@article{mbs:/content/journal/micro/10.1099/00221287-130-8-1961, author = "Glenn, A. R. and Dilworth, M. J.", title = "Methylamine and Ammonium Transport Systems in Rhizobium leguminosarum MNF3841", journal= "Microbiology", year = "1984", volume = "130", number = "8", pages = "1961-1968", doi = "https://doi.org/10.1099/00221287-130-8-1961", url = "https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-130-8-1961", publisher = "Microbiology Society", issn = "1465-2080", type = "Journal Article", abstract = "As the sole source of nitrogen, methylamine supported the growth of a range of species of Rhizobium. The methylamine assimilatory system was inducible in R. leguminosarum MNF3841, whereas the capacity to utilize NH4 + as a nitrogen source was constitutive. An uptake system for [14C]methylamine (methylamine permease) was induced by growth of MNF3841 on methylamine or ethylamine. The uptake was sensitive to 2,4-dinitrophenol, azide and carbonyl cyanide m-chlorophenylhydrazone. The methylamine permease had a K m of 0·035 mm, a V max of 2·2 nmol min−1 (mg protein)−1 and a K i for ammonium of 1·5 mm. Most of the [14C]methylamine accumulated by cells was rapidly incorporated into TCA-insoluble materials. An NH4 +-sensitive methylamine-accumulating system distinct from the methylamine permease was demonstrated in ammonia-limited cells grown in continuous culture. This system, the ammonium permease, had a K m of 0·11 mm (for methylamine), a K i for NH4 + of 0·007 mm and a V max, of 2·5 nmol min−1 (mg protein)−1. Methylamine was accumulated by chemostat-grown, N-limited cells and could exchange with unlabelled methylamine. Treatment with carbonyl cyanide m-chlorophenylhydrazone caused efflux of the accumulated methylamine, whereas high concentrations of NH4 + did not. Thus R. leguminosarum possesses a specific methylamine permease which is quite distinct from the ammonium permease.", }