Arbor launches with $15.6 million, new CRISPR enzyme

Arbor Biotechnologies Inc. (Cambridge, Mass.) emerged from stealth mode on Thursday with a study detailing the discovery of a new CRISPR enzyme, CRISPR-associated protein 13d (Cas13d), and a $15.6 million series A round that closed last June. Investors included Arch Venture Partners, Faridan, Alexandria Real Estate Equities and private investors.

Launched in 2016 by co-founders including CRISPR pioneer Feng Zhang and Illumina Inc. (NASDAQ:ILMN) and Quanterix Corp. (NASDAQ:QTRX) co-founder David Walt, Arbor has a genome screening platform to identify new natural proteins and peptides with potential medical, agricultural and industrial applications. The platform combines a set of AI, genome sequencing, gene synthesis and high-throughput screening technologies.

Arbor's first application of the platform is to mine the prokaryotic and metagenomic diversity for new CRISPR-associated enzymes and systems.

In a paper published in Molecular Cell on Thursday, company researchers showed that by relaxing some of the normal search constraints, such as protein size limits, the group was able to identify a new CRISPR enzyme and associated accessory proteins with potential for diagnostic and therapeutic applications.

The group identified Cas13d as an enzyme with similar properties as CRISPR-associated protein 13a (Cas13a), which has been proposed as a diagnostic tool by both Zhang as well as Jennifer Doudna from the University of California Berkeley. Both enzymes detect RNA sequences and perform collateral cleavage, meaning that once the target is recognized, the enzyme indiscriminately cuts any RNA it encounters.

Diagnostics can be designed by adding an RNA reporter construct to a biological sample that is cleaved and produces a signal only when the enzyme encounters its intended target.

The differences are that Cas13d is about 20% smaller than Cas13a and has an associated accessory molecule that controls activity levels of multiple Cas13d orthologs.

Arbor hasn't disclosed whether it will pursue therapeutic or diagnostic applications with Cas13d. The company's primary focus is on biodiscovery, and it is looking at a range of business models that will allow it to disseminate resulting discoveries.