TY - JOUR
T1 - Effects of divalent metals on nanoscopic fiber formation and small molecule recognition of helical proteins
AU - Gunasekar, Susheel K.
AU - Anjia, Luona
AU - Matsui, Hiroshi
AU - Montclare, Jin K.
PY - 2012/5/23
Y1 - 2012/5/23
N2 - Metal dependent protein-based assemblies derived from the cartilage oligomeric matrix protein (C) coiled-coil domain (His 6-C) and two variants with mutation at position 40 (His 6-T40A) and 44 (His 6-L44A) are explored. All proteins have an N-terminal hexahistidine tag (His 6) that interacts with divalent metal ions Zn(II) and Ni(II). Binding to Zn(II) confers enhanced helical structure and stability, while Ni(II) promotes aggregation. Surprisingly, His 6-L44A undergoes a conformational switch from unstructured to α-helix in the presence of Zn(II). Both His 6-C and His 6-T40A further assemble into discrete nanofibers that appear to be stabilized by Zn(II) in which the fiber formation is dictated by the α-helical content. Because Ni(II) promotes aggregation, the proteins visibly cluster, forming large fiber mats in the case of His 6-C and His 6-T40A or aggregated structures as observed for His 6-L44A. Due to the unique pentameric assembly of the proteins, recognition of a small molecule within the pore is assessed using curcumin as the guest molecule. In the presence of Zn(II), there is enhanced binding to curcumin, while the addition of Ni(II) causes a loss in binding. It is shown that metal binding serves as a trigger to control the conformation of the proteins, affecting the nanoscopic fibrous assemblies and small molecule recognition abilities.
AB - Metal dependent protein-based assemblies derived from the cartilage oligomeric matrix protein (C) coiled-coil domain (His 6-C) and two variants with mutation at position 40 (His 6-T40A) and 44 (His 6-L44A) are explored. All proteins have an N-terminal hexahistidine tag (His 6) that interacts with divalent metal ions Zn(II) and Ni(II). Binding to Zn(II) confers enhanced helical structure and stability, while Ni(II) promotes aggregation. Surprisingly, His 6-L44A undergoes a conformational switch from unstructured to α-helix in the presence of Zn(II). Both His 6-C and His 6-T40A further assemble into discrete nanofibers that appear to be stabilized by Zn(II) in which the fiber formation is dictated by the α-helical content. Because Ni(II) promotes aggregation, the proteins visibly cluster, forming large fiber mats in the case of His 6-C and His 6-T40A or aggregated structures as observed for His 6-L44A. Due to the unique pentameric assembly of the proteins, recognition of a small molecule within the pore is assessed using curcumin as the guest molecule. In the presence of Zn(II), there is enhanced binding to curcumin, while the addition of Ni(II) causes a loss in binding. It is shown that metal binding serves as a trigger to control the conformation of the proteins, affecting the nanoscopic fibrous assemblies and small molecule recognition abilities.
KW - coiled-coils
KW - fibers
KW - metals
KW - self-assembly
KW - small molecule recognition
KW - stimuli-responsive materials
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U2 - 10.1002/adfm.201101627
DO - 10.1002/adfm.201101627
M3 - Article
AN - SCOPUS:84861147532
SN - 1057-9257
VL - 22
SP - 2154
EP - 2159
JO - Advanced Materials for Optics and Electronics
JF - Advanced Materials for Optics and Electronics
IS - 10
ER -