Abstract: External guide sequences ("EGS") can be used to promote RNAase P-mediated cleavage of RNA transcribed from plasmids and other genetic elements which confer drug resistance on bacterial cells. Such cleavage can render the bacteria drug sensitive. In a preferred embodiment, a vector encoding an EGS is administered to an animal or human harboring antibiotic resistant bacterial cells such that the EGS is expressed in the bacterial cells, the EGS promotes RNAase P-mediated cleavage of RNA involved in conferring antibiotic resistance to the cells, and the cells are rendered antibiotic sensitive. A preferred form of administration is via inoculation of the animal or human with cells containing genes for appropriate EGSs on promiscuous plasmids. These plasmids will spread quickly through the antibiotic-resistant population of bacterial cells, thereby making the cells susceptible to antibiotic therapy.

Abstract: It has been discovered that any RNA can be targeted for cleavage by RNase P from prokaryotic or eukaryotic cells using a suitably designed oligonucleotide ("external guide sequence", or EGS) to form a hybrid with the target RNA, thereby creating a substrate for cleavage by RNase P in vitro. The EGS hydrogen bonds to the targeted RNA to form a partial tRNA like structure including the aminoacyl acceptor stem, the T stem and loop, and part of the D stem. An EGS can be modified both by changes in sequence and by chemical modifications to the nucleotides. The EGS can be a separate molecule or can be combined with an RNase P catalytic RNA sequence to form a single oligonucleotide molecule ("RNase P internal guide sequence" or RIGS). Methods are also disclosed to randomly select and to express a suitable EGS or RIGS in vivo to make a selected RNA a target for cleavage by a host cell RNase P or introduced RIGS, thus preventing expression of the function of the target RNA.

Abstract: It has been discovered that any RNA can be targeted for cleavage by RNAase P from eukaryotic cells, for example, human RNAase P, using a suitably designed oligoribonucleotide ("external guide sequence", or EGS) to form a hybrid with the target RNA, thereby creating a substrate for cleavage by RNAase P in vitro. The EGS hydrogen bonds to the targeted RNA to form a partial tRNA like structure including the aminoacyl acceptor stem, the T stem and loop, and part of the D stem. The most efficient EGS with human RNAase P is the EGS in which the anticodon stem and loop was deleted. Modifications can also be made within the T-loop. Methods are also disclosed to randomly select and to express a suitable EGS in vivo to make a selected RNA a target for cleavage by the host cell RNAase P, thus preventing expression of the function of the target RNA. The methods and compositions should be useful to prevent the expression of disease-causing genes in vivo.

Abstract: It has been discovered that any RNA can be targeted for cleavage by RNAase P from eukaryotic cells, for example, human RNAase P, using a suitably designed oligoribonucleotide ("external guide sequence", or EGS) to form a hybrid with the target RNA, thereby creating a substrate for cleavage by RNAase P in vitro. The EGS hydrogen bonds to the targeted RNA to form a partial tRNA like structure including the aminoacyl acceptor stem, the T stem and loop, and part of the D stem. The most efficient EGS with human RNAase P is the EGS in which the anticodon stem and loop was deleted. Modifications can also be made within the T-loop. Methods are also disclosed to randomly select and to express a suitable EGS in vivo to make a selected RNA a target for cleavage by the host cell RNAase P, thus preventing expression of the function of the target RNA. The methods and compositions should be useful to prevent the expression of disease-causing genes in vivo.