Dimerization of Rhizobium meliloti NifH protein in Saccharomyces cerevisiae cells requires simultaneous expression of NifM protein.
Compared to free living diazotrophs, the nitrogenase system of symbiotic microorganisms, like Rhizobium (Synorhizobium) meliloti, was poorly studied. The aim of our research was to investigate whether (by analogy with Klebsiella pneumoniae) the NifM product is required and sufficient to obtain active R. meliloti Fe-protein. We cloned nifH gene of R. meliloti and nifM gene of K. pneumoniae in suitable yeast vectors. When introduced into Saccharomyces cerevisiae cells, both genes were effectively expressed to proteins similar to the native products in its immunoreactivity and apparent molecular mass. The association of R. meliloti NifH protein into dimer structure required co-expression of NifM that also conferred stability of NifH polypeptide. However, the NifH protein synthesized in yeast did not show enzyme activity, suggesting that the NifM of K. pneumoniae is incapable of activating the NifH protein of R. meliloti.
Petrova
Nina
N
Institute of Molecular Biology, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria. npetrova@obzor.bio21.bas.bg
Gigova
Liliana
L
Venkov
Pencho
P
D003001:Cloning, Molecular; D019281:Dimerization; D004795:Enzyme Stability; D015870:Gene Expression; D005798:Genes, Bacterial; D005822:Genetic Vectors; D007711:Klebsiella pneumoniae / Q000201:enzymology / Q000235:genetics; D046911:Macromolecular Substances; D010088:Oxidoreductases / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D014176:Protein Biosynthesis; D012329:RNA, Bacterial / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D016962:Sinorhizobium meliloti / Q000201:enzymology* / Q000235:genetics*
D046911:Macromolecular Substances; D012329:RNA, Bacterial; D012333:RNA, Messenger; D011994:Recombinant Proteins; D010088:Oxidoreductases; C029130:nitrogenase reductase