Zeatin ribonucleosides in the transfer ribonucleic acid of Rhizobium leguminosarum, Agrobacterium tumefaciens, Corynebacterium fascians, and Erwinia amylovora

Abstract

Until recently, the presence in transfer ribonucleic acid (tRNA) ofthe hydroxylated cytokinin ribosylzeatin [N6-(4-hydroxy-3-methylbut-2-enyl)adenosine] was thought to be unique to higher plants. This extension of work from several laboratories indicates the presence of 2-methylthioribosylzeatin in the tRNA of the plant-associated bacteria Rhizobium leguminosarum, Agrobacterium tumefaciens, and Corynebacterium fascians, but not in that of Erwinia amylovora. This cytokinin has the cis configuration, as is normally found in the tRNA's of plants. The tRNA thionucleotide patterns in these bacteria are different from those of Escherichia coli, Bacillus subtilis, and Salmonella typhimurium, which contain the unhydroxylated analogs of ribosylzeatin or 2-methylthioribosylzeatin.

Presence of 2-methylthioribosyl-trans-zeatin in Azotobacter vinelandii tRNA

“…The experiments presented here clearly establish the presence of trans-ms2iO6A in the tRNA of A. vinelandii. The tRNAs of bacteria such as R. leguminosarum, A. tumefaciens, and Pseudomonas aeruginosa have been reported to contain the cis isomer of ms2iO6A (13,14,33). Thus, the presence of the trans isomer in A. vinelandii tRNA is a new finding.…”

“…Therefore, it has been suggested that only plants have the gene for the hydroxylating enzyme which converts i6A and ms2i6A to the respective hydroxylated derivatives iO6A and ms2iO6A (32). Bacteria such as Rhizobium leguminosarum, Agrobacterium tumefaciens, and Corynebacterium fascians have been shown to contain iO6A or ms2iO6A in their tRNA (12)(13)(14)23). This indicated the presence of hydroxylase, implying that these bacteria acquired the gene for the hydroxylase activity from the plants during their association over long periods of time (12,13).…”

“…Bacteria such as Rhizobium leguminosarum, Agrobacterium tumefaciens, and Corynebacterium fascians have been shown to contain iO6A or ms2iO6A in their tRNA (12)(13)(14)23). This indicated the presence of hydroxylase, implying that these bacteria acquired the gene for the hydroxylase activity from the plants during their association over long periods of time (12,13). In this paper we establish the presence of trans-ms2iO6A in the tRNA of Azotobacter vinelandii, a free-living, nitrogen-fixing bacterium found in the inner rhizosphere of plant roots.…”

Cytokinin biosynthesis and interconversion

“…666 Physiol, Plant, 101, 1997 Once the adenosine residue has been isopentenylated, it may be further modified by side chain hydroxylation and/or ring methylation to give cytokinin derivatives such as c/5-ribosylzeatin or 2-methylthioribosylzeatin (Cherayil and Lipsett 1977).…”

Cloning and nucleotide sequence of thetzsgene fromAgrobacterium tumefaciensstrain T37

“…While T-DNA phytohormone genes are expressed in crown gall tumors, other phytohormone-related loci are expressed in A. tumefaciens. The bacterium produces both auxins (23)(24)(25)(26) and cytokinins (27)(28)(29)(30)(31)(32)(33)(34). The production of auxins by strain C58 has been reported to involve two genetic loci, one chromosomal (iaaC) and one plasmid-borne (iaaP) (26).…”