Mechanism of chromatin remodeling and recovery during passage of RNA polymerase II.

Transcription of eukaryotic genes by RNA polymerase II (Pol II) is typically accompanied by nucleosome survival and minimal exchange of histones H3 and H4. The mechanism of nucleosome survival and recovery of chromatin structure remains obscure. Here we show how transcription through chromatin by Pol II is uniquely coupled with nucleosome survival.

[The unbalance of membrane phospholipid composition of Escherichia coli affects the PPHO promoter activity].

Activity of phosphate PPHO or arabinose PBAD promoter of Escherichia coli has been studied depending on the content of zwitter-ionic phosphatidylethanolamine (PE) and anionic phospholipids in membranes. In the absence of PE or under significant decrease in the content of anionic phospholipids, there is a significant decline of PPHO promoter activity but not PBAD promoter. Since the PPHO promoter belongs to the Pho-regulon--a member of the family of two-component regulatory systems of signal transduction having membrane sensors, the regulation of gene expression by phospholipids is presumed to be realized through a membrane sensor.

Effect of membrane phospholipid composition and charge of the signal peptide of Escherichia coli alkaline phosphatase on efficiency of its secretion.

The secretion of the Escherichia coli alkaline phosphatase with a different charge of signal peptide due to replacement of positively charged Lys(-20) has been studied depending on the phospholipid composition of the membranes and the activity of the translocational ATPase--protein SecA. Changing the signal peptide charge, along with a change in phospholipid composition, has been shown to reduce the efficiency of secretion. In the absence of phosphatidylethanolamine the membrane contains anionic phospholipids only, and the dependence of secretion on the signal peptide charge decreases.

[Inactivation of pgsA gene affects biosynthesis and secretion of Escherichia coli alkaline phosphatase].

Inactivation of pgsA, which is responsible for biosynthesis of anionic phospholipid phosphatidylglycerol (PG), was shown to affect biosynthesis and secretion of alkaline phosphatase (PhoA) in Escherichia coli. A decrease in PG, but not in total anionic phospholipids, correlated with reduction of PhoA secretion, suggesting the role of PG in this process. A dramatic decrease in PG (from 18 to 3, but not 8, percent of the total phospholipids) inhibited not only secretion, but also synthesis of PhoA.