Two tandemly arrayed genes encode the (histidine) secretory acid phosphatases of Leishmania donovani.
Leishmania donovani promastigotes constitutively secrete a glycosylated and phosphorylated acid phosphatase activity. This secretory acid phosphatase (SAcP) was purified from L. donovani culture supernatants and amino-acid sequence was obtained from both the N-terminus and a tryptic peptide fragment derived from the isolated protein. A polymerase chain reaction (PCR)-based strategy, using degenerate oligo primers designed from the amino-acid sequence data, identified two single-copy, tandemly arrayed open reading frames (ORFs) capable of encoding the L. donovani SAcP (SAcP-1, 2052 bp and SAcP-2, 2124 bp). Both SAcP-1 and -2 were shown to be actively transcribed by L. donovani promastigotes by reverse transcription (RT) and PCR amplification. The deduced amino-acid sequences of SAcP-1 and SAcP-2 show high conservation to each other in four regions: a 23-amino-acid signal peptide; a catalytic domain containing several potential N-linked glycosylation sites; a Ser/Thr-rich repeat region containing multiple potential phosphorylation sites and a common C-terminus. Within the catalytic domain, the L. donovani SAcPs possess two conserved consensus sequences characteristic of histidine acid phosphatases (AcPs). Furthermore, antisera to native L. donovani SAcP immunoprecipitated in vitro transcription/translation products of both SAcP-1 and SAcP-2. Cumulatively, these data indicate that the acid phosphatase activity constitutively secreted by L. donovani promastigotes is composed of two (histidine) AcP isoforms that are encoded by SAcP-1 and SAcP-2, respectively.
Shakarian
A M
AM
Cell Biology Section, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892-0425, USA.
Ellis
S L
SL
Mallinson
D J
DJ
Olafson
R W
RW
Dwyer
D M
DM
D000135:Acid Phosphatase / Q000235:genetics* / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015139:Blotting, Southern; D018628:Gene Dosage; D017125:Genes, Protozoan; D006639:Histidine; D007893:Leishmania donovani / Q000235:genetics*; D008969:Molecular Sequence Data; D011233:Precipitin Tests; D014176:Protein Biosynthesis; D012333:RNA, Messenger; D017421:Sequence Analysis / Q000379:methods; D017386:Sequence Homology, Amino Acid; D014158:Transcription, Genetic
D012333:RNA, Messenger; D006639:Histidine; D000135:Acid Phosphatase