Molecular analysis of Physarum haemagglutinin I: lack of a signal sequence, sulphur amino acids and post-translational modifications.
The cDNAs encoding haemagglutinin I from plasmodia of Physarum polycephalum have been cloned using PCR protocols. The composite haemagglutinin I cDNA sequence, derived from several overlapping clones from PCR fragments, spans 408 nt and the 315 bp ORF encodes a polypeptide of 104 aa without a typical signal sequence. The putative molecular mass deduced from the amino acid sequence (10,760.76 Da) corresponds exactly to that determined by electrospray ionization MS (10,759.86 +/- 0.15 Da), suggesting that haemagglutinin I is not subject to post-translational modification. Haemagglutinin I lacks sulphur amino acids and has a beta-sheet as the major secondary structure. Expression of the coding sequence in Escherichia coli yielded a product that exhibits the same sugar-binding specificity as natural haemagglutinin I. The deduced amino acid sequence shows little similarity to that of any known lectins and thus apparently represents a novel type of lectin.
Morita
Masashi
M
Faculty of Pharmaceutical Sciences, Toyama Medical and Pharmaceutical University, Sugitani, Toyama, 930-01, Japan.
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D002851:Chromatography, High Pressure Liquid; D018076:DNA, Complementary / Q000096:biosynthesis; D004271:DNA, Fungal / Q000096:biosynthesis; D004591:Electrophoresis, Polyacrylamide Gel; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics*; D006388:Hemagglutinins / Q000737:chemistry / Q000235:genetics*; D037102:Lectins; D008969:Molecular Sequence Data; D010804:Physarum / Q000737:chemistry* / Q000235:genetics
D018076:DNA, Complementary; D004271:DNA, Fungal; D005656:Fungal Proteins; D006388:Hemagglutinins; D037102:Lectins; C112408:hemagglutinin I