Characterization and expression of the cDNA encoding a new kind of phospholipid transfer protein, the phosphatidylglycerol/phosphatidylinositol transfer protein from Aspergillus oryzae: evidence of a putative membrane targeted phospholipid transfer protein in fungi

The full-length cDNA of a phospholipid transfer protein (PLTP) was isolated from Aspergillus oryzae by a RACE-PCR procedure using degenerated primer p ool selected from the N-terminal sequence of the purified phosphatidylinosi tol/ phosphatidylglycerol transfer protein (PG/PI-TP), The cDNA encodes a 1 73 amino acid protein of 18 823 Da. The deduced amino acid sequence from po sition 38 to 67 is 100% identical to the N-terminal sequence (first 30 amin o acids) of the purified PG/PI-TP. This amino acid sequence is preceded by a leader peptide of 37 amino acids which is predicted to be composed of a s ignal peptide of 21 amino acids followed by an extra-sequence of 16 amino a cids, or a membrane anchor protein signal (amino acid 5-29). This strongly suggests that the PG/PI-TP is a targeted protein. The deduced mature protei n is 138 amino acids longs with a predicted molecular mass of 14 933 Da. Co mparison of the deduced PG/PI-TP sequence with other polypeptide sequences available in databases revealed a homology with a protein deduced from an o pen reading frame coding for an unknown protein in Saccharomyces cerevisiae (36% identity and 57% similarity). Apart from this homology, the PG/PI-TP is unique and specific to the filamentous fungi on the basis of comparison of PLTP protein sequences. Northern blot analysis of RNA isolated from A. o ryzae cultures grown on glucose or glucose supplemented with phospholipids suggests that the PG/PI-TP is transcribed by only one RNA species and allow s us to show that expression of the protein is regulated at the messenger R NA level. (C) 1999 Elsevier Science B.V. All rights reserved.