EXAMINATION OF PUTATIVE METHYLAMINE PERMEASE GENES IN <I>Methanosarcina acetivorans</I> C2A.

Methanosarcina acetivorans is a methanogenic archaeon capable of utilizing monomethylamine (MMA), dimethylamine (DMA) and trimethylamine (TMA) for methanogenesis. The mtmP, mtbP, mttP1 and mttP2 genes were predicted to encode MMA, DMA, TMA and TMA permeases, respectively, based on their genomic context and bioinformatic analysis. We investigated the roles of these predicted permeases in growth on methylamines. The ΔmtmP, ΔmtbP, and ΔmttP1/ΔmttP2 deletion strains were created using a markerless genetic exchange method. Unaltered growth phenotypes of the mutants on their respective methylamines, except for an extended lag phase in the ΔmtmP mutant, suggest the respective substrates are still transported in the absence of the predicted permeases. These results could be due to broad substrate specificity of the permeases or due to alternative permease activity when grown in pure culture under laboratory conditions of substrate concentration. The ΔmtmP/ΔmtbP and ΔmtbP/ΔmttP1/ΔmttP2 deletion strains show some defect in DMA-dependent growth suggesting cross-reactivity between methylamine permeases.