Hyperosmotic Stress Allosterically Reconfigures Betaine Binding Pocket in BetP.

The transporter BetP in C. glutamicum is essential in maintaining bacterial cell viability during hyperosmotic stress and functions by co-transporting betaine and Na into bacterial cells. Hyperosmotic stress leads to increased intracellular K concentrations which in turn promotes betaine binding.

Regulatory Role of Phospholipids in Hepatitis C Virus Replication and Protein Function.

Positive-strand RNA viruses such as hepatitis C virus (HCV) hijack key factors of lipid metabolism of infected cells and extensively modify intracellular membranes to support the viral lifecycle. While lipid metabolism plays key roles in viral particle assembly and maturation, viral RNA synthesis is closely linked to the remodeling of intracellular membranes. The formation of viral replication factories requires a number of interactions between virus proteins and host factors including lipids.

Extended interaction networks with HCV protease NS3-4A substrates explain the lack of adaptive capability against protease inhibitors.

Inhibitors against the NS3-4A protease of hepatitis C virus (HCV) have proven to be useful drugs in the treatment of HCV infection. Although variants have been identified with mutations that confer resistance to these inhibitors, the mutations do not restore replicative fitness and no secondary mutations that rescue fitness have been found. To gain insight into the molecular mechanisms underlying the lack of fitness compensation, we screened known resistance mutations in infectious HCV cell culture with different genomic backgrounds.

Molecular insights into lipid-assisted Ca regulation of the TRP channel Polycystin-2.

Polycystin-2 (PC2), a calcium-activated cation TRP channel, is involved in diverse Ca signaling pathways. Malfunctioning Ca regulation in PC2 causes autosomal-dominant polycystic kidney disease. Here we report two cryo-EM structures of distinct channel states of full-length human PC2 in complex with lipids and cations.