Biosynthetic deuteration of Thermus thermophilus ribosomes for SANS

The extreme thermophilic bacterium, Thermus thermophilus , was cultivated in a fully deuterated medium. Two‐step adaptation of the strain HB8 Thermus thermophilus to the fully deuterated medium was used. The synthetic medium described by Findling et al. [Findling K.L., Yoshida T., Fee J.A. (1984). J. Biol. Chem. 259 , 123–125] was used with ND 4 Cl as the nitrogen source and deuterated glycerol and succinate as carbon sources. Batch cultivation (maximal optical density of the culture was 1.7 optical units at 590 nm, biomas yield was about 2 g wet cell/L) pr eceded fed‐batch cultivation (optical density was about 9 optical units at 590 nm, biomass yield was above 15 g wet cell/L) followed by continuous cultivation. It allowed to obtain deuterated biological material in large quantities. The approach for selective deuteration of RNA component of E.coli ribosomes without reconstitution stage was extended to Thermus thermophilus cultivation. However, the approarch did not produce the results obtained for E.coli . Fully deuterated ribosomes and hybrid ribosomes, where one subunit was protonated and the other one was deuterated, were obtained and their neutron scattering data were collected. The data are useful for interpreting the SANS experiments in the terms of a four‐component model of the ribosome at low resolution, which may be a preliminary model to interpret X‐ray diffraction data.