RESUMO
The semenogelin 1 protein is secreted in the seminal vesicles. After ejaculation it is split into small peptide fragments using internal proteases. It was shown that the fragments SEM1(45-107), SEM1(49-107), SEM1(68-107) (SEM1(86-107) form amyloid fibrils, which increase the possibility of HIV infection. The article presents a protocol for the synthesis and purification of a 15N, 13C-labeled SEM1(68-107) peptide for further structural studies by high-resolution NMR spectroscopy. The work describes cloning, expression of fusion protein GB1-SEM1(68-107) in E.coli, its purification, removal of GB1 and purification of SEM1(68-107). The purity of SEM1(68-107) samples on each purification steps was evaluated by polyacrylamide gel electrophoresis under denaturing conditions (SDS-PAGE) and tricine-SDS-PAGE. The developed protocol allows to obtain SEM1(68-107) peptide for NMR studies (using 3D experiments), instead of costly solid-phase synthesis.
RESUMO
Antibiotic-resistant Staphylococcus aureus is becoming a major burden on health care systems in many countries, necessitating the identification of new targets for antibiotic development. Elongation Factor P (EF-P) is a highly conserved elongation protein factor that plays an important role in protein synthesis and bacteria virulence. EF-P undergoes unique posttranslational modifications in a stepwise manner to function correctly, but experimental information on EF-P posttranslational modifications is currently lacking for S. aureus. Here, we expressed EF-P in S. aureus to analyze its posttranslational modifications by mass spectrometry and report experimental proof of 5-aminopentanol modification of S. aureus EF-P.
