RESUMO
Objective To obtain highly expressing cell lines by inserting the glutamine synthetase (GS) screening system and replacing the promoter of the vector.Methods The mutation of the point BamHⅠwas induced to build a new vector pIRES2-EGFP.The marker gene GS was inserted by AseⅠ and NheⅠ, and the promoter hCMV was replaced by PacⅠand NheⅠ.The new vector pHGS1.0 and the vector pIRES2-enhanced screen fluorescein protein( EGFP)-B were inserted by the recombinant protein TEM8 ( 1-227 )-VEGFR1 domain2-IgG2 ( TV-IgG2 ) gene to analyze the advantages of the expression.Results The glutamine synsthetase is successfully inserted, the human cytomegalovirus replaced, and recombinant protein is increased 5-fold by human immunoglobulin quantification kit.Conclusion The GS system is a highly protein expressing system.
RESUMO
A strain of Rhizobium meliloti has been shown to be capable of growth in the presence of methionine sulphoximine concentrations at least two orders of magnitude higher than that required for the complete inhibition of glutamine synthetase activity. Neither the specific growth rate, nor the nutritional requirements of the organism were affected by methionine sulphoximine in the medium. Rhizobium meliloti appeared to assimilate ammonia via the glutamate dehydrogenase pathway during growth in the presence of methionine sulphoximine. This suggests that Rhizobium meliloti may have some regulatory mechanism controlling ammonia assimilation that is not present in other enterobacteria possessing similar enzymatic machinery.