Disease relevance of nodD2

• nodD2 of Rhizobium sp. NGR234 is involved in the repression of the nodABC operon [1].
• The predicted NodD1 and NodD2 proteins shared 62% identical amino acid residues at corresponding positions and exhibited different degrees of homology with NodD proteins of other Bradyrhizobium, Azorhizobium, and Rhizobium strains [2].

High impact information on nodD2

• Activation of transcription of nodD2 is also dependent on flavonoids despite the absence of a nod-box like sequence in the upstream promoter region [3].
• Thus, NodD1, NodD2 and SyrM2 co-modulate a flavonoid-inducible regulatory cascade that coordinates the expression of symbiotic genes with nodule development [3].
• In turn, NodD2 is involved in the repression of the NB8 nodABCIJnolOnoeI operon [3].
• Mutational analysis showed that syrM 2 (another member of the LysR family), which is controlled by NB19, is also necessary for expression of nodD 2 [3].
• This mutant (NGR omega nodD2) was deficient in nitrogen fixation on Vigna unguiculata and induced pseudonodules on Tephrosia vogelii [1].

Chemical compound and disease context of nodD2

• Nine flavonoid aglycones released from black bean (Phaseolus vulgaris 'PI165426CS') seeds and roots induced nodC::lacZ transcription in Rhizobium leguminosarum bv. phaseoli strains containing extra cloned copies of the regulatory genes nodD1, nodD2, or nodD3 from that biovar [4].
• Flavonoids, NodD1, NodD2, and nod-box NB15 modulate expression of the y4wEFG locus that is required for indole-3-acetic acid synthesis in Rhizobium sp. strain NGR234 [5].

Biological context of nodD2

• Part of the extremely broad host range of NGR234 can be attributed to nodD1, although the second gene shares a high degree of DNA sequence homology with nodD2 of R. fredii USDA191 [1].
• A nodD2 mutant of NGR234 was constructed by insertional mutagenesis [1].
• Competitive RNA hybridizations, gene fusions and mobility shift assays confirmed that nodD2 downregulates expression of the nodABC operon [1].
• The promoter activity of NB15 and IAA production both were enhanced by introduction of a multicopy plasmid carrying nodD2 into NGR234 [5].
• Analysis of the sequence showed open reading frames highly homologous to nolA, nodD2, nodD1, and nodKABC from other bradyrhizobial sources [6].

Anatomical context of nodD2

• Transcription of nodD2 and nodD3 was constitutive. nodC of R. leguminosarum biovar phaseoli was activated by each of the nodD genes of that biovar in the absence of inducers but expression was enhanced in cells grown with bean exudate or the flavonoids genistein or naringenin [7].

Associations of nodD2 with chemical compounds

• While mixtures of the methoxychalcone and luteolin showed a positive synergism with extra NodD1 protein, they apparently competed for binding to the NodD2 protein [8].
• The production of IAA is increased strongly by exposure of NGR234 to daidzein in a NodD1-, NodD2-, and SyrM2-dependent manner [5].

Other interactions of nodD2

• Induction of the nodYABCSUIJ operon, as measured by expression of a translational nodC'-'lacZ fusion, required the nodD1 gene, but not nodD2 [2].

Analytical, diagnostic and therapeutic context of nodD2

• Seventy-three isolates of rhizobia sampled from root nodules of Medicago truncatula were analyzed by restriction fragment length polymorphism (RFLP) of DNA regions amplified by the polymerase chain reaction (PCR) targeting the symbiotic plasmid (nifD-K, nodD1, and nodD2 genes) and the chromosome (16S rDNA plus intergenic spacer) [9].

References