NanoBRET™ Assays to Analyze Virus:Host Protein:Protein Interactions in Detail

Posted on by Kyle Hooper

Recently, Gordon et al. published an atlas of protein:protein interactions of all proposed SARS-CoV-2 proteins expressed individually in HEK 293 cells (Table 1). The study tagged each of the viral proteins with an epitope tag and performed a pull-down of the expressed protein followed by trypsin digestion and mass spec analysis, a process referred to as affinity purification–mass spec analysis. The group identified 332 human proteins interacting with 27 SARS-CoV-2 proteins.

The interactions identified in the HEK 293 cells helped Appelberg et al. analyze interactions over time in SARS-CoV-2-infected Huh7 cells. Gordon et al. used the PPI data to identify FDA-approved drugs, drugs in clinical trials, and pre-clinical compounds that bound to the identified human proteins and labs in New York and Paris tested some of these drugs for antiviral effects.   

Table 1. The general functional area of human proteins identified to interact with individually expressed SARS-CoV-2 proteins as reported by Gordon, et al. (1). The SARS-CoV-2 proteins are classified as non-structural proteins (nsp#), structural proteins (E, M, and N) and accessory proteins (orf#).  
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Using Wastewater Surveillance to Track COVID-19 Outbreaks

Posted on by Promega

Today’s blog is written by guest blogger, Sameer Moorji, Director, Applied Markets.

Even as countries are now gradually starting to reopen after lockdown, the COVID-19 pandemic is far from over. Researchers around the world continue to find new ways to monitor, prevent and treat the disease. One new way of monitoring COVID-19 outbreaks relies on a somewhat unexpected source: sewage water.

In March 2020, researchers at the KWR Water Research Institute found the presence of SARS CoV-2 RNA in wastewater samples collected near Schiphol airport in Amsterdam and several other sites in Netherlands. The result came within a week after the first case of COVID-19 in the country was confirmed. This study opened the door to the possibility of using wastewater-based epidemiology to determine population-wide infections of COVID-19.

What is Wastewater-based epidemiology?

Wastewater based epidemiology (WBE), or sewershed surveillance, is an approach using analysis of wastewater to identify presence of biologicals or chemicals relevant for public health monitoring. WBE is not new, as wastewater has previously been used to detect the presence of pharmaceutical or industrial waste, drug entities (including opioid abuse), viruses and potential emergence of super bugs. In fact, several countries have been successful in containing Polio and Hepatitis A outbreaks within their geographic locations.

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Promega Leverages Long-Time Experience in MSI Detection with European Launch of CE-Marked IVD Assay for Microsatellite Instability

Posted on by Kelly Grooms

The genetic abnormality called microsatellite instability, or MSI, has been linked to cancer since its discovery in 1993 (1). MSI is the accumulation of insertion or deletion errors at microsatellite repeat sequences in cancer cells and results from a functional deficiency within one or more major DNA mismatch repair proteins (dMMR).  This deficiency, and the resulting genetic instability, is closely related to the carcinogenicity of tumors (2).

Historically MSI has been used to screen for Lynch Syndrome, a dominant hereditary cancer propensity. More recently, tumors with deficient MMR function have been identified as being more likely to respond to immune checkpoint inhibitor (ICI) therapies (3.). Because MSI can be the first evidence of an MMR deficiency, MSI-High status is predictive of a positive response to immunotherapies such as ICI therapies. (3).

Learn more about MSI in this short animation.
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The Marine Biological Lab: Finding Answers Beneath the Ocean

Posted on by Johanna Lee
cuttlefish

Marine animals are fascinating. Not only are their appearances alien-like (think tentacles, suckers and bioluminescence). But many have also developed unique capabilities unlike anything you see on land.

In fact, most of the biodiversity of the world lies beneath the ocean. According to the World Register of Marine Species, there are more than 400,000 marine species, and it is estimated that 91% of marine species have yet to be identified. Studying marine animals may help us learn more about how we evolved and even lead to new ways to study and treat human diseases. At the forefront of marine biology research is the Marine Biological Lab (MBL), located in Woods Hole, Massachusetts.

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Choices for Measuring Luciferase-Tagged Reporter Pseudotyped Viral Particles in Coronavirus Research

Posted on by Kyle Hooper

Coronavirus (CoV) researchers are working quickly to understand the entry of SARS-CoV-2 into cells. The Spike or S proteins on the surface of a CoV is trimer. The monomer is composed of an S1 and S2 domain. The division of S1 and S2 happens in the virus producing cell through a furin cleavage site between the two domains. The trimer binds to cell surface proteins. In the case of the SARS-CoV, the receptor is angiotensin converting enzyme 2. (ACE2). The MERS-CoV utilizes the cell-surface dipeptidyl peptidase IV protein. SARS-CoV-2 uses ACE2 as well. Internalized S protein goes though a second cleavage by a host cell protease, near the S1/S2 cleavage site called S2′, which leads to a drastic change in conformation thought to facilitate membrane fusion and entry of the virus into the cell (1).  

CDC / Alissa Eckert, MS; Dan Higgins, MAMS

Rather than work directly with the virus, researchers have chosen to make pseudotyped viral particles. Pseudotyped viral particles contain the envelope proteins of a well-known parent virus (e.g., vesicular stomatitis virus) with the native host cell binding protein (e.g., glycoprotein G) exchanged for the host cell binding protein (S protein) of the virus under investigation. The pseudotyped viral particle typically carries a reporter plasmid, most commonly firefly luciferase (FLuc), with the necessary genetic elements to be packaged in the particle. 

To create the pseudotyped viral particle, plasmids or RNA alone are transfected into cells and the pseudotyped viruses work their way through the endoplasmic reticulum and golgi to bud from the cells into the culture medium. The pseudoviruses are used to study the process of viral entry via the exchanged protein from the virus of interest. Entry is monitored through assay of the reporter. The reporter could be a luciferase or a fluorescent protein.   

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The Surprising Landscape of CDK Inhibitor Selectivity in Live Cells

Posted on by Promega

Cyclin-dependent kinases (CDKs) are promising therapeutic targets in cancer and are currently among the most intensely studied enzymes in drug discovery. The FDA has recently approved three drugs for breast cancer that target members of this kinase subfamily, fueling interest in the entire family. Although broad efforts in drug discovery have produced many CDK inhibitors (CDKIs), few have been characterized in living cells. So just how potent are these compounds in a cellular environment? Are these compounds selective for their intended CDK target, or do they bind many similar kinases in cells? To address these questions, teams at the Structural Genomics Consortium and Promega used the NanoBRET™ Target Engagement technology to uncover surprising patterns of selectivity for touted CDKIs and abandoned clinical leads (1). The results offer exciting opportunities for repurposing some inhibitors as selective chemical probes for lesser-studied CDK family members.

CDKs and CDKIs

nanobret technology for kinase target engagement

Cyclin-dependent kinases (CDKs) regulate a number of key global cellular processes, including cell cycle progression and gene transcription. As the name implies, CDK activity is tightly regulated by interactions with cyclin proteins. In humans, the CDK subfamily consists of 21 members and several are validated drivers of tumorigenesis. For example, CDKs 1, 2, 4 and 6 play a role in cell cycle progression and are validated therapeutic targets in oncology. However, the majority of the remaining CDK family is less studied. For example, some members of the CDK subfamily, such as CDKs 14–18, lack functional annotation and have unclear roles in cell physiology. Others, such as the closely related CDK8/19, are members of multiprotein complexes involved broadly in gene transcription. How these kinases function as members of such large complexes in a cellular context remains unclear, but their activity has been associated with several pathologies, including colorectal cancer. Despite their enormous therapeutic potential, our knowledge of the CDK family members remains incomplete.

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38 Years After First Release, RNasin Protects COVID-19 Tests

Posted on by Jordan Villanueva

A protein first purified and sold by Promega almost four decades ago has emerged as a crucial tool in many COVID-19 testing workflows. RNasin® Ribonuclease Inhibitor was first released in 1982, only four years after the company was started. At that time, the entire Promega catalog fit on a single sheet of 8.5 × 11” paper, and RNasin was one of the first products to draw widespread attention to Promega. Today, the demand for this foundational product has skyrocketed as it supports labs responding to the COVID-19 pandemic.

What is RNasin® Ribonuclease Inhibitor?

RNA is notoriously vulnerable to contamination by RNases. These enzymes degrade RNA by breaking the phosphodiester bonds forming the backbone of the molecule. To say that RNases are everywhere is barely an exaggeration – almost every known organism produces some form of RNase, and they’re commonly found in all kinds of biological samples. They’re easily introduced into experimental systems, since even human skin secretes a form of RNase. Once they’re present, it’s very hard to get rid of them. Even an autoclave can’t inactivate RNases; the enzymes will refold and retain much of their original activity.

RNasin® Ribonuclease Inhibitor is a protein that has been shown to inhibit many common contaminating RNases, but without disrupting the activity of enzymes like reverse transcriptase that may be essential to an experiment. It works by binding to the RNase enzyme, prevent it from acting on RNA molecules. This is important for ensuring that RNA samples are intact before performing a complex assay.

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Understanding the Structure of SARS-CoV-2 Spike Protein

Posted on by Gary Kobs

Glycosylation is the process by which a carbohydrate is covalently attached to target macromolecules, typically proteins. This modification serves various functions including guiding protein folding (1,2), promoting protein stability (2), and participating signaling functions (3).

ribbon structure of SARS-CoV-2 protein
Ribbon Structure of SARS-CoV-2 Spike Protein

SARS-CoV-2 utilizes an extensively glycosylated spike (S) protein that protrudes from the viral surface to bind to angiotensin-converting enzyme 2 (ACE2) to mediate host-cell entry. Vaccine development has been focused on this protein, which is the focus of the humoral immune response. Understanding the glycan structure of the SARS-CoV-2 virus spike (S) protein will be critical in the development of glycoprotine-based vaccine candidates.

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Working from Home: Finding Productivity in this New Normal

Posted on by Grant Kees

During this time of adjusting to a new normal, one of the most difficult things that I have had to get used to is being productive in my own home. Work from home (WFH) days are embraced by some people and not by others. For me, transitioning from working in an office and school setting, to working at-home and completing online courses, has led me on a search for answers about how to get the most out of my day. After creating a productive at-home work environment for me, I wanted to share some of my findings with you.

Here are some of the tips that I have found useful:

Section out a portion of your home for work only.

When I first started working from home, I moved room to room working wherever I felt most comfortable. I soon found this affected my organization and time management, so I started keeping all my work in one area. Now, as I sit here writing this post, I know where all of my work is, and I also know that when I walk out of this area I can ‘power down’ my mind knowing I no longer have to do work.

Power off your electronics when not working.

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ADCC and Fc Effector Functions: Considerations for COVID-19 Vaccine Development

Posted on by Jordan Villanueva

As we continue navigating the challenges presented by COVID-19, several research areas are crucial for helping us slow the infection rate and ending the pandemic. Advanced testing methods, such as antibody testing, help us understand and predict how the virus will spread, which can inform policy decisions. Effective therapeutics will influence clinical outcomes for individual patients, and several drugs are already being tested or administered. However, an effective vaccine against the SARS-CoV-2 virus is perhaps the most important tool we can use to protect individuals and populations from COVID-19.

Over 90 vaccines against the SARS-CoV-2 virus are currently in development around the world. While there are many different types of vaccines, the overall goal is to create long-lasting protective immunity by stimulating the production of specific antibodies. As these vaccine candidates are further characterized, monitoring ADCC activity can provide important insights into their potential efficacy.

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