Part:BBa_K2748000

U24 protein from human herpesvirus 6A

U24 protein from human herpesvirus 6A is a C-terminal membrane anchored protein that can downregulate T cell receptors via endosomal recycling inhibition.

Usage and Biology

U24 is a small (87aa) tail-anchored protein(Sullivan and Coscoy, 2010) that can downregulate TCR/CD3 complex from the cell surface by exclusion of CD3 from Rab11-containing recycling endosomes and thus inhibiting TCR complex recycling back to the surface(Sullivan and Coscoy, 2008). While it was demonstrated later that U24 also downregulate transferrin(Sullivan and Coscoy, 2010), its action is relatively specific, without affecting the surface level of ICAM-1, MHC class I, ULBP1, ULBP2, CD4 and CD8(Sullivan and Coscoy, 2008). Since U24 does not colocalized with CD3, it is believed that the downregulation does not rely on the interaction of U24 with CD3 but instead results from interaction of U24 and the endosomal recycling machinery(Sullivan and Coscoy, 2010). In addition, unlike proteins from other herpesviruses that downregulate TCRs or B cell receptors (BCRs), U24 does not activate lymphocyte signaling pathways(Sullivan and Coscoy, 2008). Furthermore, it was demonstrated that U24 can impair T cell activation by antigen presenting cells(Sullivan and Coscoy, 2008).

Design Considerations

The nucleotide sequence of U24 coding sequence was retrieved from NCBI nucleotide database(NCBI Reference Sequence: NM_002006.4:465-932), and synthesized by IGE Biotechnology LTD. Biobrick prefix and suffix was added by PCR using the following primers,

U24-prefix: 5’ cggaattcgcggccgcttctagATGGATCCCCCTCGGACGC 3’

U24-suffix: 5’ AActgcagcggccgctactagtaTCATCGCCTTTGACGATTCACAT 3’

and ligated onto the pSB1C3 plasmid backbone obtained from digestion of pSB1C3-lacI-RFP(Part:BBa_J04450). The sequence was comfirmed by Sanger sequencing by IGE Biotechnology LTD using VF2 as the forward primer.

Note that this part comes in the absence of the stop codon at the end of the sequence, hence this part should be cloned into vectors with pre-existing stop codon, fused with other protein with stop codon, or added a stop codon using PCR prior to use.

Sullivan, B.M., and Coscoy, L. (2008). Downregulation of the T-cell receptor complex and impairment of T-cell activation by human herpesvirus 6 u24 protein. Journal of virology 82, 602-608. Sullivan, B.M., and Coscoy, L. (2010). The U24 protein from human herpesvirus 6 and 7 affects endocytic recycling. Journal of virology 84, 1265-1275.

Sequence and Features

Assembly Compatibility:

• 10
  COMPATIBLE WITH RFC[10]
• 12
  COMPATIBLE WITH RFC[12]
• 21
  INCOMPATIBLE WITH RFC[21]

  Illegal BamHI site found at 3
  
• 23
  COMPATIBLE WITH RFC[23]
• 25
  COMPATIBLE WITH RFC[25]
• 1000
  COMPATIBLE WITH RFC[1000]