Team:SJTU-BioX-Shanghai/Project/Subproject1

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==Rare-Codon Switch==
==Rare-Codon Switch==
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Codon degeneration indicates that more than one codon can be used to encode an amino acid. Every species has '''codon usage bias'''. For one species, some codons are rarely used(less than 1%). These codons are called rare codons.  
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In natural biological system, translation process goes like this: aminoacyl tRNA synthetase (aaRS) charges tRNA with amino acid, and the tRNA recognizes the codon on the mRNA and brings the amino acid there.
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 +
Codon degeneration indicates that more than one codon can be used to encode an amino acid. Every species has '''codon usage bias'''. For one species, some codons are rarely used(less than 1%). These codons are called rare codons.
[[image:11SJTU_Rare_01.jpg|frame|''Fig 1.''When expressing heterogenous protein, researchers usually want to get rid of the negative effects brought by codon usage bias.
[[image:11SJTU_Rare_01.jpg|frame|''Fig 1.''When expressing heterogenous protein, researchers usually want to get rid of the negative effects brought by codon usage bias.
]]
]]
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Codon usage and tRNA amount are closely related. When heterogenous protein is expressed, differences in codon usage in mRNA may impede translation because one or more tRNAs are rare in the population, especially when there are multiple consecutive rare codons at the N-terminus of a coding sequence. This has proposed a new way to control protein expression on translational level.  
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Codon usage and tRNA amount are closely related. When heterogenous protein is expressed, differences in codon usage in mRNA may impede translation because one or more tRNAs are rare in the population, especially when there are multiple consecutive rare codons at the N-terminus of a coding sequence. This has proposed a new way to control protein expression on translational level.
In ''E.coli'', '''the rarest used codon is AGG for Arg'''. By adding AGG codons to the site close to initial codon and regulating the abundance of rare tRNA, we can regulate protein biosynthesis on translational level.
In ''E.coli'', '''the rarest used codon is AGG for Arg'''. By adding AGG codons to the site close to initial codon and regulating the abundance of rare tRNA, we can regulate protein biosynthesis on translational level.
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We design a Rare-Codon Switch controlling protein biosynthesis.  
We design a Rare-Codon Switch controlling protein biosynthesis.  
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We can control the translation process by controlling how well the ribosome can get through a tandem of rare codons in the target protein's mRNA.  
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We can control the translation process by controlling how well the ribosome can get through a tandem of rare codons in the target protein's mRNA. This process is controlled by two main elements: the amount of charge rare tRNA and the rare codons (including rare codon number, copy number and location) in the mRNA.
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Thus we can control the translation process by controlling three elements: the '''rare tRNA''', the '''aaRS''' that charges the rare tRNA and the '''rare codons'''.
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This process can be achieved by controlling
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See how we control the process with these three elements:
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*'''Modulator''': control '''the amount of charged rare tRNAs''' that recognize these rare codons. The amount of charged rare tRNA is controlled by two elements:
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'''rare tRNA amount'''
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**'''rare tRNA'''
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**aminoacyl tRNA synthetases '''(aaRS)'''
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*'''Reporter''': control '''the number of rare codons''' in the target protein's mRNA.
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'''aaRS'''
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[[image:11SJTU_Rare_02.jpg|center|The Design of Rare-Codon Switch]]
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'''rare codon'''
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[[image:11SJTU_arrow_next.jpg|right|Next Page|link=Team:SJTU-BioX-Shanghai/Project/Subproject1/Design]]
[[image:11SJTU_arrow_next.jpg|right|Next Page|link=Team:SJTU-BioX-Shanghai/Project/Subproject1/Design]]

Revision as of 07:47, 26 October 2011

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    Rare-Codon Switch

    In natural biological system, translation process goes like this: aminoacyl tRNA synthetase (aaRS) charges tRNA with amino acid, and the tRNA recognizes the codon on the mRNA and brings the amino acid there.

    Codon degeneration indicates that more than one codon can be used to encode an amino acid. Every species has codon usage bias. For one species, some codons are rarely used(less than 1%). These codons are called rare codons.

    Fig 1.When expressing heterogenous protein, researchers usually want to get rid of the negative effects brought by codon usage bias.

    Codon usage and tRNA amount are closely related. When heterogenous protein is expressed, differences in codon usage in mRNA may impede translation because one or more tRNAs are rare in the population, especially when there are multiple consecutive rare codons at the N-terminus of a coding sequence. This has proposed a new way to control protein expression on translational level.

    In E.coli, the rarest used codon is AGG for Arg. By adding AGG codons to the site close to initial codon and regulating the abundance of rare tRNA, we can regulate protein biosynthesis on translational level.


    Key Words

    Rare codon: codon that is used rarely or infrequently in the genome

    Rare tRNA: the low-abundant tRNA that can decode rare codon

    aaRS: aminoacyl tRNA synthetases that charges cognate tRNA with a specific amino acid


    Introduction

    We design a Rare-Codon Switch controlling protein biosynthesis.

    We can control the translation process by controlling how well the ribosome can get through a tandem of rare codons in the target protein's mRNA. This process is controlled by two main elements: the amount of charge rare tRNA and the rare codons (including rare codon number, copy number and location) in the mRNA.

    Thus we can control the translation process by controlling three elements: the rare tRNA, the aaRS that charges the rare tRNA and the rare codons.

    See how we control the process with these three elements:

    rare tRNA amount

    aaRS

    rare codon


    Next Page
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