Structure-function relationship of conotoxin lt14a, a potential analgesic with low cytotoxicity.
A novel conotoxin lt14a containing 13 amino acid residues with an amidated C-terminus derived from Conus litteratus, belongs to C-C-C-C cysteine pattern. As the smallest peptide of conotoxin framework 14, lt14a could inhibit nicotinic acetylcholine receptor and suppress pain. To elucidate structure-function relationship, we determine the solution structure by NMR and find that lt14a comprises a short duple β-strand region and β-turn motif. An analog [K7A]-lt14a of Ala substitution for Lys in position 7 is designed. Interestingly, [K7A]-lt14a exhibits higher activity than lt14a as long-lasting analgesic in the hotplate pain model in mice. Additionally, MTT assay reveals that the two peptides have low toxicity to human cells. The studies suggest that positively charged residue may not be involved in the blocking mechanism. However, due to the Ala substitution, hydrophobic residues' patch expansion strengthens the binding ability. A hypothesis is given that in conotoxin lt14a, hydrophobic residues rather than charged residues play a key role during target binding.
Department of Biochemistry, Sun Yat-sen University, Guangzhou, 510275, People's Republic of China.
Dandan
D
Sun
Zhenghua
Z
Ren
Xiayun
X
Zeng
Yuwen
Y
You
Wuguang
W
Pan
Maojun
M
Zhou
Lei
L
Wang
Anlong
A
Xu
D019943:Amino Acid Substitution; D000700:Analgesics / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D000818:Animals; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D002851:Chromatography, High Pressure Liquid; D002942:Circular Dichroism; D020916:Conotoxins / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D052078:Conus Snail / Q000737:chemistry; D005260:Female; D056945:Hep G2 Cells; D006801:Humans; D013058:Mass Spectrometry; D008614:Meperidine / Q000494:pharmacology; D051379:Mice; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular; D017288:Pain Threshold / Q000187:drug effects; D017434:Protein Structure, Tertiary; D013329:Structure-Activity Relationship
D000700:Analgesics; D020916:Conotoxins; C514610:lt14a peptide, Conus litteratus; D008614:Meperidine