Functional analysis of multiple nifB genes of Paenibacillus strains in synthesis of Mo-, Fe- and V-nitrogenases

Abstract Background Biological nitrogen fixation is catalyzed by Mo-, V- and Fe-nitrogenases that are encoded nif , vnf anf genes, respectively. NifB the key protein in synthesis of cofactors all nitrogenases. Most diazotrophic Paenibacillus strains have only one nifB gene located a compact cluster ( nifBHDKENX orf1 ) hesAnifV ). But some multiple genes their functions not known. Results A total 138 found 116 strains. Phylogeny analysis shows these fall into 4 classes: I class including (named as nifB1 genes) first within cluster, II nifB2 adjacent to or III whose members designated nifB3 IV named nifB4 scattered on genomes. Functional complementation ? mutant P. polymyxa which has shown both active Mo-nitrogenase, while not. Deletion also revealed sabinae T27 involved Complementation nifBHDK with four reconstituted operons: nifB1anfHDGK nifB2anfHDGK nifB1vnfHDGK nifB2vnfHDGK, were able support Fe- V-nitrogenases. Transcriptional results obtained original consistent results. Conclusions The divided classes. being Fe V-nitrogenases, but system comprising 8 nifBanfHDGK nifXhesAnifV 10 nifBvnfHDGKEN Fe-nitrogenase V-nitrogenase background,