Using DNA replication as an example, we demonstrate that multisite phosphorylations can support coherent origin firing and robustness against rereplication. We suggest that multisite protein
modifications provide a molecular mechanism to robustly time cellular events in the cell cycle, the circadian clock and signal transduction.”
“Bacillus anthracis is well known in connection with biological warfare. The search for new drug targets and antibiotics is highly motivated because of upcoming multiresistant strains. Thymidylate kinase is an ideal target since this enzyme is at the junction of the de novo and salvage synthesis of dTTP, an essential precursor for DNA synthesis. Here the expression and characterization of thymidylate kinase from B. anthracis (Ba-TMPK) is presented. The enzyme phosphorylated deoxythymidine-5′-monophosphate (dTMP) efficiently JSH-23 with K(m) and V(max) values of 33 mu M and 48 mu mol mg(-1) min(-1), respectively. The efficiency of deoxyuridine-5′-monophosphate phosphorylation was; similar to 10% of that of dTMP. Several dTMP analogs were tested, and D-FMAUMP (2′-fluoroarabinosyl-5-methyldeoxyuridine-5′- Entospletinib supplier monophosphate) was selectively phosphorylated with an efficiency of 172% of that of D-dTMP, but L-FMAUMP was
a poor substrate as were 5-fluorodeoxyuridine-5′-monophosphate (5FdUMP) and 2′,3′-dideoxy-2′,3′-didehydrothymidine-5′-monophosphate (d4TMP). No activity could be detected with 3′-azidothymidine-5′-monophosphate (AZTMP). The corresponding
nucleosides known as efficient anticancer and antiviral compounds were also tested, and D-FMAU was a strong inhibitor with an IC(50) value of 10 mu M, while other nucleosides-L-FMAU, dThd, 5-FdUrd, d4T, and AZT, and 2′-arabinosylthymidine-were poor inhibitors. A structure model was built for Ba-TMPK based on the Staphylococcus aureus TMPK structure. Docking with various substrates suggested mechanisms explaining the differences in substrate selectivity of the human and the bacterial TMPKs. These results may serve as a start point for development of new antibacterial agents.”
“Xenotropic murine leukemia virus (MLV)-related virus (XMRV) has been amplified from human Plasma membrane Ca2+ ATPase prostate cancer and chronic fatigue syndrome (CFS) patient samples. Other studies failed to replicate these findings and suggested PCR contamination with a prostate cancer cell line, 22Rv1, as a likely source. MLV-like sequences have also been detected in CFS patients in longitudinal samples 15 years apart. Here, we tested whether sequence data from these samples are consistent with viral evolution. Our phylogenetic analyses strongly reject a model of within-patient evolution and demonstrate that the sequences from the first and second time points represent distinct endogenous murine retroviruses, suggesting contamination.