Overview

Optopass is an optogenetic passcode system for S. cerevisiae. This revolutionary system simultaneously meets the needs of safety and security. There is a broad range of applications, and we envision the use by so many stakeholders, including not only researchers and companies but also citizens. Optopass will contribute to the further development of synthetic biology.

How to implement Optopass in the real world?

After many human practices, we realized that Optopass can contribute to society in two main ways. First, as a safety system: one in which all cells die when exposed to sunlight, and second, as a security system: one in which the target genes are not expressed unless they are exposed to specific colors of light in the correct order.

By refining and interconnecting these two aspects, Optopass can offer suitable products for a wide range of end users.

Based on human practices, we considered three types of end users and designed Optopass products to suit each of them by combining the two systems: safety and security. The following Figure 1 is a simple illustration of our plan.

As for the safety aspect, we mainly target citizen science. When citizens use synthetic biology, there are concerns about the release of GMOs into the environment due to human error, and this has to be avoided. Using Optopass, we can make GMOs kill themselves just by their exposure to sunlight, without using any toxic substances, which enables the safe use of GMOs. As for the security aspect, we suppose large data centers that store DNA storage as the end users. We envisioned a system that enhances information security of the DNA storage by inserting the DNA with the Optopass system into a yeast so that the DNA will be fragmented under white light by the kill switch.In addition, the target sequence cannot be obtained even if the microorganism is stolen as long as the passcode is unknown. Furthermore, using the basis of Optopass, the gene sequence can be redesigned so that the target sequence cannot be identified, even if it is sequenced .

By combining these two safety and security aspects of Optopass, we suppose researchers who handle pathogenic bacteria in laboratories at universities or research institutes as users. In this case, they have to be careful of both not to leak the GMOs to the outside world, which is biosafety, and avoiding the GMO to be used for dual-use, which is biosecurity. For them, it is essential to ensure biosafety and biosecurity simultaneously. Using Optopass, it would be possible to control the expression of the toxic substances by the light inputs so that it would express the programmed substances only when the correct order of light input is applied, whereas making them die when exposed to the wrong color or sunlight.

As shown in the examples above, Optopass can provide solutions to various entities in terms of safety and security. We hope to approach even more entities in the future by continuing human practices to explore the application of our system. Using the order of lights to control to ensure safety and security is already a novel idea. Yet, our system also enables the design of products that provide both safety and security systems at the same time, vastly expanding the possibilities for products in these two areas.

Challenges

For DNA storage

• Cell-free systems may be more appropriate in this case. We would like to consider whether DNA needs to be stored in real organisms such as yeast, and identify the demand of Optopass in the security of DNA storage in more detail and draw a product design.

For laboratory use

• Since it requires a high level of security, we may need to consider increasing the cipher length and/or the numbers of colors of optical stimuli. It is necessary to look for non-interfering recombinases and/or high specificity photoreceptors to prevent interference between light wavelengths.

In addition to the use of GMOs, there are other safety and functional issues that need to be addressed. In the Optopass project, the order of light is used as a passcode. Theoretically, up to 1,536 different passcodes can be created from three types of stimuli and the cipher length of ten, but to build a reliable security system, more various stimuli are necessary. It would be desirable to use cyan or yellow light as well as red, blue, green, and UV-B, which we considered. However, we must consider wavelength characteristics when increasing the number of colors. It is hoped that proteins with high specificity to wavelengths will be found to prevent malfunctions.

Usability also remains a challenge. While our optogenetic passcode system improves in security as the length of the cipher increases, it also becomes more laborious to create and enter passcodes. In order to make the passcode both secure and easy to use, it must be modified to the required security level.