Alternative Sigma Factors in the Free State Are Equilibrium Mixtures of Open and Compact Conformations
IR@IICB: CSIR-Indian Institute of Chemical Biology, Kolkata
View Archive Info| Field | Value | |
| Title |
Alternative Sigma Factors in the Free State Are Equilibrium Mixtures of Open
and Compact Conformations
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| Creator |
Raha, Paromita
Chattopadhyay, Suranjana Mukherjee, Srijata Chattopadhyay, Ruchira Roy, Koushik Roy, Siddhartha |
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| Subject |
Structural Biology & Bioinformatics
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| Description |
Conformational switching upon core RNA polymerase binding is an integral part of functioning
of bacterial sigma factors. Here, we have studied dynamical features of two alternative sigma factors. A study
of fluorescence resonance energy transfer and hydrodynamic measurements in Escherichia coli σ32 suggest a
compact shape like those found in complex with anti-sigma factors. On the other hand, the fluorescence
anisotropy of probes attached to different regions of the protein and previous hydrogen exchange
measurements suggest significant internal flexibility, particularly in the C-terminal half and region 1. In a
homologous sigma factor, σF of Mycobacterium tuberculosis, emission spectra and fluorescence resonance
energy transfer between the single tryptophan (W112) and probes placed in different regions suggest a
compact conformation for a major part of the N-terminal half encompassing region 2 and the flexible
C-terminal half. Fluorescence anisotropy measurements suggest significant flexibility in the C-terminal half
and region 1, as well. Thus, free alternative sigma factors may be in equilibrium between two conformations: a
compact one in which the promoter interacting motifs are trapped in the wrong conformation and another less
abundant one with a more open and flexible conformation. Such flexibility may be important for promoter
recognition and interaction with many partner proteins.
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| Publisher |
American Chemical Society
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| Date |
2010
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| Type |
Article
PeerReviewed |
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| Format |
application/pdf
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| Identifier |
http://www.eprints.iicb.res.in/27/1/BIOCHEMISTRY_49(45)9809%2D9819;2010[14].pdf
Raha, Paromita and Chattopadhyay, Suranjana and Mukherjee, Srijata and Chattopadhyay, Ruchira and Roy, Koushik and Roy, Siddhartha (2010) Alternative Sigma Factors in the Free State Are Equilibrium Mixtures of Open and Compact Conformations. Biochemistry, 49. pp. 9809-9819. |
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| Relation |
http:/dx.doi.org/10.1021/bi1011173
http://www.eprints.iicb.res.in/27/ |
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