1H, 13C, and 15N backbone chemical-shift assignments of SARS-CoV-2 non-structural protein 1 (leader protein).

The current COVID-19 pandemic caused by the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has become a worldwide health crisis, necessitating coordinated scientific research and urgent identification of new drug targets for treatment of COVID-19 lung disease. The covid19-nmr consortium seeks to support drug development by providing publicly accessible NMR data on the viral RNA elements and proteins. The SARS-CoV-2 genome comprises a single RNA of about 30 kb in length, in which 14 open reading frames (ORFs) have been annotated, and encodes approximately 30 proteins. The first two-thirds of the SARS-CoV-2 genome is made up of two large overlapping open-reading-frames (ORF1a and ORF1b) encoding a replicase polyprotein, which is subsequently cleaved to yield 16 so-called non-structural proteins. The non-structural protein 1 (Nsp1), which is considered to be a major virulence factor, suppresses host immune functions by associating with host ribosomal complexes at the very end of its C-terminus. Furthermore, Nsp1 facilitates initiation of viral RNA translation via an interaction of its N-terminal domain with the 5' untranslated region (UTR) of the viral RNA. Here, we report the near-complete backbone chemical-shift assignments of full-length SARS-CoV-2 Nsp1 (19.8 kDa), which reveal the domain organization, secondary structure and backbone dynamics of Nsp1, and which will be of value to further NMR-based investigations of both the biochemical and physiological functions of Nsp1.

NMR resonance assignments for the GSPII-B domain of the traffic ATPase PilF from Thermus thermophilus in the apo and the c-di-GMP-bound state.

The PilF protein from the thermophilic bacterium Thermus thermophilus is a traffic ATPase powering the assembly of the DNA translocation machinery as well as of type 4 pili. Thereby PilF mediates the natural transformability of T. thermophilus. PilF contains a C-terminal ATPase domain and three N-terminal domains with partial homology to so-called general secretory pathway II (GSPII) domains. These three GSPII domains (GSPII-A, GSPII-B and GSPII-C) are essential for pilus assembly and twitching motility. They show varying degrees of sequence homology to the N-terminal domain of the ATPase MshE from Vibrio cholerae which binds the bacterial second messenger molecule c-di-GMP. NMR experiments demonstrate that the GSPII-B domain of PilF also binds c-di-GMP with high affinity and forms a 1:1 complex in slow exchange on the NMR time scale. As a prerequisite for structural studies of c-di-GMP binding to the GSPII-B domain of T. thermophilus PilF we present here the NMR resonance assignments for the apo and the c-di-GMP bound state of GSPII-B. In addition, we map the binding site for c-di-GMP on the GSPII-B domain using chemical shift perturbation data and compare the dynamics of the apo and the c-di-GMP-bound state of the GSPII-B domain based on {1H},15N-hetNOE data.