The gluEMP operon from Zymomonas mobilis encodes a high-affinity glutamate carrier with similarity to binding-protein-dependent transport systems.
The nucleotide sequence downstream of the grp gene, encoding the glutamate uptake regulatory protein of Zymomonas mobilis, was determined. Three clustered genes (gluE, gluM, and gluP) close to ghe grp gene, but on the opposite strand, were identified. These genes encode a high-affinity transport system for glutamate and aspartate. The gluP gene product is a polypeptide of 25.4 kDa and contains segments with significant similarity to the ATP-binding proteins of binding-protein-dependent transport systems. The GluM polypeptide (22.9 kDa) is highly hydrophobic and consists of four potential membrane-spanning domains. The hydrophilic gluE gene product, with a molecular mass of 22.1 kDa, contains a region with sequence similarity to some of the periplasmic binding proteins and a sequence motif of a signal peptide for periplasmic localization. The transport system could not be functionally expressed in Z. mobilis. However, when heterologously expressed in Escherichia coli, it catalyzed uptake of glutamate, which was characterized kinetically. Our results suggest that the glutamate transport system encoded by the gluEMP operon is repressed in Z. mobilis by the regulatory protein Grp.
Peekhaus
N
N
Institut für Biotechnologie I, Forschungszentrum Jülich GmbH, Germany. peekhaus.1@osu.edu
Krämer
R
R
D018528:ATP-Binding Cassette Transporters / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics*; D000595:Amino Acid Sequence; D027322:Amino Acid Transport System X-AG; D001224:Aspartic Acid / Q000378:metabolism; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics*; D001483:Base Sequence; D001692:Biological Transport; D003001:Cloning, Molecular; D017124:Conserved Sequence; D004268:DNA-Binding Proteins / Q000502:physiology*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D005971:Glutamates / Q000378:metabolism; D008969:Molecular Sequence Data; D005810:Multigene Family; D016366:Open Reading Frames / Q000235:genetics; D009876:Operon / Q000235:genetics*; D011994:Recombinant Proteins / Q000096:biosynthesis; D014157:Transcription Factors / Q000502:physiology*; D017355:Zymomonas / Q000235:genetics* / Q000378:metabolism
D018528:ATP-Binding Cassette Transporters; D027322:Amino Acid Transport System X-AG; D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D005971:Glutamates; C095470:Grp protein, Zymomonas mobilis; D011994:Recombinant Proteins; D014157:Transcription Factors; D001224:Aspartic Acid