RECA PROTEIN PROMOTES RAPID RNA-DNA HYBRIDIZATION IN HETEROGENEOUS RNA MIXTURES

The nucleoprotein filament formed by the RecA protein of Escherichia coli on single-stranded DNA catalyzes the hybridization of RNA transcripts with single-stranded DNA sequences at 37-degrees-C, in vitro. RecA protein rapidly promotes hybridization, even when noncomplementary RNA is in a millionfold nucleotide excess over hybridizing RNA, and in a thousandfold nucleotide excess over hybridizing single-stranded DNA. Heterologous double-stranded DNA and RecA-coated noncomplementary single-stranded DNA are also poor competitors of RNA transcripts produced in vitro . Since large excesses of noncomplementary RNA fail to inhibit sharply the hybridization reaction by RecA protein under mild, non-degradative conditions, the reaction may be useful in the identification and isolation of transcripts produced in vivo.