Korean J Parasitol.  2002 Mar;40(1):17-24. 10.3347/kjp.2002.40.1.17.

Isolation and characterization of a cDNA encoding a mammalian cathepsin L-like cysteine proteinase from Acanthamoeba healyi

• Hong YC
• Hwang MY
• Yun HC
• Yu HS
• Kong HH
• Yong TS
• Chung DI

• KMID: 1384707
• DOI: http://doi.org/10.3347/kjp.2002.40.1.17

Abstract

We have cloned a cDNA encoding a cysteine proteinase of the Acanthamoeba healyi OC-3A strain isolated from the brain of a granulomatous amoebic encephalitis patient. A DNA probe for an A. healyi cDNA library screening was amplified by PCR using degenerate oligonucleotide primers designed on the basis of conserved amino acids franking the active sites of cysteine and asparagine residues that are conserved in the eukaryotic cysteine proteinases. Cysteine proteinase gene of A. healyi (AhCP1) was composed of 330 amino acids with signal sequence, a proposed pro-domain and a predicted active site made up of the catalytic residues, Cys(25), His(159), and Asn(175). Deduced amino acid sequence analysis indicated that AhCP1 belongs to ERFNIN subfamily of C1 peptidases. By Northern blot analysis, no direct correlation was observed between AhCP1 mRNA expression and virulence of Acanthamoeba, but the gene was expressed at higher level in amoebae isolated from soil than those from clinical samples. These findings raise the possibility that Ahcp1 protein may play a role in protein metabolism and digestion of phagocytosed bacteria or host tissue debris rather than in invasion of amoebae into host tissue.

Keyword

Acanthamoeba healyi; AhCP1; C1 peptidase; ERFNIN family; Cathepsin L

MeSH Terms

Acanthamoeba/*enzymology/genetics/pathogenicity
Amebiasis/parasitology
Amino Acid Sequence
Animals
Base Sequence
Cathepsins/*genetics
DNA, Protozoan/chemistry/genetics/*isolation & purification
Encephalitis/parasitology
Gene Expression
Genes, Protozoan
Humans
Molecular Sequence Data
Polymerase Chain Reaction
Protozoan Proteins/chemistry/genetics/physiology
Sequence Alignment
Virulence