Spacers increase the accessibility of peptide ligands linked to the carboxyl terminus of adenovirus minor capsid protein IX.
The efficiency and specificity of gene transfer with human adenovirus (hAd)-derived gene transfer vectors would be improved if the native viral tropism could be modified. Here, we demonstrate that the minor capsid protein IX (pIX), which is present in 240 copies in the Ad capsid, can be exploited as an anchor for heterologous polypeptides. Protein IX-deleted hAd5 vectors were propagated in hAd5 helper cells expressing pIX variants, with heterologous carboxyl-terminal extensions of up to 113 amino acids in length. The extensions evaluated consist of alpha-helical spacers up to 75 A in length and to which peptide ligands were fused. The pIX variants were efficiently incorporated into the capsids of Ad particles. On intact particles, the MYC-tagged-pIX molecules were readily accessible to anti-MYC antibodies, as demonstrated by electron microscopic analyses of immunogold-labeled virus particles. The labeling efficiency improved with increasing spacer length, suggesting that the spacers lift and expose the ligand at the capsid surface. Furthermore, we found that the addition of an integrin-binding RGD motif to the pIX markedly stimulated the transduction of coxsackievirus group B and hAd receptor-deficient endothelioma cells, demonstrating the utility of pIX modification in gene transfer. Our data demonstrate that the minor capsid protein IX can be used as an anchor for the addition of polypeptide ligands to Ad particles.
Vellinga
Jort
J
Department of Molecular Cell Biology, Leiden University Medical Centre, 2333 AL Leiden, The Netherlands.
Rabelink
Martijn J W E
MJ
Cramer
Steve J
SJ
van den Wollenberg
Diana J M
DJ
Van der Meulen
Hans
H
Leppard
Keith N
KN
Fallaux
Frits J
FJ
Hoeben
Rob C
RC
D000256:Adenoviridae / Q000235:genetics / Q000502:physiology*; D000818:Animals; D015153:Blotting, Western; D036022:Capsid Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D045744:Cell Line, Tumor; D005818:Genetic Engineering; D006801:Humans; D008024:Ligands; D051379:Mice; D016253:Microscopy, Immunoelectron; D009154:Mutation / Q000235:genetics; D011485:Protein Binding; D021381:Protein Transport; D011991:Receptors, Virus / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D013379:Substrate Specificity
D036022:Capsid Proteins; D008024:Ligands; D011991:Receptors, Virus; D011993:Recombinant Fusion Proteins; C018315:hexon capsid protein, Adenovirus