Coronavirus nucleocapsid proteins assemble constitutively in high molecular oligomers

Cong, Yingying; Kriegenburg, Franziska; de Haan, Cornelis A. M.; Reggiori, Fulvio

To determine whether the analyzed truncations also form oligomers, we sedimented bacterial extract from E. coli expressing 6xHis-tagged N1, N2a or N2b-N3 truncations on a continuous 5-20% glycerol gradient. As shown in Supplementary Fig. S2a ,b, the 6xHis-tagged N1 and 6xHis-tagged N2b-N3 truncations are both forming oligomers. In contrast, however the 6xHis-tagged N2a sediments at lower molecular weight fractions. The presence of the 6xHis-tagged N2a fusion protein in fraction 3-4 also suggest that the N2a fragment might be able to multimerize through probably a weak interaction that could not be detected by pull-down experiments. From these findings we concluded that MHV N protein oligomerizes via multiple discontinuous regions.