Team:DTU-Denmark/Regulatory mechanisms

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{{:Team:DTU-Denmark/Templates/Standard_page_begin|What is: How do (trans) sRNAs work as regulators}}
 
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==How do (trans) sRNAs work as regulators==
 
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The key-word for sRNA mediated regulation is '''base-pairing'''. A part of the sRNA shows limited complementary to the mRNA of the gene it regulates and the sRNA can thus base-pair with the mRNA. The region of base-pairing is typically only 6-20 nucleotides, and often it is only a subset of these nucleotides which seems to be critical for regulation<span class="superscript">[[#References|[2]]]</span><span class="superscript">[[#References|[3]]]</span>. This (often imperfect) base-pairing between the sRNA and target mRNA leads to changes in mRNA translation or stability - or both, and thereby influences the target gene expression<span class="superscript">[[#References|[1]]]</span>.  sRNAs can be both activators and repressors for gene expression depending on what part of the mRNA molecule they base-pair with.
 
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[[File:DTU1_sRNA_activator_repressor.png|665px|thumb|center|Overview of the mechanisms for repressing and activating trans-encoded sRNA. The orange "circles" symbolise the ribosome. Modified from<span class="superscript">[[#References|[3]]]</span>.]]
 
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'''Repressor sRNAs''' act negatively by binding to the 5’ UTR often near the ribosome binding site. The binding inhibits translation by impeding ribosome binding and/or target the mRNA for degradation by RNases (often RNase E). Note that the degradation entails irreversible regulation<span class="superscript">[[#References|[3]]]</span>. Some sRNAs act stoichiometrically meaning that they are co-degradated with the mRNA whereas others act catalytically and are not degraded in the reaction.
 
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'''Activator sRNAs''' act positively through an anti-antisense mechanism where sRNA base-pairing with the target mRNA disrupt an inhibitory secondary structure sequestering the ribosome-binding site. As a result, the ribosome-binding site is liberated and free to bind ribosomes<span class="superscript">[[#References|[3]]]</span>.
 
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<html></div><div class="whitebox article"></html>
 
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==References==
 
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[1] Beisel, Chase L., and Gisela Storz. “Base pairing small RNAs and their roles in global regulatory networks.” FEMS Microbiology Reviews 34, no. 5 (2010): 866-882.
 
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[2] van Vliet, Arnoud Hm, and Brendan W Wren. “New levels of sophistication in the transcriptional landscape of bacteria.” Genome biology. 10, no. 8 (2009).
 
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[3] Waters, Lauren S., and Gisela Storz. “Regulatory RNAs in Bacteria.” Cell 136, no. 4 (2009): 615-628.
 
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Latest revision as of 18:13, 21 September 2011