Phosphorylation of U24 from Human Herpes Virus type 6 (HHV-6) and its potential role in mimicking myelin basic protein (MBP) in multiple sclerosis

Abstract 

Myelin basic protein (MBP) from multiple sclerosis (MS) patients contains lower levels of phosphorylation at Thr97 than normal individuals. The significance of phosphorylation at this site is not fully understood, but it is proposed to play a role in the normal functioning of MBP. Human Herpesvirus Type 6 encodes the protein U24, which has tentatively been implicated in the pathology of MS. U24 shares a 7 amino acid stretch encompassing the Thr97 phosphorylation site of MBP: PRTPPPS. We demonstrate using a combination of mass spectrometry, thin layer chromatography and autoradiography, that U24 can be phosphorylated at the equivalent threonine. Phospho-U24 may confound signalling or other pathways in which phosphorylated MBP may participate, precipitating a pathological process.

Structured summary

Abbreviations: CNS, central nervous system, MBP, myelin basic protein, MS, multiple sclerosis, HHV-6, human herpes virus type 6, SDS–PAGE, sodium dodecyl sulfate–polyacrylamide electrophoresis, MAPK, mitogen-activated protein kinase, TLC, thin layer chromatography, pSer, phosphoserine, pThr, phosphothreonine, pTyr, phosphotyrosine, MALDI-TOF MS, matrix-assisted laser desorption ionization mass spectrometry

Keywords: U24, Mimicry, Kinase, Phosphorylation, Myelin