Structure and Functional Study on HigBA from Streptococcus pneumoniae
- 약학대학 약학과
- Issue Date
- 서울대학교 대학원
- Streptococcus pneumoniae; Toxin-antitoxin system; HigBA; X-ray crystallography; EMSA; RNase activity assay
- 학위논문 (석사)-- 서울대학교 대학원 약학대학 약학과, 2017. 8. 이봉진.
- Streptococcus pneumoniae is a gram-positive strain that causes
diseases mainly through respiratory infections. Diseases caused by
pneumococcal species are meningitis, bacteremia, pneumonia, otitis
and sinusitis. Patients infected with s.pneumonia have developed
antibiotic resistant strains, so new antibiotics need to be developed.
Ultimately, developing novel antibiotic candidates through structural
analysis and functional studies of proteins is a major goal.
The target TA complex protein present in the s.pneumoniae
TIGR4 strain is a type II toxin-antitoxin system and is classified
under HigBA family. The toxin protein HigB is predicted to be a
ribosome-dependent mRNA interferases, which cleave mRNAs at the ribosomal A site. The antitoxin protein HigA regulates transcription
through binding of palindromic sequence to its operator region.
In order to obtain the tertiary structure of the protein, the target
protein was obtained by recombinant process and was over-expressed
in Rosetta (DE3) pLysS of escherichia coli. Affinity chromatography
was used to purify the hexa-histidine tagged protein. Further, higher
purity of target protein was obtained by ion-exchange
chromatography and size-exclusion chromatography. The structure of
target protein was obtained using X-ray crystallography techniques.