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The NodI and NodJ proteins from Rhizobium and Bradyrhizobium strains are similar to capsular polysaccharide secretion proteins from Gram‐negative bacteria

1993; Wiley; Volume: 8; Issue: 2 Linguagem: Inglês

10.1111/j.1365-2958.1993.tb01580.x

1365-2958

Martha Vâzquez, Olivia Santana, Carmen Quinto,

Plant nutrient uptake and metabolism

Summary The NodI and NodJ nodulation proteins have been described in different Rhizobium and Bradyrhizobium species. The NodIJ genes belong to the nod regulon. Other genes from this regulon are involved in the biosynthesis and modification of lipo‐oligosaccharide molecule(s) which are morphogénic signals when acting on legume roots. It has been proposed that the NodI and NodJ proteins belong to a bacterial inner membrane transport system of small molecules. Nucleotide sequencing of MudII PR 13 insertions in the nodulation region of the symbiotic plasmid from a Rhizobium leguminosarum bv. phaseoli strain CE3 has revealed the presence of NodI and nodJ related sequences downstream of nodC. Computer nucleotide sequence analysis of the entire NodI and NodJ sequences from R. leguminosarum bv. viciae and Bradyrhizobium japonicum strains show that both proteins are similar to the KpsT and KpsM proteins from Escherichia coli Kl and K5 strains, to the BexB and BexA proteins from Haemophilis influenzae and to the CtrD and CtrC proteins from Neisseria meningitidis , respectively. Except for the NodI and NodJ proteins, all of them have been involved in the mechanism of secretion of polysaccharides in each of their harbouring species. On the basis of the similarity found, we propose that the NodI and the NodJ proteins could be involved in the export of a lipo‐oligosaccharide.