Nucleotide sequence of the Agrobacterium tumefaciens octopine Ti plasmld-encoded tmr gene

Abstract

The nucleotide sequence of the tmr gene, encoded by the octopine Ti plasmid from Agrobacteriumtumefaciens (pTiAch5), was determined. The T-DNA, which encompasses this gene, is Involved in tumor formation and maintenance, and probably mediates the cytokinin-independent growth of transformed plant cells. The nucleotide sequence of the tmr gene displays a continuous open reading frame specifying a polypeptide chain of 240 amino acids. The 5′- terminus of the polyadenylated tmr mRNA isolated from octopine tobacco tumor cell lines was determined by nuclease SI mapping. The nucleotide sequence 5′-TATAAAA-3′, which sequence is Identical to the canonical “TATA” box, was found 29 nucleotides upstream from the major initiation site for RNA synthesis. Two potential poly-adenylatlon signals 5′-AATAAA-3′ were found at 207 and 275 nucleotides downstream from the TAG stopcodon of the tmr gene. A comparison was made of nucleotide stretches, involved in transcription control of T-DNA genes.