• 我要登录|
  • 免费注册
    |
  • 我的丁香通
    • 企业机构:
    • 成为企业机构
    • 个人用户:
    • 个人中心
  • 移动端
    移动端
丁香通 logo丁香实验_LOGO
搜实验

    大家都在搜

      大家都在搜

        0 人通过求购买到了急需的产品
        免费发布求购
        发布求购
        点赞
        收藏
        wx-share
        分享

        Use of tRNA-Supplemented Host Strains for Expression of Heterologous Genes in E. coli

        互联网

        627
        Though widely used, expression of heterologous genes in E. coli can be cumbersome and often fails to yield significant amounts of the desired protein. There are a variety of reasons why a particular heterologous gene fails to yield significant amount of protein, including susceptibility of the protein to degradation or presence of sequences that act as transcriptional pause sites. However, probably the most commonly encountered problem is a mismatch of the codon preference observed in the heterologous gene from the codon usage of the E. coli host. The general problem arises form the fact that due to the redundancy of the genetic code one amino acid can be encoded by more than one codon and different organisms do not utilize each codon at the same frequency (for codon frequencies in E. coli and other organisms, see Table 1 ). Since E. coli contains 46 different tRNA genes (some of them exist in multiple copies), most codons (but not all) have a corresponding cognate tRNA (1 ). The relative expression of each tRNA gene is typically matched to the frequency of the corresponding codon in the translated RNA species. Forced, high-level expression of heterologous genes containing codons rarely utilized in E. coli can lead to depletion of the corresponding tRNA pools and subsequently to stalling of the translation process and degradation of the translated mRNA (2 4 ).

        Table 1 Codon Usage of Rare E. coli Codons in Other Organismsa

        Codon

        AGG/AGA

        CGA

        CUA

        AUA

        CCC

        (cognate tRNA gene)

        (argU )

         

        (leuW )

        (ileX/ileY )

        (proL )

        Encoded amino acid

        Arginine

        Arginine

        Leucine

        Isoleucine

        Proline

        E. coli K12

        1.2/2.1

        3.6

        3.9

        4.4

        5.5

        Homo sapiens

        11.5/11.3

        6.3

        7.0

        7.2

        20.0

        Drosphila melanogaster

        6.4/5.1

        8.5

        8.3

        9.3

        17.9

        S. cerivisiae

        9.3/21.3

        3.0

        13.4

        17.8

        6.8

        Plasmodium falciparium

        4.0/16.7

        2.4

        5.3

        44.3

        2.6

        Pyrococcus furiosus

        20.5/29.5

        0.6

        16.2

        34.8

        8.8

        Thermus aquaticus

        14.5/1.4

        1.6

        3.6

        1.4

        39.3

        Arabidopsis thaliana

        10.9/19.0

        6.3

        10.1

        13.1

        5.2

        Triticum aestivum

        11.8/6.5

        3.2

        6.3

        6.1

        14.4

        a Codon frequencies are presented as codons encountered in 1000 codons of coding sequence. This table was compiled from the codon usage web site (www.kazusa.or.jp/codon). If every codon would be evenly presented, a codon frequency of 15 would be expected.

        ad image
        提问
        扫一扫
        丁香实验小程序二维码
        实验小助手
        丁香实验公众号二维码
        扫码领资料
        反馈
        TOP
        打开小程序