ARCUS Protein – Making the Cut – in Space (ARCUS Protein – Making the Cut – in Space) - 11.21.18

Overview | Description | Applications | Operations | Results | Publications | Imagery

ISS Science for Everyone

Science Objectives for Everyone
ARCUS Protein – Making the Cut – in Space is a student investigation that works alongside Precision Biosciences to determine how microgravity affects the ability of a synthetic nuclease. The synthetic enzyme ARCUS is meant to make a specific double-stranded break in deoxyribonucleic acid (DNA) and may be further used to fix, add or knockout genes. This is the first step to determine whether the technology has potential to sustain habitats outside Earth.
Science Results for Everyone
Information Pending

The following content was provided by Karen Kingrea, and is maintained in a database by the ISS Program Science Office.
Experiment Details


Principal Investigator(s)
Karen Kingrea, Immaculata Catholic School, Durham, NC, United States

JoAnn Hux, M.S., Precision Sciences, Durham, NC, United States

Precision Biosciences, Durham, NC, United States
Immaculata Catholic School , Durham, NC, United States

Sponsoring Space Agency
National Aeronautics and Space Administration (NASA)

Sponsoring Organization
National Laboratory Education (NLE)

Research Benefits
Information Pending

ISS Expedition Duration
October 2018 - April 2019

Expeditions Assigned

Previous Missions
Information Pending

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Experiment Description

Research Overview

  • ARCUS Protein – Making the Cut – in Space consists of students that use Precision BioSciences’ genome editing technology to test a synthetic enzyme in microgravity.
  • The ARCUS nucleases may be customized to recognize a deoxyribonucleic acid (DNA) sequence within any target gene.
  • Precision BioSciences’ genome editing technology has been tested in plants, animals and human DNA, and it may fix, add or knockout genes.
  • The investigation consists of MixStix or flexible tubes that have sections sealed off with clamps. One section has purified ARCUS nuclease in powder form and another has a solution of plasmid DNA (small circular, double-stranded DNA molecules).
  • A clamp is released to allow the mixture of ARCUS nuclease and plasmid DNA to combine. After a one-hour incubation, a second clamp is released to allow a stop solution to terminate the reaction.
  • ARCUS Protein – Making the Cut – in Space tests whether the nuclease under microgravity is successful at binding to the DNA and making a double stranded break. Successful function of this enzyme in a space environment could help support humans, plants and animals in adapting to life outside Earth.


ARCUS Protein – Making the Cut – in Space is a student investigation that tests Precision BioSciences’ genome editing technology aboard the International Space Station (ISS). Space Center Houston (SCH), the official visitor center to Johnson Space Center, runs a five-day engineering design program called Space Center University. The SCH Education department chose a team from the Immaculata Catholic Middle School in North Carolina to design an investigation for microgravity. The student team works alongside Precision BioSciences from North Carolina to design the investigation.
Precision BioSciences’ ARCUS technology is a next-generation genome editing platform derived from a natural genome editing enzyme called a homing endonuclease. Homing endonucleases are nature’s genome editing system. They are site-specific DNA-cutting enzymes encoded in the genomes of many eukaryotic species. Homing endonucleases have the unusual ability to precisely recognize long DNA sequences (12-40 base pairs) that are typically rare enough to occur only once in a complex genome. These non-destructive enzymes trigger gene conversion events that modify the genome in a very precise way, most frequently by the insertion of a new DNA sequence. The ability to target a single DNA break in a complex genome and to achieve gene modification without random off-targeting makes homing endonucleases the ideal starting material for a therapeutic-grade genome editing technology.
The backbone of the ARCUS technology is the ARCUS nuclease – a fully synthetic enzyme similar to a homing endonuclease but significantly improved to be the starting point for a therapeutic-grade genome editing platform. The ARCUS nuclease is small and may be customized to recognize a DNA sequence within any target gene. ARCUS nucleases are created using a set of proprietary in silico (computer simulations) and lab-based techniques to ensure maximum gene editing efficiency with minimum off-target activity. Importantly, ARCUS nucleases may be optimized to control potency and specificity based on the analysis of cutting activity in a relevant model organism.
The 15 students are split into two groups while developing the investigation. Group 1 isolates a histidine (HIS) tagged ARCUS nuclease protein over a nickel sepharose (a type of agarose gel) drip column. The students load the column with a protein lysate pre-prepared for them, wash the column, and elute the final protein. Group 2 isolates a plasmid that contains the 22-base recognition sequence specific to the nuclease isolated by Group 1. The nuclease protein and plasmid DNA are placed in separate sections of a MixStix by the students at SCH. One of the prepared MixStix is then ready to be flown to the ISS, while the other serves as a ground control at Precision BioSciences headquarters in Durham, North Carolina.
On Earth, ARCUS nucleases have been used to engineer plants and animals, and cell and gene therapies for humans are now being developed. With the current expansion of both the genome editing field and human spaceflight, it is increasingly likely that a genetically edited organism may be generated, or that gene therapy may be administered, in a microgravity environment. The objective of this investigation is to determine the effect of a microgravity environment on an ARCUS nuclease’s ability to create a specific double-stranded break in DNA as a first step to determine whether this technology has potential in an extraterrestrial habitat. Genome editing might be very important if and when there is a need to sustain the human population in space, on the moon, or on another planet.

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Space Applications
The ARCUS enzyme may be customized to recognize DNA sequences within any target gene. It generates a double-stranded break in DNA, making it possible to make genetic insertions, deletions or edits at that site. This investigation tests whether the technology works in microgravity, where gene editing might be used to help sustain a human population in space or on another planet or to produce food from plants and other organisms for long-term missions.

Earth Applications
Precision BioSciences genome editing technology is being developed on Earth to repair genes, develop gene therapies, attack cancer cells, and modify genes in plants to create more productive crops. Demonstrating its function in microgravity to repair genes and develop gene therapies advances continued development and application of this technology on Earth.

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Operational Requirements and Protocols

Students prepare and pack their investigation at Space Center University at SCH so that it is ready for execution aboard the ISS.
Investigation preparation consists of a MixStix divided into three sections that contain the DNA, nuclease, and stop solution. The sections are sealed by removable clamps. Purified ARCUS nuclease is precipitated and stored in powder form, and the plasmid DNA is stored in liquid form. The first clamp to be unclamped by a crew member mixes 120 µg ARCUS nuclease precipitated in powder form and 450 µg plasmid DNA suspended in 3 mL of 100 mM sodium chloride (NaCl), 50 mM Tris hydrochloride (Tris-HCl), 10 mM magnesium chloride (MgCl2), 100 µg/mL Bovine serum albumin (BSA) (pH 7.9). After at least one hour of incubation time, the second clamp is unclamped, mixing the stop solution (1% sodium dodecyl sulfate, 50 mM ethylenediaminetetraacetic acid EDTA], pH 8.9) with the DNA and enzyme mix. The ARCUS nuclease activity is evaluated after return to Earth by gel analysis to elucidate the DNA fragmentation due to cutting by the nuclease.

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Decadal Survey Recommendations

Information Pending

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Results/More Information

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Related Websites
Precision BioSciences

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