Disease relevance of nodA

• We have analysed the metabolites which are produced in vivo and in vitro by Rhizobium strains which express the single nodA, nodB and nodC genes or combinations of the three [1].
• Further analysis revealed that the Bradyrhizobium sp. ANU289 NodA is active in the biosynthesis of LCOs, but is unable to direct the transfer of the R. l. by, viciae nodFE-dependent multi-unsaturated fatty acid to the chitin oligosaccharide acceptor [2].
• Evidence that the protein that binds to the regulatory sequences is the nodD gene product came from the observation that a complex was formed between the nod box preceding nodA and protein from a cell-free extract isolated from Escherichia coli containing the cloned nodD gene [3].
• Three phylogenetic groups of nodA and nifH genes in Sinorhizobium and Mesorhizobium isolates from leguminous trees growing in Africa and Latin America [4].
• Plant tests and nodA amplification assays showed that "M. nodulans" is the only nodulating Methylobacterium sp. identified so far [5].

High impact information on nodA

• These results confirm previous reports that NodB is an N-deacetylase and suggest that NodA is an N-acyltransferase [6].
• Acylation of this oligosaccharide required only NodA [6].
• To elucidate the role of the NodA protein in lipooligosaccharide biosynthesis, we prepared a radiolabeled tetrasaccharide precursor carrying an amino group as a potential attachment site for N-acylation at the nonreducing glucosamine residue [7].
• Further studies of NodD production and nod genes-lacZ fusions expression in the hurL mutant revealed that inactivation of hurL led to severe impairment in the nodD expression, repression in the inducible expression of nodA and nodF, and slight enhancement in the expression of px2, a gene identified earlier in this lab [8].
• Upstream of nodA and nodF is a conserved sequence, the nod box, which has been implicated in nodD-mediated transcriptional activation of these genes [3].

Biological context of nodA

• The 9.2-kb fragment complemented nodA-, nodB-, and nodC- mutants of R. meliloti to the Nod+ phenotype on Medicago sativa, M. truncatula, and Trigonella foenum-graecum [9].
• The presence of nodA in the nodABCIJ operon makes genetic studies difficult to interpret [2].
• The NodBCS metabolites were partially converted to lipo-chitooligosaccharides when the nodABCS genes were expressed, showing that NodA was involved in the acylation and acted after NodS [10].
• A series of repetitive sequences responsible for this hybridization lies within a 0.95-kb HindIII/SalI subfragment about 1-kb upstream of nodA [11].
• Both NodC and NodA were detected in the cytoplasm and cell envelope in thin sections of free-living rhizobia treated with luteolin, a known inducer of nod gene expression; however, only NodC was detected on cell surfaces when immunolabeling was performed with intact induced cells [12].

Anatomical context of nodA

• The induction of the nodA promoter by root exudate and by the most effective inducer naringenin was very similar, as judged from the genetic requirements and the kinetics of induction [13].

Associations of nodA with chemical compounds

• Analysis of GlcNAc metabolites from various mutants, e.g., nodA-, nodB-, or nodC- mutants, should facilitate the identification of the in vivo substrates involved in the synthesis of the "common" Nod factor and, thereby, lead to a greater understanding of Nod factor biosynthesis and transport [14].
• Genes encoding two key enzymes of methylotrophy and nodulation, the mxaF gene, encoding the alpha subunit of the methanol dehydrogenase, and the nodA gene, encoding an acyltransferase involved in Nod factor biosynthesis, were sequenced for the type strain, ORS2060 [5].

Other interactions of nodA

• The predicted nodA and nodB genes overlap by four nucleotides and the nod F and nodE genes overlap by a single nucleotide, suggesting that translational coupling may ensure the synthesis of equimolar amounts of these gene products [15].
• However, a subcloned fragment containing only the nodC gene did not induce normal root hair curling (although some branching was observed), indicating that the nodA and B genes may also be required for normal root hair curling [16].
• The open reading frame identified between nodD1 and nodA in the B. elkanii sequence was far more similar to nodK from Bradyrhizobium sp. (Parasponia) than to nodY from B. japonicum [17].

Analytical, diagnostic and therapeutic context of nodA

• The restriction patterns and a sequence analysis of the nodA and nifH genes divided the strains into the following three distinct groups: sinorhizobia from Africa, sinorhizobia from Latin America, and mesorhizobia from both regions [4].
• These strains did not induce any nodule formation when inoculated on the wide host spectrum legume species M. atropurpureum (Siratro) and no nodA gene could be amplified by PCR [18].

References