Protein-protein interactions among human lens acidic and basic beta-crystallins.
Human lens beta-crystallin contains four acidic (betaA1-->betaA4) and three basic (betaB1-->betaB3) subunits. They oligomerize in the lens, but it is uncertain which subunits are involved in the oligomerization. We used a two-hybrid system to detect protein-protein interactions systematically. Proteins were also expressed for some physicochemical studies. The results indicate that all acidic-basic pairs (betaA-betaB) except betaA4-betaBs pairs show strong hetero-molecular interactions. For acidic or basic pairs, only two pairs (betaA1-betaA1 and betaA3-betaA3) show strong self-association. betaA2 and betaA4 show very weak self-association, which arises from their low solubility. Confocal fluorescence microscopy shows enormous protein aggregates in betaA2- or betaA4-crystallin transfected cells. However, coexpression with betaB2-crystallin decreased both the number and size of aggregates. Circular dichroism indicates subtle differences in conformation among beta-crystallins that may have contributed to the differences in interactions.
Liu
Bing-Fen
BF
Center for Ophthalmic Research/Surgery, Brigham and Women's Hospital, Department of Ophthalmology, Harvard Medical School, Boston, MA 02115, USA.
Liang
Jack J-N
JJ
D002942:Circular Dichroism; D015870:Gene Expression; D006367:HeLa Cells; D006801:Humans; D008856:Microscopy, Fluorescence; D011485:Protein Binding / Q000235:genetics; D020798:Two-Hybrid System Techniques; D038206:beta-Crystallin B Chain / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D038206:beta-Crystallin B Chain