Solubility of rare codon content recombinant proteins in a codon bias-ajusted E. coli strain

ROSANO, G. L.; CECCARELLI, E. A.

Villa Carlos Paz, Córdoba

Congreso; XLIV Reunión Anual de la Sociedad Argentina de investigación en Bioquímica y Biología Molecular (SAIB); 2008

Sociedad Argentina de investigación en Bioquímica y Biología Molecular (SAIB)

The expression of heterologous proteins in E. coli is stronglyaffected by codon bias. This phenomenon occurs when the codonusage of the mRNA coding for the foreign protein differs from thatof E. coli resulting in frequent ribosome pausing. To overcome thiseffect, E. coli strains engineered to provide high levels of raretRNAs are available (CodonPlus, CP). However, the increasedspeed of translation could cause aggregation of slow foldingdomains. To test this possibility, we have studied the expression ofeight proteins from plants in E. coli BL21(DE3) pLysS´ and CP.First, we sorted them in two groups according to the percentage ofrare codon content (RCC) (group L, RCC<5%; group H,RCC>5%). We then assessed the solubility of these proteins afterexpression in E. coli and found that the group L proteins werehighly soluble in both strains. However, the group H proteins werelocalized in the insoluble fraction in the CP strain, while a portioncould be recovered in the soluble fraction in the pLysS´ strain.Moreover, the expression of group H proteins in the CP straincaused retarded growth and low cell yield due to massiveaccumulation of inclusion bodies. Our results show that theexpression of high RCC proteins in the CP strain is detrimental forprotein solubility. We propose that the RCC could be a usefulpredictor of protein solubility in codon bias-adjusted strains.