Sphingomyelin synthase 1 supports two steps of rubella virus life cycle

Summary: Our knowledge of the regulatory mechanisms that govern the replication of the rubella virus (RV) in human cells is limited. To gain insight into the host-pathogen interaction, we conducted a loss-of-function screening using the CRISPR-Cas9 system in the human placenta-derived JAR cells. We identified sphingomyelin synthase 1 (SGMS1 or SMS1) as a susceptibility factor for RV infection. Genetic knockout of SGMS1 rendered JAR cells resistant to infection by RV. The re-introduction of SGMS1 restored cellular susceptibility to RV infection. The restricted step of RV infection was post-endocytosis processes associated with the endosomal acidification. In the late phase of the RV replication cycle, the maintenance of viral persistence was disrupted, partly due to the attenuated viral gene expression. Our results shed light on the unique regulation of RV replication by a host factor during the early and late phases of viral life cycle

Biochemical Properties of a New Lantibiotic Produced by Lactococcus Zactis IO-1

A new peptide antibiotic was isolated from the culture broth of Lactococcus lactis IO-1 and biochemical properties of this compound were investigated. The peptide had a strong inhibitory effect on the growth of Bacillus subtilis Cl and the antibacterial spectrum and minimum inhibitory concentration (MIC) for various type strains showed that this antibiotic resembled nisin. Automated Edman degradation indicated the N-terminal amino acid of this peptide was isoleucine, the N-terminal amino acid for nisin. ‘H NMR spectra showed the presence of DHB,. However, hydrolysis using carboxypeptidase Y released isoleucine as the C-terminal amino acid which is not the C-terminal amino acid for nisin. The molecular weight of the IO-1 peptide is smaller than nisin and the amino acid composition was slightly different. The IO-1 peptide did not contain His and Ser and the Ile, Lys and Met content was less than that in nisin; these amino acids are the members of the C-terminal amino acid sequence of the nisin peptide. Thus, the peptide produced by strain IO-1 was a new lantibiotic with a different amino acid sequence from that of nisin