The present invention is directed to methods and compositions for targeted gene silencing that provide the ability to not only repress expression but to modulate the repression of expression of one or more target genes. In one aspect, a recombinant nucleic acid molecule is provided comprising a nucleotide sequence encoding a subset of CRISPR-cas polypeptides, or functional fragments thereof, from a type-l CRISPR-cas system. In some aspects, a recombinante nucleic acid of the invention comprises a nucleotide sequence encoding three or more Type I Cascade polypeptides having substantial identity to a type I Cascade polypeptide.
