No abstract

The so-called aeg-46.5 region of Escherichia coli contains genes whose expression is induced under anaerobic growth conditions in the presence of nitrate or nitrite as the terminal electron acceptor. In this work, we have examined more closely several genes of this cluster, here designated ccmABCDEFGH, that are homologous to two separate Bradyrhizobium japonicum gene clusters required for the biogenesis of c-type cytochromes. A deletion mutant of E. coli which lacked all of these genes was constructed. Maturation of indigenous c-type cytochromes synthesized under anaerobic respiratory conditions, with nitrite, nitrate, or trimethylamine N-oxide as the electron acceptor, was found to be defective in the mutant. The biogenesis of foreign cytochromes, such as the soluble B. japonicum cytochrome c550 and the membrane-bound Bacillus subtilis cytochrome c550, was also investigated. None of these cytochromes was synthesized in its mature form when expressed in the mutant, as opposed to the situation in the wild type. The results suggest that the E. coli ccm gene cluster present in the aeg-46.5 region is required for a general pathway involved in cytochrome c maturation.

The present results suggest that activated RASF, by expressing ODF, play an important role in rheumatoid bone destruction. Moreover, the data provide evidence that RASF not only activate osteoclasts, but also contribute directly to osteoclastogenesis.

Chicken erythrocyte inner histones (H2A, H2B, H3 and H4) were associated with the two complementary homopolymeric polydeoxyribonucleotides and the two alternating copolymeric polydeoxyribonucleotides. No evidence for formation of chromatin-like structures was obtained for the complexes with poly(dG) . poly(dC) or poly(dA) . poly(dT). Both poly (dGdC) . poly(dGdC) and poly(dAdT) . poly(dAdT) could be folded by histones to yield material digested by DNAase I to multiples of about 10 and by staphylococcal nuclease to 146 bp core particles. Due to the lack of sequence heterogeniety in the complex of histones with poly(dAdT) . poly(dAdT), core particles with remarkable fine structural detail are obtained. The internal organization of DNA in the AT-containing and GC-containing core particles appears not to be identical.