Conditional silencing of the Escherichia coli pykF gene results from artificial convergent transcription protected from Rho-dependent termination.
PykF is one of two pyruvate kinases in Escherichia coli K-12. lambdaP(L) was convergently integrated into the chromosome of the MG1655 strain, downstream of pykF, face-to-face with its native promoter. In the presence of lambdacIts857, efficient pykF ts-silencing was achieved when the 5'-terminus of the P(L)-originated antisense RNA (asRNA), consisting of the rrnG-AT sequence, converted elongation complexes of RNA polymerase to a form resistant to Rho-dependent transcription termination. pykF silencing was detected by the following features: (a) impaired growth of the strain when pykA was also disrupted and when using ribose as a non-phosphotransferase system-transporting carbon source; (b) a pattern of reduced synthesis of the full-sized pykF mRNA, mediated by reverse transcription PCR, and (c) a significant decrease in PykF activity. The advantages of anti-terminated convergent transcription were clearly manifested in the strains where the rho_a-terminator was inserted specifically to interrupt asRNA synthesis. Most likely, the target gene was silenced by transcriptional interference due to collisions between converging RNA polymerases, although, strictly, the role of cis-asRNA effects could not be excluded. While details of the mechanisms have yet to be determined, anti-terminated convergent transcription is a promising new technique for silencing other target genes.
Krylov
Alexander A
AA
Ajinomoto-Genetika Research Institute, Moscow, Russian Federation.
Airich
Larisa G
LG
Kiseleva
Evgeniya M
EM
Minaeva
Natalia I
NI
Biryukova
Irina V
IV
Mashko
Sergey V
SV
D010582:Bacteriophage lambda / Q000235:genetics; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D048168:Escherichia coli K12 / Q000235:genetics*; D029968:Escherichia coli Proteins / Q000096:biosynthesis*; D020868:Gene Silencing; D008969:Molecular Sequence Data; D039002:Prophages / Q000235:genetics; D011770:Pyruvate Kinase / Q000096:biosynthesis*; D012234:Rho Factor / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D014158:Transcription, Genetic; D016662:Virus Integration
D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D012234:Rho Factor; D011770:Pyruvate Kinase