Expression， purification， crystallization and crystallographic study of Lutzomyia longipalpis LJL143.

Leishmaniasis is a neglected vector-borne disease with a global prevalence of over 12 million cases and 59，000 annual deaths. Transmission of the parasite requires salivary proteins， including LJL143 from the New World sandfly Lutzomyia longipalpis. LJL143 is a known marker of sandfly exposure in zoonotic hosts. LJL143 was crystallized from soluble protein expressed using Pichia pastoris. X-ray data were collected to 2.6 Å resolution from orthorhombic crystals belonging to space group P2 2 2 ， with average unit-cell parameters a = 57.39， b = 70.24， c = 79.58 Å. The crystals are predicted to have a monomer in the asymmetric unit， with an estimated solvent content of 48.5%. LJL143 has negligible homology to any reported structures， so the phases could not be determined by molecular replacement. All attempts at S-SAD failed and future studies include experimental phase determination using heavy-atom derivatives.