The role of calcium ions in the interactions of PrP106-126 amide with model membranes.
In this work, we investigated the interactions of PrP106-126 amide with 1-palmitoyl-2-oleoyl-3-phosphocholine (POPC) and POPC/bovine brain sphingomyelin (BSM) membranes in the presence of calcium ions by in situ time-lapse atomic force microscopy (AFM) and circular dichroism (CD). The CD results show that Ca(2+) has no obvious effects on the random coil conformation of PrP106-126 amide. The tapping mode AFM results demonstrate that electrostatic interaction decreases the measured heights of supported lipid bilayers (SLBs) in HBS-Ca(2+) solution. Electrostatic interaction analysis also can be used to determine the applied force in liquid tapping mode AFM. The interactions of PrP106-126 amide with membranes by AFM demonstrate the following: (i) Ca(2+) inhibits the interaction of PrP106-126 amide with POPC lipid and (ii) the co-interaction between Ca(2+) and BSM increases the poration ability of PrP106-126 amide. These results imply that the main role of Ca(2+) in the interactions of PrP106-126 amide with membranes is changing the surface properties of the membranes.
Zhong
Jian
J
Department of Biophysics, Biomed-X Center, Peking University, Beijing, China. jianzhongpku@gmail.com
Yang
Chunhui
C
Zheng
Wenfu
W
Huang
Lixin
L
Hong
Yuankai
Y
Wang
Lijun
L
Sha
Yinlin
Y
D000577:Amides / Q000737:chemistry*; D002118:Calcium / Q000737:chemistry*; D002942:Circular Dichroism; D008051:Lipid Bilayers; D008567:Membranes, Artificial; D018625:Microscopy, Atomic Force; D008962:Models, Theoretical; D010713:Phosphatidylcholines / Q000737:chemistry; D011328:Prions / Q000737:chemistry*; D017433:Protein Structure, Secondary; D013109:Sphingomyelins / Q000737:chemistry; D055672:Static Electricity
D000577:Amides; D008051:Lipid Bilayers; D008567:Membranes, Artificial; D010713:Phosphatidylcholines; D011328:Prions; D013109:Sphingomyelins; D002118:Calcium; C028694:1-palmitoyl-2-oleoylphosphatidylcholine