Part:BBa_K2033008
N-3-oxo-tetradecanoyl-L-Homoserine lactone* Sender- SinI
This part produces the N-acyl homoserine lactone that acts as a signal for the Sin system.
Sequence and Features
- 10COMPATIBLE WITH RFC[10]
- 12INCOMPATIBLE WITH RFC[12]Illegal NheI site found at 289
- 21COMPATIBLE WITH RFC[21]
- 23COMPATIBLE WITH RFC[23]
- 25COMPATIBLE WITH RFC[25]
- 1000COMPATIBLE WITH RFC[1000]
Short Description
This part produces 6 AHL quorum sensing molecule, which are (C8-HSL) N-[(3S)-2-oxooxolan-3-yl]octanamide, (C12-HSL) N-[(3R)-2-oxooxolan-3-yl]dodecanamide, (3O-C14-HSL) 3-oxo-N-(2-oxooxolan-3-yl)tetradecanamide, (C16-HSL) N-[(3S)-2-oxooxolan-3-yl]hexadecanamide, (3O-9-cis-C16-HSL) (Z)-N-[(3S)-2-oxooxolan-3-yl]hexadec-9-enamide, (C18-HSL) N-[(3S)-2-oxooxolan-3-yl]octadecanamide. This AHL synthase is designed to be inserted into a modular sender vector BBa_K2033011 with a constitutive Tet promoter, 2 ribosome binding sites (RBSs), an RFC10 prefix and mCherry.
Sin System
AHL quorum sensing functions within two modules. The first module, the "Sender," must be induced by certain environmental conditions, usually population density of surrounding organisms. This will begin production of the AHL by the cell, which is then detected by the second module, the "Receiver." Once a certain threshold of AHLs is breached, the Receiver will cause the expression or silencing of certain genes to achieve the desired purpose of the communication, whether it is the production of GFP or to increase growth rate.
The Sin system originates from the soil bacterium Sinorhizobium meliloti. It produces 6 variants of AHLs, of which . The structures is shown below. The alignment below displays the successfully created part, starting from the Tet promoter and ending at the SinI gene with negligible differences in identified nucleotides.
These AHLs have a variety of structures, and each acyl tail structure contributes towards unique transcription factor binding interactions.
The SinI part arises from the soil bacterium Sinorhizobium meliloti. The designed part by Ryan Muller was cloned into competent DH5AT E. coli cells. These were ligated into the psB1C3 vector, plated, and sequenced with the help of ASU's Core Laboratory:
An optical density test was conducted on the produced SinI construct to determine if the AHL is produced. The plate reader ran an 8-hour read from 580-610nm, indicating the presence of the mCherry fluorescent molecule. The AHL gene lies upstream of the mCherry gene, so successful production of mCherry is a good indicator that the AHL molecule is being produced. A positive growth curve was found for the SinI construct over the 8-hour read. The initial dip in mCherry levels was likely the result of the transfer of the cells from an aerated, incubated environment to a 96-well plate. However, overall, mCherry production increased over time, suggesting that the SinI Synthase had been produced in E. coli.
Safety
This section aims to provide safety information and suggestions about the SinI part. The greatest concern from this part is the activation of pathogens via crosstalk. According to Integrated DNA Technologies, quorum sensing genes are not considered dangerous by themselves, as they do not directly cause the creation of a new pathogenic strain. They may contribute to pathogenicity, but so do synthetic promoters. So, the actual AHL molecules are the chief concern.
Crosstalk Partners
SinI is known to work together with the Exp system, which work together to regulate the original SinI host, Sinorhizobium meliloti. Over 200 genes in this bacteria are regulated by SinI. These interactions are shown below. Due to the number of AHL variants produced by this system, it is likely that other bacteria are capable of crosstalking with the Sin system.
Disposal
In order to properly dispose of SinI AHLs, the sample should be autoclaved. Several of these AHLs have a 3-oxo acyl tail, so these (if known) can be degraded with a 10% bleach solution. However, if the specific AHL being produced by the Sin system is unknown, the solution should be autoclaved, which will fully degrade all AHLs. Further details about proper AHL disposal can be found here: http://2016.igem.org/Team:Arizona_State/WhitePaper.
Other Considerations
No other safety information is available for SinI AHLs
References
Hoang, Hanh H. "The LuxR Homolog ExpR, in Combination with the Sin Quorum Sensing System, Plays a Central Role in Sinorhizobium meliloti Gene Expression." Journal of Bacteriology. 186.16 (2004): 5460-5472.
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