title: Screening, Cloning and Expression of Active Streptokinase from an Iranian Isolate of S.equisimilis Group C in E. coli.
abstract: BACKGROUND
  Streptokinase (SK) is a fibrinolytic protein secreted by β-hemolytic streptococci (βHS) groups A, C and G. Due to its importance as a thrombolytic drug, national screening programs in different countries for isolation of βHS and especially SK-producing group C (GCS) strains have been conducted. Herein, we provide data of the first screening study on βHS isolates in Iran for the aim of recombinant SK (rSK) production from a local strain.
  
  
  METHODS
  252 streptococcal samples were collected and characterized using microbial/biochemical assays. The GCS strains were serologically confirmed. Activity of GCS supernatant cultures was determined by caseinolytic assay in comparison with the standard strain GCS9542. The SK gene of the highest producer strain was selected for production of rSK in E.coli system. The rSKs activities were determined using chromogenic assay.
  
  
  RESULTS
  βHS were detected in 75 of the collected specimens (29.4%) including groups A (25.8%), C (3.6%) and G (0.4%). Analyses by SDS-PAGE and Western blotting indicated the proper expression of 47 kDa rSK proteins in E. coli for SK genes which were cloned from both the selected (GCS-87) and standard (GCS-9542) strains with the yields of 0.53 and 0.59 mg/ml (of the purified protein), respectively. The calculated activity for rSK 87 was around 90% of rSK9542 activity (0.18x105 IU/mg v/s 0.21x105 IU/mg).
  
  
  CONCLUSIONS
  RESULTS of the present study for the first time provided the possibility of producing rSK from a local and native source with comparable yields and activities similar to the standard strain.
authors.affiliation: Microbiology Department, Pasteur Institute of Iran, Tehran, Iran.
authors.forename: Malihe
authors.initials: M
authors.lastname: Keramati
authors.forename: Farzin
authors.initials: F
authors.lastname: Roohvand
authors.forename: Mohammad Mehdi
authors.initials: MM
authors.lastname: Aslani
authors.forename: Shohreh
authors.initials: S
authors.lastname: Khatami
authors.forename: Mohammadreza
authors.initials: M
authors.lastname: Aghasadeghi
authors.forename: Mehdi
authors.initials: M
authors.lastname: Sadat
authors.forename: Arash
authors.initials: A
authors.lastname: Memarnejadian
authors.forename: Fatemeh
authors.initials: F
authors.lastname: Motevalli
keywords: Gene expression; Recombinant streptokinase; Streptococcus