Monomeric Photoconvertible Fluorescent Protein for Imaging of Dynamic Protein Localization

Allele Biotech has just made a news announcement indicating that researchers from Dr. Campbell’s lab at the University of Alberta, Canada, and scientists at Allele Biotech Drs. Nathan Shaner and Jiwu Wang published a paper in the Journal of Molecular Biology on July 5th introducing a new photoconvertible fluorescent protein mClavGR.

The use of green-to-red photoconvertible fluorescent proteins (FPs) enables researchers to highlight a subcellular population of a fusion protein of interest and image its dynamics in live cells. In an effort to enrich the arsenal of photoconvertible FPs and overcome the limitations imposed by the oligomeric structure of the natural photoconvertible FPs, we designed and optimized a new monomeric photoconvertible FP. Furthermore, we have exploited mClavGR2 to determine the diffusion kinetics of the membrane protein intercellular adhesion molecule 1 (ICAM-1) both when the membrane is in contact with a T lymphocyte expressing leukocyte function-associated antigen 1 (LFA-1) and when it is not. These experiments clearly establish that mClavGR2 is well suited for rapid photoconversion of protein sub-populations and subsequent tracking of dynamic changes in localization in living cells.

Compared with previously available photoconvertible FPs, mClavGR2 has much improved photostability of the red state under confocal illumination conditions, 3644 over mEOS2’s 2700 and Dendra2’s 2420. Most notable among other advantages of mClavGR2 is its monomeric structure, its highly optimized and relatively rapid folding efficiency, and its high photoconversion effi ciency due to the high pKa of the green state. Its brightness in both the green and the red states is similar to the popular mCherry.

In regard to monomeric state, the monomeric variant of EosFP, known as mEos, was created through the introduction of two point mutations that disrupted the protein-protein interfaces of the tetrameric species. Expression of mEos at temperatures of greater than 30 °C is problematic, but an effectively monomeric tandem dimer variant does express well at 37 °C. mEos2 has been reported to retain some propensity for dimer formation.

We anticipate that this new addition to the toolbox of engineered FPs will be of great utility in imaging of fast protein dynamics in live cells. Experiments to determine whether the advantages of mClavGR2 translate to improved performance in super-resolution imaging applications have been initiated.

Hiofan Hoi(a), Nathan C. Shaner(b), Michael W. Davidson(c), Christopher W. Cairo(a), d, Jiwu Wang(b) and Robert E. Campbell(a)
a University of Alberta, Department of Chemistry, Edmonton, Alberta, Canada T6G 2G2
b Allele Biotechnology, 9924 Mesa Rim Road, San Diego, California 92121
c National High Magnetic Field Laboratory and Department of Biological Science, The Florida State University, 1800 E. Paul Dirac Dr., Tallahassee, Florida 32310
d Alberta Ingenuity Centre for Carbohydrate Science
Received 20 February 2010; revised 15 June 2010; accepted 25 June 2010. Available online 5 July 2010.

New Product of the Week 070510-071110: mClavGR greeen-to-red photoconvertible fluorescent protein, catalogue number to be created

Promotion of the Week 070510-071110: Purified lanYFP, bright even in SDS-PAGE gel WITHOUT dye or excitation, great for in gel marker.

Tags: Dendra2, dynamic imaging, FP, FPs, mCherry, mEOS, mKirGR, PALM, photoconvertible, photoswitchable, STORM

Allele Custom Services for Drug Screening Companies

Many target discovery and validation programs can benefit from RNA interference, fluorescent proteins, stem cells, and viral delivery systems. However, applications of these technologies require special reagents and laboratory know-how. Even when available, many generic reagent kits are not tailored for your particular needs in screening or validation.

At Allele, we accelerate your discovery efforts with custom RNAi screening, fluorescence based assays, and cell model development services.

1) Our RNAi platform, based on our patented shRNA/miRNA technologies, use DNA linear template, plasmid, lentivirus, retrovirus, or baculovirus vectors that prompt cells to endogenously express RNAi. As a result, our screens offer advantages over synthetic siRNAs:
• Higher levels of consistency
• Greater delivery and gene silencing efficiencies
• Accessibility to difficult-to-transfect cells, including primary cells
• Potential for inducible RNAi expression
• More persistent silencing with shRNA under Allele’s own IP–you may not need to license siRNA patents!

2) Fluorescent proteins (FPs), which can span the entire visual spectrum, have become some of the most widely used genetically encoded tags. Genes encoding FPs alone or as fusions to a protein of interest may be introduced to cells by a number of different methods, including simple plasmid transfection or viral transduction. Allele Biotech is one of a few companies that develop and improve FPs through fundamental research. We have so far achieved:
• The brightest cyan and green FPs, true monomers for minimum artifact or cytotoxicity
• The brightest yellow and red FPs from lancelet, only FPs from vertebrate
• mTFP1 as the best FRET donor by 3 independent reports
• Photoconvertible FPs for super imaging or kinetic labeling
• Delivery on plasmid, retrovirus, lentivirus, baculovirus vectors

3) As a major advancement in the stem cell field, it has recently been shown that mouse and human differentiated cells may be reprogrammed into stem-like, pluripotent cells by the introduction of defined transcription factors. These induced stem cells (iPSCs) provide unprecedented resources of cells of different differentiation stages for functional testing and drug screening. Allele Biotech develops and provides state-of-the-art reagents in convenient forms for iPSC production
• iPS factors carried on lentivirus, retrovirus, baculovirus for different cell types
• Availability in combination with fluorescent proteins under own IP, and drug resistant genes
• 4-in-1 or 2-in-1 effective use of iPS factors on one viral vector
• Feeder cells of human origin expressing factors essential for stem cell culturing

4) Introduction of protein factors, miRNA, promoter-reporter, and virtually any other genetic element of interest via the most efficient viral packaging systems.
• Introducing protein-FP fusion, promoter-FP reporter, photoactivatable factors for cell-based assays
• Introducing critical factors for cell immortalization
• Episomal or integrated expression using baculoviral vectors
• High throughput, systematic expression of whole class of molecules in any type of cell
• High titer viral packaging at low cost for delivery to animal tissues

In addition, the Allele team can provide custom-designed assays that can be used for assaying enzyme activities in almost any pathway, such as the EGF pathway, TNF response/apoptosis pathway, nuclear receptors, etc. We utilize technically advanced methods to provide our partners with advantages over alternative methods or other services.

New Product of the Week 06-28-10 to 07-03-10: Eco-friendly mammalian tissue culture plates, 40% less plastic to the environment, 40% less cost to your budget, contact our sales rep today for quotes and details.

Promotion of the Week 06-28-10 to 07-03-10: Oct3/4 iPS lentivirus with RFP as marker, new to the market, this week only all kits containing Oct3/4-RFP same price as the original, non-RFP versions, save ~$50!

Tags: cell assays, cell based assays, cell culture, drug screening, FP assays, FRET, iPS cells, kinase assasy, pathway, RNAi

Brightest Ever Fluorescent Protein

LanYFP, identified from lancelet (also known as amphioxus, e.g. Branchiostoma floridae), has been found to have the following properties:

Excitation 513nm
Emission 524nm
Quantum yield 0.95
Extinction coefficient 150,000
pKa ~3.5
Salt insensitive 0-500mM NaCl

LanYFP has a brightness of 143! For comparison, the brightness of the previously known brightest FPs is 95 for tdTomato, and 34 for commonly used EGFP.

Allele already has been exclusively providing the brightest cyan FP in mTFP1 (brightness of 54); and the brightest green FP in mWasabi (brightness of 56). The confirmation of LanYFP as the brightest ever FP is a major milestone of Allele’s research and development efforts in the fluorescent protein field. We are currently monomerizing LanYFP and another lancelet protein, LanRFP. Once completed, the new proteins should definitely be the FPs of choice for in vivo imaging and FRET with unprecedented utilities.

Promotion of the week 062010-061610: Validated Rex1 Promoter Reporter Lentiviral Particles-1 Vial for $149.00 (ABP-SC-RREX2R1). Save $59 if place an order this week! http://www.allelebiotech.com/shopcart/index.php?c=200&sc=34

New product of the week, recombinant mTFP1, mWasabi, LanYFP, LanRFP, $159 for 125 ug, compare price for 100ug vs 125ug in other companies’ offers, you will know that you are getting a good deal from Allele.

Tags: brightest FP, fluorescent protein, Fluorescent proteins, FP, FP brightness, FPs, Lancelet, monomer FP, monomerization, mTFP1, mWasabi, RFP, YFP

Developing Cell-Based Assays

Cascaded protein interactions form the foundation of all signaling pathways, many of which are involved in multiple human diseases. These interactions are sensitively and precisely regulated by various post-translation modifications such as phosphorylation, acetylation, ubiquitination, etc. Many action points of the protein modifications have been targeted during drug development. From a survey we have conducted on assays aimed at these targets, we found that most of the assays are based on the enzymatic reactions, e.g. phosphorylation-specific ELISA, and chemically modified FRET, which require pre-assembled reagent kits which are hard to apply to different targets and different cell models.

Fluorescent Protein based FRET might be the optimal choice to develop a versatile cell-based assay. Since signaling pathways rely on hierarchical protein-protein interactions, the most direct and precise way to study cell signaling pathways would be to detect the interactions between a target protein and its immediate downstream protein. Furthermore, different upstream signals can activate the same set of target proteins in different post-modification patterns, resulting in specific activation of downstream responding factors. These signal flows may be individually monitored by using FRET based assay redesigned and validated for each downstream pathway.

Allele’s scientists can develop cell-based assays with in-depth understanding of protein interactions within the context of human genome, such as the SH2, SH3 and PTB domains in tyrosine kinase signaling, the F-box, BTB-box, SOCS, WDR, and LRR domains in the ubiquitin proteasome system, etc. Additionally, Allele’s cell-based assays can be carried on world’s most powerful lentivirus packaging platform, suitable for virtually all different cell lines and primary cells.

New Product of the Week 061410 to 062010: Rat monoclonal antibody against GFP, strong signal for GFP labeling

Promotion of the Week 061410 to 062010: Mouse LIF-bFGF expressing feeder cells for stem cell culture (ABP-SC-BLIFM05), one vial free to go with any iPS lentivirus/retrovirus kit.

Tags: BTB-box, cell based assays, F-box, FRET, LRR domain, pathway, signaling pathway, SOCS, WDR domain

Introducing EcoCulture Tissue Culture Plates

Allele Biotech is scoring one for the environment again. Our brand new EcoCulture Tissue Culture Dishes are designed with up to 40% less plastic than other brands, helping us attain our goal to minimize the menacing need for plastic consumables in the lab. Our high tech, environmentally friendly EcoCulture Dishes demonstrate much better imaging capabilities because of the thin lay of plastic at the bottom, and stronger physical strength even using only 60% plastic due to their patented design, aiding the environment by reducing energy consumption and decreasing the amount of plastic that will end up on our planet. An all inclusive environmental effort surrounds this brand new product line with our added commitment of donating 1% of profits from EcoCulture sales to an environmental aid organization (to be determined).

EcoCulture Dishes were a natural progression for Allele Biotech product design. For a long time our operations have included environmentally friendly endeavors; our recycling program which we conduct at a cost to us, our Box Swap program designed to reuse and reduce the need for Styrofoam, and our packaging methods that emphasize minimal use of materials as a long time company policy have all been executed in the interest of the environment. We have striven toward the belief that you do not have to sacrifice the planet in the name of research and the launch of our EcoCulture Dishes aims to spread our altruistic philosophies to our customers and partners in research!

Brochures and catalogue numbers of these products will become listed on our webpages shortly. Visit us often or follow us on Facebook, twitter, or myspace for updates on all our weekly promotions and new products of the week.

Promotion of the week: Falcon 96-well tissue culture grade plates giveaway–buy 1 bottle of our top quality FBS (validated for both mammalian and insect cells), receive 3 packages of 5×96 Falcon 3075 flat bottom tissue culture plates for free!

Promotion of the week 060710-06310: iPS factors with fluorescent protein tracers on ready-to-use high titer lentivirus, currently available-Oct3/4 with RFP and c-Myc with RFP, more to be added.

Tags: biotech and planet, c-Myc RFP, environmental charity donation, environmentally conscious business, Oct3/4 promoter GFP, tissue culture plates