Part:pSB2K3

From partsregistry.org

Inducible copy number BioBrick plasmid

pSB2K3 is a variable copy number plasmid carrying kanamycin resistance. The plasmid contains the F' replication origin and also the P1 lytic replication origin. Genes encoding proteins that are required to activate the P1 lytic replication origin are carried on the plasmid under the control of a lacI-regulated promoter. When grown in cells producing LacI the plasmid is maintained at very low copy (<10 per cell). When induced with IPTG the P1 lytic replication proteins are produced and the P1 lytic replication origin takes over, raising the copy number to very high levels (>100++ per cell). The copy control features of pSB2K3 are useful for cloning "difficult" parts while still being able to prepare large amounts of DNA.

Additionally, pSB2K3 has terminators bracketing its MCS ("multi-cloning site") which are designed to prevent transcription from *inside* the MCS from reading out into the vector. The efficiency of these terminators is known to be < 100%. Ideally we would construct a future set of terminators for bracketing a MCS that were 100% efficient in terminating both into and out of the MCS region.

Annotated APE file for pSB2K3

Plasmid map for pSB2K3

Usage and Biology

- - Copy number control & induction via IPTG ***

Cells that contain a chromosomal lacIq allelle (e.g., E.coli D1210, an HB101 derivative) provide tight repression of the P1 replication origin (NOTE: since pSCANS uses an F' origin the lacIq allele can't be carried on a separate F-based plasmid). Induction to high copy can be carried out by addition of IPTG (1mM final concentration). IPTG can be added at different points during growth (to suit your application). For instance, to prepare both cells (e.g., for glycerol stocks) and DNA (e.g., for further cloning) grow the cells to mid log, pull a sample for the glycerol stock, add IPTG and continue growth, prepare DNA from a saturated culture.

Result from experiments shows that for IPTG concentration less than 20 μmol/L, the effect of inducement is scarcely perceivable (mean copy number: 1~3). It also shows that from 20 μmol/L to 100 μmol/L the copy number is induced by IPTG in a way quite proportional to its concentration. It seems that over 100 μmol/L IPTG concentration is “saturated” and a further increase in IPTG concentration cannot raise the copy number (mean copy number: 150±10 in exponentially growing culture).

This result is from exponentially growing culture. For cell culture in stationary phase the mean copy number possibly increases.

repE gene product controls the replication initiation of the plasmid via the F1 replication origin.

Primers for these Biobrick vectors can be found in Part:BBa_G00100 (aka VF2) and Part:BBa_G00101 (aka. VR)

Sequence and Features Content-type: text/html

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[edit]

chassis	lacIq like BBa_V1003
copies	<10 or >100
insert	None
mcs	BioBrick
origin	F' and P1 lytic
resistance	K