Disease relevance of Octopine

• The A6S/2 tumor incited on tobacco by Agrobacterium tumefaciens harboring the octopine-type A6 Ti plasmid contains one insert of Ti-plasmid sequences (the T DNA) [1].
• In a first set of experiments, gene 4 from octopine plasmid pTiAch5 and nopaline plasmid pTiC58 was expressed in Escherichia coli, and the gene products were identified by reaction with antiserum raised against a decapeptide derived from the DNA sequence of the gene [2].
• No CAT enzyme activity could be detected in transgenic tobacco plants unless upstream promoter elements from the octopine synthase gene or the cauliflower mosaic virus 35S promoter were supplied in addition to the maize promoter region [3].
• The TraR-activated promoter lies just downstream from the octopine catabolic genes, and transcribes six genes in addition to traR, including five genes (ophABCDE) that show strong homology to oligo-peptide permeases of Salmonella typhimurium and Bacillus subtilis [4].
• The host range of an octopine Ti plasmid is limited to Rhizobiaceae [5].

High impact information on Octopine

• Octopine is released from crown gall tumors as a nutrient source and a signal molecule for the plant pathogen Agrobacterium tumefaciens [6].
• The continued presence of T-DNA sequences in shoots is directly demonstrated by Southern blotting and is also revealed by the presence of the tumor markers octopine and nopaline [7].
• Mutation of the virF gene leads to a weakened virulence of octopine strains on tomato and Nicotiana glauca (shrub tobacco) [8].
• Although promoter regions for many plant nuclear genes have been sequenced, identification of the active promoter sequence has been carried out only for the octopine synthase promoter [9].
• Octopine as an end product of anaerobic glycolysis in the chambered nautilus [10].

Chemical compound and disease context of Octopine

• We have generated mutations in the promoter region of the octopine type cytokinin gene of Agrobacterium tumefaciens, and studied their effects on mRNA formation in different plant species [11].
• Conjugation of Agrobacterium tumefaciens wide-host-range octopine-type Ti plasmids is regulated by the LuxR-type transcriptional activator TraR in conjunction with an acylated homoserine lactone designated AAI [4].
• A novel methionine-containing plasmid-determined compound, N2-(1-carboxyethyl)methionine (NCEM) has been identified in crown-gall tumours induced by octopine-type strains of Agrobacterium tumefaciens [12].
• Octopine-type strains of Agrobacterium tumefaciens degrade the opine mannopinic acid through a specific pathway which involves cleavage of the molecule at the C--N bond between the amino acid and the sugar moieties [13].
• To explore the possibility of palatinose production in plants a recently isolated sucrose isomerase gene (palI; EC 5.4.99.11) from Erwinia rhapontici [F. Börnke et al. (2001) J Bacteriol 183: 2425-2430] was cloned into a plant expression vector between the constitutive 35S CaMV promoter and the octopine synthase polyadenylation signal [14].

Biological context of Octopine

• The observed variation in the organization of T-DNA in octopine crown gall tissue did not appear to be a characteristic of the way the tissue was derived [15].
• Vir regions from different Ti plasmids may vary slightly in the genes they contain: for instance, the virF gene, which is present in the Vir-region of octopine Ti plasmids, is absent from nopaline Ti plasmids [8].
• Promoter DNA sequences from a petunia chlorophyll a/b binding protein gene were fused to octopine synthase DNA sequences and the resulting chimaeric genes were introduced into petunia and tobacco cells [16].
• Sequences in the 3'-untranslated region of two different octopine T-DNA genes were analyzed with regard to their significance in polyadenylation [17].
• These regions code for octopine catabolism, virulence and plant tumor phenotype [18].

Anatomical context of Octopine

• Octopine-type tumor tissue was obtained both by infection of plants or isolated protoplasts with Agrobacterium tumefaciens and by somatic hybridization of normal and crown gall tobacco cells [15].
• The 5'- terminus of the polyadenylated tmr mRNA isolated from octopine tobacco tumor cell lines was determined by nuclease S1 mapping [19].
• The octopine T-DNA organisation in the cell nucleus is significantly different from that of nopaline T-DNAs: tandem arrangements of T-DNA segments could not be detected and the T-DNA itself is much shorter [20].
• Cloned DNA injected into oocytes consisted of T-DNA sequences derived from octopine type Ti plasmid B6-806 and T-DNA attached to plant DNA sequences at the left junction in crown gall tumors [21].

Associations of Octopine with other chemical compounds

• Octopine-type virA mutant strains that express vir genes at high levels in the absence of the plant inducing compound acetosyringone also efficiently transferred MSV DNA [22].
• The Saccharomyces cerevisiae ILV1 gene, encoding threonine dehydratase (EC 4.2.1.16) was fused to the transferred DNA nopaline synthase promoter and the 3' noncoding region of the octopine synthase gene [23].
• Mannopinic acid and agropinic acid catabolism region of the octopine-type Ti plasmid pTi15955 [24].
• The Mr 18.000 protein represented a fusion product between chloramphenicol acetyltransferase (CAT) on pACYC184 and a part of lysopine dehydrogenase (LpDH), the enzyme synthesizing octopine and lysopine in plant tumor cells [25].
• We measured the transient fluorescence of NADH bound to octopine dehydrogenase in the binary octopine dehydrogenase-NADH complex and in the ternary complexes containing D-octopine, L-allooctopine, L-arginine, D-arginine, or 5-guanidinovaleric acid [26].

Gene context of Octopine

• It contains an open reading frame (ORF) of 759 nucleotides and has 77% homology to the virG sequences of octopine type plasmids [27].
• High nucleotide and amino acid sequence homologies were observed between pTiC58 virA and the virA sequences of three octopine-type plasmids [28].
• Comparative nucleotide sequence analyses of virD2 showed that the first 684 bp were 81% homologous to virD2 of an octopine Ti plasmid whereas the remaining 660 bp were only 44% homologous [29].
• The complete nucleotide sequence of the virB locus, from the octopine Ti plasmid of Agrobacterium tumefaciens strain 15955, has been determined [30].
• In the present study, we have identified a fourth gene (repD) in the repABC operon of an octopine-type Ti plasmid. repD is 78 codons in length, and maps between repA and repB genes [31].

Analytical, diagnostic and therapeutic context of Octopine

• We have used DNA microarrays, representing all genes of the octopine- and nopaline-type Ti plasmids, to identify all Ti-plasmid-encoded genes in the vir regulons of both plasmids [32].
• Sequence analysis shows that the limited and wide host range biotype III OC TA regions are derived from a common ancestor structure which lacked the 6a gene found in the biotype I octopine TL region [33].
• Restriction enzyme analysis of the Ti plasmid from strain 89.10, an octopine strain that is naturally unable to utilize mannopinic acid, showed a deletion in this same region encoding the specific mannopinic acid degradation pathway [13].
• We used this technique to introduce chromosomal DNA into recipient A. tumefaciens strains by electroporation and constructed isogenic chvE mutants that share the same chromosomal background but differ in their types of pTi (octopine or nopaline) [34].
• By using bidimensional chromatography followed by autoradiography, very small amounts of octopine can be clearly detected in tumors grown in vitro [35].

References