The E. coli strains DH5a (Stratagene) was used for selection and amplification of DNA constructs. The E. coli strains Rosetta [DE3] pLysS (Novagen) and C41 [DE3] (Avidis) were used for expression of recombinant proteins. E. coli was grown either in Luria-Bertani (LB) medium, or in minimal M9 medium supplemented with 15 NH 4 Cl.