Polyarginine peptides, a powerful tool for delivering proteins to living cells.

PAVAROTTI M; MAYORGA L

San Luis

Congreso; XLVII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2011

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Sperm must be capacitated to undergo acrosomal reaction (AR). Incapacitated sperm permeabilized with SLO, we have demonstrated thatSNAREs are required for AR and that these proteins are assembled inneurotoxin resistant complexes. What is the condition of SNAREs beforecapacitation is unknown. For this, the effect of a neurotoxin needs tobe assessed during capacitation in living cells. As previously shown,proteins containing a polyarginine peptide can cross membranes. Togenerate a permeant neurotoxin, the light chain of tetanus toxin wascrosslinked with a polyarginine peptide. The activity of this toxin wasevaluated by a functional assay . We corroborated that, in restingnon-permeabilized capacitaded sperm, SNAREs were locked in ciscomplexes insensitive to the neurotoxin. Upon stimulation, SNAREsbecame sensible to the toxin. However, when we added the permeantneurotoxin to not capacitated sperm, SNAREs were digested, indicatingthat they were not protected in stable cis complexes. This observationsuggests that capacitation is important for stabilizing the complexes.When sperm were incubated in the absence of albumin, a key element forcapacitation in vitro, SNARE remained toxin sensitive. Our results indicatethat capacitation is important for the assembly of stable SNARE complexesrequired for acrosomal exocytosis.