| Attribute
| Value
| Strain
| Justification
| Reference
|
| Length | 2μm | MG1655 | Values come from the University of Alberta’s datasheet on MG1655, produced to aid modelling. There is variability in size between strains - for instance, AW405 length varies between 1.5±0.2μm. But University of Alberta datasheet is specifically for MG1655. | [http://redpoll.pharmacy.ualberta.ca/CCDB/cgi-bin/STAT_NEW.cgi University of Alberta]
|
| Diameter | 0.8μm | MG1655 | | [http://redpoll.pharmacy.ualberta.ca/CCDB/cgi-bin/STAT_NEW.cgi University of Alberta]
|
| Shape | Circle r =0.714μm | MG1655 | Actually rod-like. A circle with r= 0.714μm will have equivalent surface area to rod-like. | [http://redpoll.pharmacy.ualberta.ca/CCDB/cgi-bin/STAT_NEW.cgi University of Alberta]
|
| Mass | 1.02x10-13g | MG1655 | Given 1x10-12g for cell wet weight. Dividing this by gravity (=9.81) gives mass. | [http://redpoll.pharmacy.ualberta.ca/CCDB/cgi-bin/STAT_NEW.cgi University of Alberta]
|
| Swimming Speed | 50μms-1 | MG1655 | University Alberta's datasheet gives 50μms-1. However, Swimming speed is affected by:
- Viscosity (as viscosity increases the speed increases to some maximum, then decreases as the viscosity increases further. E.coli (strain:KL227 of length: 1.0μm and diameter: 0.5μm) maximum speed occurs at viscosity 8cp.
- Temperature
- Culture medium
- Vary strain to strain.
- Experimental methods
Many papers give different and variable speeds (mainly for AW405 ~20μms-1). The speed itself is nearly uniform during the run. May need to measure experimentally, don't know under what conditions University of Alberta. Alberta value is higher than other values, but probably because MG1655 is a motile strain.
| [http://redpoll.pharmacy.ualberta.ca/CCDB/cgi-bin/STAT_NEW.cgi University of Alberta], [http://www3.interscience.wiley.com/cgi-bin/fulltext/71003069/PDFSTART A Method for Measuring Bacterial Chemotaxis Parameters in a Microcapillary]
|
| Attribute
| Value
| Strain
| Justification
| Reference
|
| Aspartate concentration detected by E. coli | Over ~5 orders of magnitude, 10nM up to 10mM. Can detect changes of as little as ~0.1% | N/A | Most computer simulations of the chemotaxis pathway based on experimentally determined rates and concentrations predict a minimum detectable concentration of Aspartate at ~200 nM. However, experiments performed by Segall et al. in 1986, (in which E. coli cells are tethered to a coverslip were exposed to small quantities of chemoattractant delivered iontophoretically.) indicated that a change in receptor occupancy of as little as 1/600 could produce an detectable change in swimming behaviour. With a Kd of 1 µM, this corresponds to a minimum detectable concentration of about 2 nM Aspartate. Wild type E. coli cells can detect <10nM of Asp and respond to Asp concentrations of upto 1mM,(responding to over ~5 orders of magnitude). E. coli detect small changes in concentration of 0.1% via temporal comparisons (4s) over a large range ( 10-8 to 10-3 M) | [http://www.jbc.org/cgi/reprint/281/41/30512 Competitive and Cooperative Interactions in Receptor Signalling Complexes]
|
| Temporal comparison of chemotactic gradient | 4 seconds | N/A | The past second has positive weighting, the previous 3 seconds have negative weighting. E coli compares these concentrations (average occupancy of the receptors over the 4s). Models reflecting this have been developed by Segall et al and Schnitzer, cells compare their average receptor occupancy between 4 and 1 s ago c1-4 to the average receptor occupancy during the last second c0-1 . Hence b= c0-1 - c1-4 . If b>0, the cell reduces the tumbling rate to Ttumbling from the ambient value T0 , 1s-1 e.g. b>0 don't tumble. b< 0, tumble at a rate of 1s-1 | [http://www.pubmedcentral.nih.gov/picrender.fcgi?artid=387059&blobtype=pdf Temporal comparisons in bacterial chemotaxis] [http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TBN-4CVRC68-2&_user=121739&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_version=1&_urlVersion=0&_userid=121739&md5=470c7fd73fb9ebf4ca43342f365e221f#sec5.1 Quantitative analysis of signalling networks], [http://web.mit.edu/biophysics/papers/PNAS2003b.pdf Motility of Escherichia coli cells in clusters formed by chemotactic aggregation]
|
| Tumbling angle | Shape parameter 4 Scale parameter 18.32 Location parameter -4.6 | AW405 | Appears not to be dependant on the concentration gradient of chemoattractants/repellents. Nor is there correlation between the length of the run and the change in direction. Used a gamma distribution that fitted the data of Berg and Brown. Non-normality observed by several groups. Suggestions that non-normality was only due to the experimental methods used e.g. in the capillary tube. Tumbling can cause a change in direction when as few as one flagella moves out of the bundle. The flagella on transition from the bundle to release go from normal (a left-handed helix with a pitch of 2.3m and a diameter of 0.4m) to semi coiled (a right-handed helix with half the normal pitch but normal amplitude) and then curly (a right-handed helix with half the normal pitch and half the normal amplitude). | [http://www.nature.com/nature/journal/v239/n5374/pdf/239500a0.pdf Chemotaxis in E. coli anaylsed by three-dimensions], [http://bioinformatics.oxfordjournals.org/cgi/reprint/21/11/2714 AgentCell: a digital single-cell assay for bacterial chemotaxis], [http://jb.asm.org/cgi/reprint/189/5/1756 On Torque and tumbling in swimming Escherichia coli]
|
| Tumble angle direction | Bidirectional | AW405 | Personal communication with Howard Berg. 'The direction is random, more or less, but there is a slight forward bias. It varies from tumble to tumble. The turn-angle distribution peaks at 68° rather than 90°. Tumbles turn out to be more complex than believed in 1972. Motors switch independently, and a tumble can occur if one or just a few motors change their directions of rotation. Tumbles are short, as judged by the tracking microscope, because they involve filament physics rather than motor physics: a transformation in polymorphic form, following motor reversal, from normal to semi-coiled. See Darnton, N.C., Turner, L., Rojevsky, S. and Berg, H.C. On torque and tumbling in swimming Escherichia coli, J. Bacteriol. 189, 1756-1764 (2007).' |
|
| Tumbling time | 0.14±0.19s | AW405 | Exponential distribution fitted (stated to be exponential by Berg and Brown) using only the mean tumble length (not STDEV). | [http://www.nature.com/nature/journal/v239/n5374/pdf/239500a0.pdf Chemotaxis in E. Coli anaylsed by three-dimensional tracking]
|
| Relationship between tumbling angle and time | | | |
|
| Speed while Tumbling | 0μm.s-1 | AW405 | Berg and Brown noted that AW405 slowed/stopped while tumbling. | [http://www.nature.com/nature/journal/v239/n5374/pdf/239500a0.pdf Chemotaxis in E. Coli anaylsed by three-dimensional tracking]
|
| Drift during run | 23±23° | AW405 | Drift was observed. It is what would be expected from rotational diffusion. (at 2.7cp at 32ºC drift was 23±23°). Rotational Brownian motion cause the cell to veer off course, so that in between tumbles the probability density function f of the swimming direction e evolves according to the Fokker-Planck equation. Drift velocity in steep gradient of attractant ~7 µm.s-1(Berg & Turner, 1990) | [http://www.nature.com/nature/journal/v239/n5374/pdf/239500a0.pdf Chemotaxis in E. Coli anaylsed by three-dimensional tracking]
|
| Thrust | Down an Asp gradient 0.41pN, Up an Asp gradient 0.4387pN | AW405 | Average thrust =0.41pN. In the Berg and Brown paper it states that the speed of the bacteria up an aspartate chemotactic gradient increases by 7%. Therefore in our model we shall use the following; thrust DOWN the Asp gradient =0.41pN, up the Asp gradient = 0.4387pN. | [http://www.nature.com/nature/journal/v239/n5374/pdf/239500a0.pdf Chemotaxis in E. Coli anaylsed by three-dimensional tracking], [http://jb.asm.org/cgi/reprint/189/5/1756.pdf On Torque and Tumbling in Swimming E. coli]
|
| Isotropic run lengths | 0.86±1.18s | AW405 | Exponential distribution fitted, this is only an approximate and does not fit exactly (see fig.4 Berg and Brown) The standard deviation is the standard deviation of the mean and has not been used in the exponential distribution | [http://www.nature.com/nature/journal/v239/n5374/pdf/239500a0.pdf Chemotaxis in E. Coli anaylsed by three-dimensional tracking]
|
| Run length UP Aspartate gradient | 1.07±1.80s | AW405 | Exponential distribution fitted, this is only an approximate and does not fit exactly (see fig.6, Berg and Brown). The standard deviation is the standard deviation of the mean and has not been used in the exponential distribution. If Phenylalanine is going to be used as the recruitment chemoattractant it utilises a mutant of the Tar receptor. The mutant Tar receptor has been shown to have comparable chemotactic response to the wild type and therefore the values used for the run lengths of aspartate can also be used for phenylalanine. | [http://www.nature.com/nature/journal/v239/n5374/pdf/239500a0.pdf Chemotaxis in E. Coli anaylsed by three-dimensional tracking], [http://parts2.mit.edu/wiki/index.php/University_of_California_San_Francisco_2006 UCSF wiki]
|
| Run length DOWN Aspartate gradient | 0.8±1.38s | AW405 | Exponential distribution fitted, this is only an approximate and does not fit exactly (see fig.6, Berg and Brown) The standard deviation is the standard deviation of the mean and has not been used in the exponential distribution | [http://www.nature.com/nature/journal/v239/n5374/pdf/239500a0.pdf Chemotaxis in E. Coli anaylsed by three-dimensional tracking]
|
| Attribute
| Value
| Strain
| Justification
| Reference
|
| Viscosity | Viscosity of water is 1.002cP at 20°C | N/A | At present the medium being used by the lab is still be discussed. Currently though the medium most resembles water and therefore the water's viscosity value can be used. This allows us to assume that the medium is Newtonian (dilute aqueous medium that doesn’t contain long unbranched molecules such as methylcellulose or polyvinylpyrrolidone. Note that methlycellulose does not alter the run and tumble statistics, only bundle and motor rotation rates are affected by the addition of methylcellulose). If agar were to be used then the medium would be Non-Newtonian. Even though it would be Non- Newtonian John Hogan in passing said that we could assume it is Newtonian. | [http://arjournals.annualreviews.org/doi/pdf/10.1146/annurev.biochem.72.121801.161737 The rotary motor of bacterial flagella.], [http://jb.asm.org/cgi/reprint/189/5/1756.pdf On Torque and Tumbling in swimming Escherichia coli]
|
| Diffusion coefficient of Aspartate. | 0.033 cm2 .h-1 | N/A | 0.033 cm2 .h-1 is for Aspartate at 22°C in 0.15% agar. Another value from the literature, 0.9 x10-5 cm2 .s-1 , is for aspartate at 35°C in 0.3% agar. To calculate diffusion coefficients the following formula can be used D=RT/6πNvr where: R is the gas constant, T is the absolute temperature (Kelvin), N is the number of molecules in a mole, 6 x1023 , v is the viscosition of the solvent (e.g. 0.001 for water), r= radius of the particle. This formula could be used to calculate the diffusion coefficient at the viscosity used in our experiments. | [http://www.pubmedcentral.nih.gov/picrender.fcgi?artid=1300146&blobtype=pdf Chemotactic Responses of Escherichia coli to Small Jumps of Photoreleased L-Aspartate] [http://www.pnas.org/content/96/20/11346.full.pdf\" Response tuning in bacterial chemotaxis]
|
| Diffusion coefficient of Phenylalanine. | 3.58 x 10-4 cm2 . min-1 | N/A | This value is for phenylalanine in aqueous phase at 25ºC. | [http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TGK-3W38497-D&_user=121739&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000010018&_version=1&_urlVersion=0&_userid=121739&md5=316e71596cb388d2a0cf0de7c15f84fe#fd16 Extraction and re-extraction of phenylalanine by cationic reversed micelles in hollow fibre contactors]
|
| Quorum Signal | OHHL (3-oxo-C6-HSL) | N/A | From the quorum sensing system of Vibrio Fischeri produced by LuxI. Molecular weight: 213 |
|
| Basal (constitutive) rate of AHL production | 30nmol.h-1 | V. fischeri | Value was used in a modelling simulation of the Lux system in V. fischeri. Note that the maximum [AHL] is achieved during stationary phase. | [http://docstore.ingenta.com/cgi-bin/ds_deliver/1/u/d/ISIS/45421751.1/ap/mb/2001/00000309/00000003/art04697/34CECEE65ADECE1112181237349BDA2365FA8246B1.pdf?link=http://bristol.library.ingentaconnect.com/error/delivery&format=pdf Kinectics of the AHL regulatory system in a model biofilmsystem: How many bacteria constitute a Quorum?]
|
| Diffusion coefficient for Quorum signal | Daq = 4.9x 10-6 cm2 .s-1 | N/A | Daq = 4.9x10-6 cm2 .s-1 is the diffusion coefficient of 3 oxo-C12 AHL in water, not OHHL as we would be using. Estimations can be calculated using Wilke Chang equation (see Perry\'s Chemical Engineers\' Handbook). De = 1.23x 10-6 cm2 .s-1 is the effective diffusion coefficient of 3 oxo-C12 AHL in biofilm. | [http://www.springerlink.com/content/v36128k24t558820/fulltext.pdf The effect of the chemical, biological and physical environment on quorum sensing in structured microbial communities. Anal Bioanal Chem (2007) 387:371-380.]
|
| Threshold concentration of autoinducer | Use Imperial iGEM value 1nM! ~1 to 10μg.ml-1 | N/A | In the pattern formation paper fig 2c and d represent a simulation and experimental data respecitively. The graph plots the concentration of AHL required to elicit a visual response (observation of fluorescence). Imperial iGEM team looked at the lower and higher threshold levels of AHL in vivo and in vitro. They also visualised this with expression of GFP. Low threshold 1nM in vivo (estimated the number of plasmids present) in vitro value is only obtained on extrapolation and therefore it is not accurate but predicited to be higher. High threshold is ~1000nM and therefore beyond this level the system does not respond to any further increase, the system is saturated. See graph sheet. Another paper, A novel strategy for the isolation of luxl homologues:evidence for the widespread distribution of a LuxR:Luxl superfamily in enteric bacteria. The V. fischeri sensor for OHHL is very senstive requiring levels of 10ng.ml-1 to inititate transcription. This paper also states that the thresholds differ depending on strain of bacteria and cell densities. The Imperial's iGEM team value is the best as it is for MC1000 and therefore most relevent for this project. | [http://www.nature.com/nature/journal/v434/n7037/pdf/nature03461.pdf A synthetic multicellular system for programmed pattern formation.] [http://parts.mit.edu/igem07/index.php/Imperial/Infector_Detector/F2620_Comparison Imperial iGEM wiki][http://www3.interscience.wiley.com/cgi-bin/fulltext/119307663/PDFSTART A novel strategy for the isolation of luxl homologues: evidence for the widespread distribution of a LuxR:Luxl superfamily in enteric bacteria]
|
| Protein decay (LuxR/AHL) | 0.0231 min-1 | | | [http://www.nature.com/nature/journal/v434/n7037/pdf/nature03461.pdf A synthetic multicellular system for programmed pattern formation.]
|
| LuxR/AHL activation coefficient | 0.01µM | | | [http://www.nature.com/nature/journal/v434/n7037/pdf/nature03461.pdf A synthetic multicellular system for programmed pattern formation.]
|
| LuxR/AHL dimerisation | 0.5µM-3 .min-1 | | | [http://www.nature.com/nature/journal/v434/n7037/pdf/nature03461.pdf A synthetic multicellular system for programmed pattern formation.]
|
| AHL decay | 0.01min-1 | | Note that this value is affected by pH | [http://www.nature.com/nature/journal/v434/n7037/pdf/nature03461.pdf A synthetic multicellular system for programmed pattern formation.]
|
| Particle | 10µm diameter and round | | Value obtained from lab team | [http://nanolab.me.cmu.edu/publications/papers/Behkam-APL2007.pdf Bacterial Flagella-Based Propulsion and On/Off Motion Control of Microscale Objects]
|
| Particle density | 1.05g.cm-3 | N/A | Value is for the particles the lab team is using |
|
| Diffusion coefficient of 10μm polystyrene bead | 4.93x10-14 m 2 .s2 | N/A | | [http://nanolab.me.cmu.edu/publications/papers/Behkam-APL2007.pdf Bacterial Flagella-Based Propulsion and On/Off Motion Control of Microscale Objects]
|
| Drag on 10μm sphere | 1.4pN | N/A | | [http://nanolab.me.cmu.edu/publications/papers/Behkam-APL2007.pdf Bacterial Flagella-Based Propulsion and On/Off Motion Control of Microscale Objects]
|
| Attribute
| Value
| Strain
| Justification
| Reference
|
| T | taxis receptor MW (kDa) = 58-60 | RP437 | Receptor (total) = 15000±1700, Tsr + Tar = 14000±1700, Trg = 440±70. Value was determined in RP437 strain in rich medium. Note that cellular amounts vary 10 fold but the stiochiometric ratios only vary 30%. Segall et al. 1986 assumed that there was 600 Tar receptors per cell (determined in RP437- a strain often used in chemotaxis studies) | [http://jb.asm.org/cgi/reprint/186/12/3687?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&author1=hazelbauer&searchid=1&FIRSTINDEX=0&resourcetype=HWCIT Cellular Stoichiometry of the Components of the Chemotaxis Signaling Complex], [http://www.pdn.cam.ac.uk/groups/comp-cell/Rates.html Bray Computer Modelling group], [http://www.pubmedcentral.nih.gov/picrender.fcgi?artid=387059&blobtype=pdf Temporal comparisons in bacterial chemotaxis ]
|
| R | CheR MW (kDa) = 33 | RP437 | 140 ± 10. Value was determined in RP437 strain in rich medium. | [http://jb.asm.org/cgi/reprint/186/12/3687?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&author1=hazelbauer&searchid=1&FIRSTINDEX=0&resourcetype=HWCIT Cellular Stoichiometry of the Components of the Chemotaxis Signaling], [http://www.pdn.cam.ac.uk/groups/comp-cell/Rates.html Bray Computer Modelling Group]
|
| B | CheB MW (kDa) = 37 | RP437 | 240 ± 10, Value was determined in RP437 strain in rich medium. | [http://jb.asm.org/cgi/reprint/186/12/3687?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&author1=hazelbauer&searchid=1&FIRSTINDEX=0&resourcetype=HWCIT Cellular Stoichiometry of the Components of the Chemotaxis Signaling], [http://www.pdn.cam.ac.uk/groups/comp-cell/Rates.html Bray Computer Modelling Group]
|
| W | CheW MW (kDa) = 18 | RP437 | 6700 ± 890, Value was determined in RP437 strain in rich medium. | [http://jb.asm.org/cgi/reprint/186/12/3687?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&author1=hazelbauer&searchid=1&FIRSTINDEX=0&resourcetype=HWCIT Cellular Stoichiometry of the Components of the Chemotaxis Signaling], [http://www.pdn.cam.ac.uk/groups/comp-cell/Rates.html Bray Computer Modelling Group]
|
| A | CheA MW (kDa) = 71 | RP437 | CheA (total) =6700±1100, CheA (long) 4500±940, CheA (short) = 2200±520. The “short” form of kinase CheA results from an alternative translational start site in E. coli approximately 90 codons interior to the start site that generates the “long” form, CheAL. CheZ does still bind CheAs protein. Modest differences in growth phase can have significant effects on cellular content of chemotaxis components, as previously documented by Wang and Matsumura for CheAL and CheAS | [http://jb.asm.org/cgi/reprint/186/12/3687?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&author1=hazelbauer&searchid=1&FIRSTINDEX=0&resourcetype=HWCIT Cellular Stoichiometry of the Components of the Chemotaxis Signaling], [http://www.pdn.cam.ac.uk/groups/comp-cell/Rates.html Bray Computer Modelling Group]
|
| Y | CheY MW (kDa) = 14 | Ratio of CheY:CheZ =2.3:1 | Values for AW405 6850±1300 molecules/cell (or 27.2±5.2µM) for RP437 2750±275 (or 9.1±0.9µM). Tethering and swimming assays suggest ~30% of CheY is phosphorylated (Alon et al., 1998). Values in the literature for the same and different strains differ greatly but the ratios of CheY:CheZ are very similar (2.3:1). As the swarming ability between AW405 and RP347 are very similar it shows that the ratio rather than the actual numerical value of molecules per cell is the deciding factor. The different values between papers for the same species can be attributed to differences in protein expression and cell volume (this is very dependant on how the cells are grown). The lack of regulated conditions for cell growth mean that any value used in modelling will not be accurate. As the majority of values for molecules per cell are for RP347 use values for RP437 | [http://jb.asm.org/cgi/reprint/180/19/5123 CheZ Has No Effect on Flagellar Motors Activated by CheY13DK106YW ], [http://www.pdn.cam.ac.uk/groups/comp-cell/Rates.html Bray Computer Modelling Group], [http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1170757 Response regulator output in bacterial chemotaxis]
|
| Z | CheZ MW (kDa) = 24 | 24 | 3050 ±580 (12.1±2.3µM) (AW405), 1170 ± 170 (3.9±0.5µM) (RP437) the different values between papers for the same species can be attributed to differences in protein expression and cell volume (this is very dependant on how the cells are grown). The lack of regulated conditions for cell growth mean that any value used in modelling will not be accurate. As the majority of values for molecules per cell are for RP347 use values for RP437 | [http://jb.asm.org/cgi/reprint/180/19/5123 CheZ Has No Effect on Flagellar Motors Activated by CheY13DK106YW ]
|
| M | FliM MW (kDa) = 38 | 38 | 37±13 copies per flagella. Determined in salmonella but the value has be used by other groups when referring to E. coli | [http://jb.asm.org/cgi/content/abstract/178/1/258?ijkey=b6d6fd8a1c8564ac118449c4acdff535727e46d6&keytype2=tf_ipsecsha FliG and FliM distribution in the Salmonella typhimurium cell and flagellar basal bodies]
|
| a | aspartate | N/A | N/A |
|
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