Genetic targeting in non-conventional yeast using an RNA-guided endonuclease
Non-conventional yeasts are disclosed herein comprising at least one RNA-guided endonuclease (RGEN) comprising at least one RNA component that does not have a 5′-cap. This uncapped RNA component comprises a sequence complementary to a target site sequence in a chromosome or episome in the yeast. The RGEN can bind to, and optionally cleave, one or both DNA strands at the target site sequence. An example of an RGEN herein is a complex of a Cas9 protein with a guide RNA. A ribozyme is used in certain embodiments to provide an RNA component lacking a 5′-cap. Further disclosed are methods of genetic targeting in non-conventional yeast.
1. A non-conventional yeast comprising a Cas endonuclease and a polynucleotide sequence, wherein said polynucleotide sequence comprises an RNA polymerase (II) promoter operably linked to a first DNA sequence encoding a ribozyme and a second DNA sequence encoding an RNA component, wherein said first DNA sequence is located 5′ (upstream) of said second DNA sequence, and wherein said polynucleotide sequence does not comprise a third DNA sequence encoding a ribozyme located 3′ (downstream) from the second DNA sequence, wherein said RNA component comprises a variable targeting domain complementary to a target site sequence on a chromosome or episome in the yeast, and wherein the RNA component and the Cas endonuclease can form a RNA-guided endonuclease (RGEN), wherein said RGEN can bind to the target site sequence.
2. The non-conventional yeast of claim 1 , wherein the RGEN can bind to and cleave the target site sequence.
3. The non-conventional yeast of claim 1 , wherein said yeast is a member of a genus selected from the group consisting of Yarrowia, Pichia, Schwanniomyces, Kluyveromyces, Arxula, Trichosporon, Candida, Ustilago, Torulopsis, Zygosaccharomyces, Trigonopsis, Cryptococcus, Rhodotorula, Phaffia, Sporobolomyces , and Pachysolen.
4. The non-conventional yeast of any one of claims 1 to 3 , wherein the RGEN comprises a CRISPR (clustered regularly interspaced short palindromic repeats)-associated (Cas) protein-9 (Cas9) amino acid sequence.
5. The non-conventional yeast of any one of claims 1 to 3 , wherein the RNA transcribed from the nucleotide sequence autocatalytically removes the ribozyme to yield said RNA component, wherein said RNA component does not have a 5′ cap.
6. The non-conventional yeast of claim 5 , wherein the ribozyme is a hammerhead ribozyme, hepatitis delta virus ribozyme, group I intron ribozyme, RnaseP ribozyme, or hairpin ribozyme.
7. The non-conventional yeast of any one of claims 1 to 3 , wherein the RNA transcribed from the nucleotide sequence does not autocatalytically remove the ribozyme, wherein said ribozyme cleaves any RNA sequence 5′ of itself and yields a ribozyme-RNA component fusion molecule without a 5′ cap.
8. A method for modifying a target site on a chromosome or episome in a non-conventional yeast, the method comprising providing to a non-conventional yeast a first recombinant DNA construct comprising a DNA sequence encoding a Cas endonuclease, and a second recombinant DNA construct comprising an RNA polymerase (II) promoter operably linked to a DNA sequence encoding a ribozyme upstream of an RNA component, wherein the second recombinant DNA construct does not comprise a ribozyme sequence located downstream from the ribozyme-RNA component, wherein the RNA transcribed from the second recombinant DNA construct autocatalytically removes the ribozyme to yield said RNA component, wherein the Cas endonuclease introduces a single or double-strand break at said target site.
9. The method of claim 8 , further comprising identifying at least one non-conventional yeast cell that has a modification at said target, wherein the modification includes at least one deletion, addition or substitution of one or more nucleotides in said target site.
10. The method of claim 8 , further comprising providing a donor DNA to said yeast, wherein said donor DNA comprises a polynucleotide of interest.
11. The method of claim 9 , further comprising identifying at least one yeast cell comprising in its chromosome or episome the polynucleotide of interest integrated at said target site.