Mic 428 Lecture

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Mic 428 - Lecture 16 Other global control
networks Alternative Sigma Factors and Heat
Shock Response
Outline
Alternative Sigma factors. s32 and its
involvement in heat shock response. Other sigma
factors in E. coli. Heat Shock Response. DnaK
role in E. coli. Quorum sensing and biofilm
formation.
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Alternative Sigma Factors
Do you remember what sigma factors are?
You may consider reviewing chapter 7, section
7.8, overview of transcription.
Some genes belonging to global control systems
involve alternative sigma factors. In this case,
regulation happens by changing either the amount
of the activity of these factors.
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Subunit of the RNS polymerase responsible for
promoter recognition.
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s70
Genes that are induced by an increase in
temperature (heat shock)
s32
Seven different sigma factors in E. coli (see
table 8.2 in your textbook)
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Heat Shock Response
s32 is rapidly degraded but when cells
experience a heat shock, this degradation process
is inhibited.
More sigma factor. More RNA polymerase directed
to more heat shock promoters.
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Heat shock proteins
DnaK
Chaperonin Molecular chaperones
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DnaK
Helps other proteins fold properly Involved in
the degradation (and also inhibiting the
activity) of s32