Abstract
Most aphids are dependent for their survival on prokaryotic endosymbionts assigned to the genus Buchnera. Among the functions of Buchnera species is the synthesis of tryptophan, which is required by the aphid host. In Buchnera species from the aphid Diuraphis noxia, the genes for anthranilate synthase (trpEG) were found on a plasmid which consisted of seven tandem repeats of a 3.2-kb unit and one 2.6-kb unit which differed in containing a 0.6-kb deletion. One of the 3.2-kb units contained open reading frames corresponding to trpEG; the remaining units contained trpEG pseudogenes (ψ). The nucleotide sequence upstream of trpE contained a region that has characteristics of an origin of replication (ori). Relative to trpB (a chromosomal gene), there were about two copies of the trpEG-containing plasmid. Comparisons of the nucleotide sequences of the 3.2-kb units containing trpEG and ψtrpEG indicated that must changes occurred in a 700- nucleotide segment that included the region upstream of trpE and the portion of this gene coding for the N terminus. The consequence of these changes was the silencing of trpEG by inactivation of the putative promoter region and premature termination of the TrpE peptide. In contrast, the nucleotide sequence of the segment corresponding to ori was conserved in the units containing trpEG and ψtrpEG. We offer a number of speculations on the evolutionary pressure in this lineage which resulted in the silencing of most of trpEG while still retaining the regions resembling ori.
| Original language | English |
|---|---|
| Pages (from-to) | 332-339 |
| Number of pages | 8 |
| Journal | Applied and Environmental Microbiology |
| Volume | 62 |
| Issue number | 2 |
| Publication status | Published - 1996 Feb 1 |
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All Science Journal Classification (ASJC) codes
- Biotechnology
- Food Science
- Applied Microbiology and Biotechnology
- Ecology
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The endosymbiont (Buchnera sp.) of the aphid Diuraphis noxia contains plasmids consisting of trpEG and tandem repeats of trpEG pseudogenes. / Lai, Chi Yung; Baumann, Paul; Moran, Nancy.
In: Applied and Environmental Microbiology, Vol. 62, No. 2, 01.02.1996, p. 332-339.Research output: Contribution to journal › Article
TY - JOUR
T1 - The endosymbiont (Buchnera sp.) of the aphid Diuraphis noxia contains plasmids consisting of trpEG and tandem repeats of trpEG pseudogenes
AU - Lai, Chi Yung
AU - Baumann, Paul
AU - Moran, Nancy
PY - 1996/2/1
Y1 - 1996/2/1
N2 - Most aphids are dependent for their survival on prokaryotic endosymbionts assigned to the genus Buchnera. Among the functions of Buchnera species is the synthesis of tryptophan, which is required by the aphid host. In Buchnera species from the aphid Diuraphis noxia, the genes for anthranilate synthase (trpEG) were found on a plasmid which consisted of seven tandem repeats of a 3.2-kb unit and one 2.6-kb unit which differed in containing a 0.6-kb deletion. One of the 3.2-kb units contained open reading frames corresponding to trpEG; the remaining units contained trpEG pseudogenes (ψ). The nucleotide sequence upstream of trpE contained a region that has characteristics of an origin of replication (ori). Relative to trpB (a chromosomal gene), there were about two copies of the trpEG-containing plasmid. Comparisons of the nucleotide sequences of the 3.2-kb units containing trpEG and ψtrpEG indicated that must changes occurred in a 700- nucleotide segment that included the region upstream of trpE and the portion of this gene coding for the N terminus. The consequence of these changes was the silencing of trpEG by inactivation of the putative promoter region and premature termination of the TrpE peptide. In contrast, the nucleotide sequence of the segment corresponding to ori was conserved in the units containing trpEG and ψtrpEG. We offer a number of speculations on the evolutionary pressure in this lineage which resulted in the silencing of most of trpEG while still retaining the regions resembling ori.
AB - Most aphids are dependent for their survival on prokaryotic endosymbionts assigned to the genus Buchnera. Among the functions of Buchnera species is the synthesis of tryptophan, which is required by the aphid host. In Buchnera species from the aphid Diuraphis noxia, the genes for anthranilate synthase (trpEG) were found on a plasmid which consisted of seven tandem repeats of a 3.2-kb unit and one 2.6-kb unit which differed in containing a 0.6-kb deletion. One of the 3.2-kb units contained open reading frames corresponding to trpEG; the remaining units contained trpEG pseudogenes (ψ). The nucleotide sequence upstream of trpE contained a region that has characteristics of an origin of replication (ori). Relative to trpB (a chromosomal gene), there were about two copies of the trpEG-containing plasmid. Comparisons of the nucleotide sequences of the 3.2-kb units containing trpEG and ψtrpEG indicated that must changes occurred in a 700- nucleotide segment that included the region upstream of trpE and the portion of this gene coding for the N terminus. The consequence of these changes was the silencing of trpEG by inactivation of the putative promoter region and premature termination of the TrpE peptide. In contrast, the nucleotide sequence of the segment corresponding to ori was conserved in the units containing trpEG and ψtrpEG. We offer a number of speculations on the evolutionary pressure in this lineage which resulted in the silencing of most of trpEG while still retaining the regions resembling ori.
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UR - http://www.scopus.com/inward/citedby.url?scp=0030032623&partnerID=8YFLogxK
M3 - Article
C2 - 8593038
AN - SCOPUS:0030032623
VL - 62
SP - 332
EP - 339
JO - Applied and Environmental Microbiology
JF - Applied and Environmental Microbiology
SN - 0099-2240
IS - 2
ER -