RT Journal Article SR Electronic(1) A1 Glenn, A. R. A1 Dilworth, M. J.YR 1984 T1 Methylamine and Ammonium Transport Systems in Rhizobium leguminosarum MNF3841 JF Microbiology, VO 130 IS 8 SP 1961 OP 1968 DO https://doi.org/10.1099/00221287-130-8-1961 PB Microbiology Society, SN 1465-2080, AB 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., UL https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-130-8-1961