Leishmania major: comparison of the cathepsin L- and B-like cysteine protease genes with those of other trypanosomatids.
Cysteine proteases play important roles in the pathogenesis of several parasitic infections and have been proposed as targets for the structure-based strategy of drug design. As a first step toward applying this strategy to design inhibitors as antiparasitic agents for leishmaniasis, we have isolated and sequenced the full-length clones of two cysteine protease genes from Leishmania major. One of the genes is structurally similar to the cathepsin L-like family and the other is similar to the cathepsin B-like family of cysteine proteases. The L. major cathepsin L-like sequence has a proregion that shares high sequence similarity with other cathepsin L sequences but not cathepsin B sequences and has a proline/threonine-rich C-terminal extension. The cathepsin L-like gene occurs in multiple copies, whereas there may be only one copy of the cathepsin B-like gene. Northern blot analyses show that both genes are expressed in the promastigote and amastigote stages, and pulse field gel electrophoresis revealed that the cathepsin L- and B-like genes are each found on two nonhomologous chromosomes. The L. major L-like amino acid sequence is 75% identical to the L. mexicana sequence, 74% identical to the L. pifanoi sequence, 47% identical with the Trypanosoma cruzi sequence, 47% identical with the T. congolense sequence, and 45% identical with the T. brucei sequence. L. major is one of two trypanosomatid species for which a cathepsin B-like gene has been identified and sequenced; its amino acid sequence is 82% identical to the one from L. mexicana. Tree inference based on distance and parsimony methods of kinetoplastid cathepsin L proteins yielded independent support for phylogenetic hypotheses inferred from analyses of ribosomal RNA genes. Because the cathepsin L locus has a high level of phylogenetic signal with respect to trypanosomatid taxa, this locus has great potential utility for investigating the evolutionary history of trypanosomatids and related organisms.
Sakanari
J A
JA
Department of Pathology, University of California, V. A. Medical Center, San Francisco 94121, USA. jas@cgl.ucsf.edu
Nadler
S A
SA
Chan
V J
VJ
Engel
J C
JC
Leptak
C
C
Bouvier
J
J
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D015139:Blotting, Southern; D002401:Cathepsin B / Q000737:chemistry / Q000235:genetics*; D056668:Cathepsin L; D002403:Cathepsins / Q000737:chemistry / Q000235:genetics*; D016384:Consensus Sequence; D003546:Cysteine Endopeptidases / Q000737:chemistry / Q000235:genetics*; D017931:DNA Primers / Q000737:chemistry; D016054:DNA, Protozoan / Q000032:analysis / Q000737:chemistry; D016521:Electrophoresis, Gel, Pulsed-Field; D010450:Endopeptidases; D015971:Gene Expression Regulation, Enzymologic; D017125:Genes, Protozoan; D018320:Leishmania major / Q000145:classification / Q000201:enzymology / Q000235:genetics*; D008969:Molecular Sequence Data; D005810:Multigene Family; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D016053:RNA, Protozoan / Q000032:analysis; D014351:Trypanosomatina / Q000145:classification / Q000201:enzymology / Q000235:genetics*
D017931:DNA Primers; D016054:DNA, Protozoan; D016053:RNA, Protozoan; D002403:Cathepsins; D010450:Endopeptidases; D003546:Cysteine Endopeptidases; D002401:Cathepsin B; D056668:Cathepsin L