Molecular cloning and partial characterization of a plant VAP33 homologue with a major sperm protein domain

In a search for proteins interacting with the resistance protein Cf9 from t omato, a new cDNA was cloned and characterized. Protein sequence database s earches suggested that the 120 residue-N terminal domain of the encoded pro tein (named VAP27) is highly similar to the VAP33 protein family from anima ls, to uncharacterized plant proteins, and to a lower extent, to the major sperm protein (MSP) from nematodes, The second half of the protein is simil ar to VAMP and to the VAP33 N-terminus comprising a predicted coiled-coil r egion followed by a transmembrane segment. The sequence/structure compariso n of VAP27 with the crystal structure of AsMSP1 from Ascaris suum, using mo lecular modeling with the threading method, suggested that the N-terminus o f VAP27 does possess a MSP-like domain that might participate in the format ion of a protein-protein network, The coiled-coil region of VAP27 was model ed based on the structure of the VAP- and VAMP-containing SNARE complex. Th e coiled-coil region might also be involved in protein-protein interactions similar to VAP-VAMP interactions. (C) 2000 Academic Press.