Interactions of chaperonin with a weakly active anthranilate synthase from the aphid endosymbiont Buchnera aphidicola.
The endosymbiotic bacterium Buchnera provides its aphid host with essential amino acids. Buchnera is typical of intracellular symbiotic and parasitic microorganisms in having a small effective population size, which is believed to accelerate genetic drift and reduce the stability of gene products. It is hypothesized that Buchnera mitigates protein instability with an increased production of the chaperonins GroESL. In this paper, we report the expression and functional analysis of trpE, a plasmid-borne fast-evolving gene encoding the tryptophan biosynthesis enzyme anthranilate synthase. We overcame the problem of low enzyme stability by using an anthranilate synthase-deficient mutant of E. coli as the expression host and the method of genetic complementation for detection of the enzyme activity. We showed that the Buchnera anthranilate synthase was only weakly active at the temperature of 26 degrees C but became inactive at the higher temperatures of 32 degrees C and 37 degrees C and that the coexpression with chaperonin genes groESL of E. coli enhanced the function of the Buchnera enzyme. These findings are consistent with the proposed role of groESL in the Buchnera-aphid symbiosis.
Huang
Chia-Ying
CY
Department of Biology, National Changhua University of Education, 1 Jin Der Road, Changhua 50007, Taiwan, Republic of China.
Lee
Chi-Ying
CY
Wu
Hsiao-Chen
HC
Kuo
Mei-Hwa
MH
Lai
Chi-Yung
CY
D000818:Animals; D000878:Anthranilate Synthase / Q000235:genetics / Q000378:metabolism*; D001042:Aphids / Q000382:microbiology*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D020635:Buchnera / Q000201:enzymology*; D018833:Chaperonins / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics; D005816:Genetic Complementation Test; D009154:Mutation; D016133:Polymerase Chain Reaction; D011485:Protein Binding; D011994:Recombinant Proteins / Q000378:metabolism; D013559:Symbiosis
D001426:Bacterial Proteins; D011994:Recombinant Proteins; D018833:Chaperonins; D000878:Anthranilate Synthase