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Diff erent sigma subunits of bacterial RNA
polymerase (RNAP) recognize diff erent classes
of promoters. It is believed that Corynebacterium
glutamicum promoters driving transcription of
housekeeping genes are recognized by RNAP with the
primary sigma factor SigA. Th e primary-like factor SigB
is mainly involved in transcription of genes during the
transition phase between exponential and stationary
growth phases. SigC, SigD, SigE, SigH and SigM of
C. glutamicum are members of the Group 4 sigma
factors called also ECF (extracytoplasmic function)
sigma factors. We characterized promoters of various
classes by mapping the respective transcription start
points, measuring their activity under various growth
conditions by transcriptional fusions with the reporter
genes and deriving the consensus sequences of specifi c
classes. To determine, which sigma factors are involved
in recognition of particular promoters, we have
developed the fi rst in vitro transcription system for C.
glutamicum. Th e in vitro transcription system consists
of the promoter-carrying DNA template and RNAP
holoenzyme reconstituted from the purifi ed His-tagged
core RNAP and a separately isolated sigma factor. Using
the in vitro assay, RNAP+SigA recognized specifi cally
the vegetative promoters Pper from the C. glutamicum
plasmid pGA1 and Pveg from Bacillus subtilis, whereas
no transcriptional activity of RNAP+SigA on the
SigH-dependent PdnaK promoter was observed. On
the other hand, RNAP+SigH recognized specifi cally
PdnaK promoter but not the vegetative promoters. In
vitro transcription system may be particularly used
for characterization of multiple promoters of diff erent
classes and promoters recognized by two or more sigma
factors.
Biography
JiÃ?Â?i Holátko (born 1979) completed his Ph.D. from Charles University in Prague in 2009. He participates on an international project analyzing sigma factors of RNA polymerase in Corynebacterium glutamicum at postdoctoral position in the Institute of Microbiology of Czech Academy of the Sciences. He has published 6 papers in international journals and is an author of 1 European patent.
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