Ayae Honda

Two separate sequences of PB2 subunit constitute the RNA cap‐binding site of influenza virus RNA polymerase

Influenza virus RNA polymerase with the subunit composition of PB1‐PB2‐PA is a unique multifunctional enzyme with the activities of both synthesis and cleavage of RNA, and is involved in both transcription and replication of the RNA genome. Transcription is initiated by using capped RNA fragments, which are generated after cleavage of host cell mRNA by the RNA polymerase‐associated capped RNA endonuclease. To identify the RNA cap 1‐binding site on the RNA polymerase, viral ribonucleoprotein (RNP) cores were subjected to UV‐crosslinking with RNA which was labelled with 32P only at the cap‐1 structure.

Multivalent regulation of the nusA operon of Escherichia coli.

SummaryThe rate of synthesis and intracellular content of the NusA protein, a transcription termination factor, were determined for wild-type and nusA and/or nusB mutants of Escherichia coli. Both the rate and content of NusA in wild-type strains were similar to that of the RNA polymerase σ subunit, a transcription initiation factor, on a molar basis, and about 30%–40% the levels of RNA polymerase ββ′ subunits. At the stationary phase of cell growth, the values increased in parallel for both transcription factors up to approximately the level of the ββ′ subunits. In nus mutants, the rate of synthesis and the content of the σ subunit were significantly increased. These observations together suggest that the two transcription factors are coordinately regulated.