image: A golden head centipede attacks a Kunming mouse. view more
Credit: <i>PNAS</i>
Centipedes are known to subdue large prey by using potent, broad-acting venom. However, venom synthesis requires substantial metabolic investment, and the mechanisms of action of centipede venoms remain unclear. Lei Luo et al. report that a golden head centipede (Scolopendra subspinipes mutilans) weighing around 3 g can set upon and subdue a caged laboratory mouse weighing around 45 g within 30 seconds, a single bite of the centipede injecting an estimated 30 μl of crude venom into the mouse. Biochemical analysis of centipede venom uncovered a previously uncharacterized peptide toxin -- Ssm Spooky Toxin (SsTx) -- that strongly inhibits KCNQ family potassium ion channels, in particular KCNQ4, which controls pulmonary vascular tone and arterial tension. Structural and functional analysis revealed that two interacting pairs of amino acids are crucial to the toxin's effect on KCNQ4. In vivo tests revealed that SsTx is the major vasoconstricting principle in venom, and that the toxin reduces respiratory rate and triggers hippocampal seizures in mice, as well as inducing vessel spasms, acute hypertension, and myocardial ischemia in macaque monkeys. Most of the toxin-induced effects could be reversed by the channel-opening compound retigabine, which is approved for epilepsy treatment. The findings uncover molecular targets of centipede venom and point to an antidote with clinical promise, according to the authors.
###
Article #17-14760: "Centipedes subdue giant prey by blocking KCNQ channels," by Lei Luo et al.
MEDIA CONTACT: Ren Lai, Kunming Institute of Zoology, Chinese Academy of Sciences, Yunnan, CHINA; tel: 8687165196202; e-mail: rlai@mail.kiz.ac.cn
Journal
Proceedings of the National Academy of Sciences