Expression of both Chlamydia pneumoniae RNase HIIs in Escherichia coli
Both genes encoding the RNase HIIs from Chlamydia pneumoniae AR 39 (discriminated as CpRNase HIIa and CpRNase HIIb in this report) were cloned and efficiently expressed in Escherichia coli. These genes amplified from Chlamydial genomes with PCR were digested with restriction endonucleases and then c...
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Published in | Protein expression and purification Vol. 40; no. 1; pp. 101 - 106 |
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Main Authors | , , , |
Format | Journal Article |
Language | English |
Published |
United States
Elsevier Inc
01.03.2005
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Subjects | |
Online Access | Get full text |
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Summary: | Both genes encoding the RNase HIIs from
Chlamydia pneumoniae AR 39 (discriminated as CpRNase HIIa and CpRNase HIIb in this report) were cloned and efficiently expressed in
Escherichia coli. These genes amplified from
Chlamydial genomes with PCR were digested with restriction endonucleases and then cloned into plasmid pET-28a predigested with the same enzymes. DNA sequencing confirmed that the constructs were correct in translation frame and coding sequence. Recombinant RNase HIIs were over-expressed by 0.5
mM IPTG induction. CpRNase HIIa existed mainly as inclusion bodies while CpRNase HIIb mainly as soluble fractions in
E. coli. The soluble proteins were 20% of total expressed CpRNase HIIa and 65% of total expressed CpRNase HIIb, respectively. Native purification and denaturing Ni–NTA purification were performed to recover the recombinant CpRNase HIIs from induced bacteria. 3.36
mg CpRNase HIIa and 18
mg CpRNase HIIb were, respectively, obtained from 1
g wet bacteria with native Ni–NTA purification. Denaturing Ni–NTA purification recovered 14.48
mg CpRNase HIIa and 10.4
mg CpRNase HIIb from 1
g wet bacteria, respectively. Although the proteins recovered by denaturing Ni–NTA purification were inactive, re-folding by dialysis against decreased concentrations of urea could generate CpRNase HIIa and CpRNase HIIb as active as those recovered by native Ni–NTA purification. These efforts offered basis for further study on the structure–function relationships and their biological importance of
Chlamydial RNase HIIs. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 1046-5928 1096-0279 |
DOI: | 10.1016/j.pep.2004.10.013 |