Regulatory sequences and a novel gene in the msp (GP63) gene cluster of Leishmania chagasi.
The surface protease GP63 of Leishmania chagasi is encoded by a cluster of more than 18 tandem major surface protease (msp) genes belonging to three classes (mspL, mspS, mspC). mspL and mspS transcripts are differentially expressed during parasite growth. RNAs from mspS genes predominate during stationary phase, the time when parasite virulence and GP63 expression are maximal. We hypothesized that the unique regions downstream of mspS genes contain signals important for gene expression. The 2.8 kb region between tandem mspS genes was found to contain an 882 bp open reading frame designated mag. Copies of mag were found downstream of all mspS genes in the cluster. mag hybridized faintly to bands on Northern blots and a fully processed mag cDNA was identified in a promastigote cDNA library, providing evidence that mag genes are expressed at low levels. Similar to mspS RNAs, the abundance of mag RNAs was greater in stationary phase than logarithmic phase organisms, although mag RNAs were less abundant than mspS RNAs throughout growth. Northern blots and enzyme assays of promastigotes containing plasmid constructs in which the beta-galactosidase gene was followed by sequences between mspS coding regions, either with or without mag and its downstream sequences, suggest these regions have several regulatory effects accounting for the growth-associated changes in mspS expression.
McCoy
J J
JJ
Department of Internal Medicine, University of Iowa, Iowa City 52242, USA.
Beetham
J K
JK
Ochs
D E
DE
Donelson
J E
JE
Wilson
M E
ME
D020413:3' Untranslated Regions / Q000235:genetics; D020121:5' Untranslated Regions / Q000235:genetics; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D006224:Cricetinae; D018076:DNA, Complementary / Q000032:analysis; D018507:Gene Expression Regulation, Developmental; D017125:Genes, Protozoan; D017930:Genes, Reporter; D018314:Leishmania infantum / Q000235:genetics* / Q000254:growth & development; D008666:Metalloendopeptidases / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D005810:Multigene Family; D020161:Physical Chromosome Mapping; D012045:Regulatory Sequences, Nucleic Acid; D015183:Restriction Mapping; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA
D020413:3' Untranslated Regions; D020121:5' Untranslated Regions; D018076:DNA, Complementary; D008666:Metalloendopeptidases; C055146:glycoprotein gp63, Leishmania