Influence of threonine exporters on threonine production in Escherichia coli.
Threonine production in Escherichia coli threonine producer strains is enhanced by overexpression of the E. coli rhtB and rhtC genes or by heterologous overexpression of the gene encoding the Corynebacterium glutamicum threonine excretion carrier, thrE. Both E. coli genes give rise to a threonine-resistant phenotype when overexpressed, and they decrease the accumulation of radioactive metabolites derived from [(14)C] L-threonine. The evidence presented supports the conclusion that both RhtB and RhtC catalyze efflux of L-threonine and other structurally related neutral amino acids, but that the specificities of these two carriers differ substantially.
Degussa., R & D Feed Additives/Biotechnology, P.O. Box 1112, 33788 Halle, Germany.
D
D
Kruse
R
R
Krämer
L
L
Eggeling
M
M
Rieping
W
W
Pfefferle
J H
JH
Tchieu
Y J
YJ
Chung
M H
MH
Jr Saier
A
A
Burkovski
D026921:Amino Acid Transport Systems, Neutral; D001426:Bacterial Proteins; D001692:Biological Transport; D002352:Carrier Proteins / Q000235:genetics; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins; D008565:Membrane Proteins / Q000235:genetics; D013912:Threonine / Q000096:biosynthesis*
D026921:Amino Acid Transport Systems, Neutral; D001426:Bacterial Proteins; D002352:Carrier Proteins; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; C119928:RhtB protein, E coli; C435513:ThrE protein, Corynebacterium glutamicum; D013912:Threonine