Fecha de publicación: 05/01/2023 Fuente: WIPO Rice Provided are novel CRISPR/Cas compositions and uses thereof for targeting nucleic acids. In particular, non-naturally occurring or engineered RNA-targeting systems comprising a novel RNA-targeting Cas13c, Cas13d, Cas13e, or Cas13f effector protein, and at least one targeting nucleic acid component such as a guide RNA (gRNA) or crRNA are provided. The novel Cas effector proteins are among the smallest of the known Cas effector proteins, at about 800-900 amino acids in size, and are thus uniquely suitable for delivery using vectors of small capacity, such as an AAV vector.