Developing the HK97 VLP nanoplatform for selective chemical labeling and modification

The HK-97 virus-like particle (VLP) is a non-infectious protein cage structure derived from the bacteriophage HK-97 that has potential for constructing advanced bionanomaterials. In order to further develop the HK97 VLP as a nanoplatform, methods for selective modification of the different morphological forms of the VLP are desired. The HK-97 VLP undergoes a transition between a procapsid structure, being 54 nm in diameter, to a 60 nm in diameter head structure, which can be induce with a change in solution pH. The research presented here looks at the design strategy for selectively labeling the procapsid, and then to have the ability to selectively tag it with another molecule in the head structure. Based on the crystallographic structure of HK-97 the amino acid methionine at position 202 (M202) in the sequence was found to be hidden in the prohead conformation, but becomes exposed in the head morphological structure. This amino acid was therefore identified as a potential sight for selective labeling of the head structure versus the prohead structure. The results presented here are for investigating HK-97 VLP M202 mutants and examining the ability to selectively label it in its different forms.