Identification and
Funtional Characterization of Three Postsynaptic Short-chain Neurotoxins from
Hydrophiinae, Lapemis hardwickii Gray
ZHONG Xiao-Fen,PENG Li-Sheng,WU Wen-Yan,WEI Jian-Wen,YANG
Hong,YANG Yan-Zhen,XU An-Long*
( The Opening Laboratory for Marine Functional Genomics Research,
Department of Biochemistry, School of Life Science, Zhongshan University,
Guangzhou 510275, China )
Abstract Three cDNA
clones, sn12, sn36 and sn160, encoding isoforms of
postsynaptic short-chain neurotoxins, were cloned by screening a cDNA library
of the venom from Hydrophiinae, Lapemis hardwickii Gray. The sequences
of three cDNA clones encoded proteins consisting of 60 amino acid residues.
There was only one amino acid substitution among the three isoforms SN12, SN36
and SN160 at the position 46 of mature proteins, and they were Pro46,
His46 and Arg46, respectively. The three molecules were
expressed in Escherichia coli and the recombinant proteins were
characterized. Different LD50 were obtained, namely 0.0956 mg/kg,
0.3467 mg/kg and 0.2192 mg/kg, when the SN12, SN36 and SN160 were injected into
Kunming mice(i.p.). In analgesic effect assayed by the acetic acid induced
writhing method, SN12 and SN160 showed similar analgesic effect, but SN36 had
effects significantly different with the other two. Our studies suggested that
the amino acid residues on position 46 could affect the combination between the
postsynaptic short�–hain neurotoxins and the nicotinic acetylchoine receptor,
since different amino acid substitution resulted in different biological
activities.
Key words Lapemis hardwickii Gray；postsynaptic short-chain
neurotoxin；fusion expression；biological activity
*Corresponding author： Tel, 86-20-84113655； Fax, 86-20-84038377； e-mail, [email protected]