Transport of sulfonium compounds. Characterization of the s-adenosylmethionine and s-methylmethionine permeases from the yeast Saccharomyces cerevisiae.
We report here the characterization and the molecular analysis of the two high affinity permeases that mediate the transport of S-adenosylmethionine (AdoMet) and S-methylmethionine (SMM) across the plasma membrane of yeast cells. Mutant cells unable to use AdoMet as a sulfur source were first isolated and demonstrated to lack high affinity AdoMet transport capacities. Functional complementation cloning allowed us to identify the corresponding gene (SAM3), which encodes an integral membrane protein comprising 12 putative membrane spanning regions and belonging to the amino acid permease family. Among amino acid permease members, the closest relative of Sam3p is encoded by the YLL061w open reading frame. Disruption of YLL061w was shown to specifically lead to cells unable to use SMM as a sulfur source. Accordingly, transport assays demonstrated that YLL061w disruption mutation impaired the high affinity SMM permease, and YLL061w was therefore renamed MMP1. Further study of sam3Delta and mmp1Delta mutant cells showed that in addition to high affinity permeases, both sulfonium compounds are transported into yeast cells by low affinity transport systems that appear to be carrier-facilitated diffusion.
Rouillon
A
A
Centre de Génétique Moléculaire, CNRS, 91198 Gif-sur-Yvette, France.
Surdin-Kerjan
Y
Y
Thomas
D
D
D000595:Amino Acid Sequence; D026905:Amino Acid Transport Systems; D001692:Biological Transport; D003001:Cloning, Molecular; D004058:Diffusion; D029968:Escherichia coli Proteins; D005656:Fungal Proteins; D026901:Membrane Transport Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D012436:S-Adenosylmethionine / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity; D013452:Sulfonium Compounds / Q000378:metabolism*
D026905:Amino Acid Transport Systems; D029968:Escherichia coli Proteins; D005656:Fungal Proteins; D026901:Membrane Transport Proteins; C429746:SAM3 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D013452:Sulfonium Compounds; C117106:mmuP protein, E coli; C429724:ykfD protein, E coli; D012436:S-Adenosylmethionine