however be different, the key promoter is the one at the start of the chain...

RBS
On a preliminary basis, there appears to be some issues realted to the B.subtilis RBS, particularly the sequence and also codon usage with the normal AUG becoming UUG in B.subtilis #5

This will need looking into if B.subtilis is to be used

Reference

 * 1) 1 pmid=9384377
 * 2) 2 pmid=6950931
 * 3) 3 pmid=6323171
 * 4) 4 pmid=17158663
 * 5) 5 pmid=6793593