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Primary and secondary structure of the pore-forming peptide of pathogenic Entamoeba histolytica.

ABSTRACT: A pore-forming peptide is implicated in the potent cytolytic activity of pathogenic Entamoeba histolytica. Using NH2-terminal sequence information of this peptide, the corresponding cDNA was isolated. The cDNA-deduced amino acid sequence revealed a putative signal peptide and a mature peptide of 77 amino acids including six cysteine residues. Computer-aided secondary structure analysis predicted that the peptide would be composed of four adjacent alpha-helices, and CD spectroscopy indicated an all alpha-helical conformation. The tertiary structure appears to be stabilized by three disulfide bonds; the pore-forming activity was not sensitive to heat but was lost in the presence of reducing agents. Sequence homology was found to the saposins and to surfactant-associated protein B, both mammalian polypeptides of similar size and secondary structure but of non-lytic function. In particular, the six cysteine residues were found to be conserved, suggesting a common motif for stabilizing a favourable tertiary structure. Compared with previously characterized toxic peptides also containing three disulfide bonds, the amoeba peptide may represent a distinct class of biologically active peptides.

SUBMITTER: Leippe M

PROVIDER: S-EPMC556807 | biostudies-other | 1992 Oct

REPOSITORIES: biostudies-other

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Primary and secondary structure of the pore-forming peptide of pathogenic Entamoeba histolytica.

Leippe M M Tannich E E Nickel R R van der Goot G G Pattus F F Horstmann R D RD Müller-Eberhard H J HJ

The EMBO journal 19921001 10

A pore-forming peptide is implicated in the potent cytolytic activity of pathogenic Entamoeba histolytica. Using NH2-terminal sequence information of this peptide, the corresponding cDNA was isolated. The cDNA-deduced amino acid sequence revealed a putative signal peptide and a mature peptide of 77 amino acids including six cysteine residues. Computer-aided secondary structure analysis predicted that the peptide would be composed of four adjacent alpha-helices, and CD spectroscopy indicated an a ...[more]

PMID: 1396552

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Project description:BackgroundA number of studies have shown that peptidases and in particular cysteine peptidases constitute major pathogenicity factors in Entamoeba histolytica. Recent studies have suggested that a considerable number of genes coding for proteolytic enzymes are present within the E. histolytica genome and questions remain about the mode of expression of the various molecules.ResultsBy homology search within the recently published amoeba genome, we identified a total of 86 E. histolytica genes coding for putative peptidases, including 46 recently described peptidase genes. In total these comprise (i) 50 cysteine peptidases of different families but most of which belong to the C1 papain superfamily, (ii) 22 different metallo peptidases from at least 11 different families, (iii) 10 serine peptidases belonging to 3 different families, and (iv) 4 aspartic peptidases of only one family. Using an oligonucleotide microarray, peptidase gene expression patterns of 7 different E. histolytica isolates as well as of heat stressed cells were analysed. A total of 21 out of 79 amoeba peptidase genes analysed were found to be significantly expressed under standard axenic culture conditions whereas the remaining are not expressed or at very low levels only. In heat-stressed cells the expression of 2 and 3 peptidase genes, respectively, were either decreased or increased. Only minor differences were observed between the various isolates investigated, despite the fact that these isolates were originated from asymptomatic individuals or from patients with various forms of amoebic diseases.ConclusionEntamoeba histolytica possesses a large number of genes coding for proteolytic enzymes. Under standard culture conditions or upon heat-stress only a relatively small number of these genes is significantly expressed and only very few variations become apparent between various clinical E. histolytica isolates, calling into question the importance of these enzymes in E. histolytica pathogenicity. Further studies are required to define the precise role of most of the proteolytic enzyme for amoeba cell biology but in particular for E. histolytica virulence.

Dataset Information

Primary and secondary structure of the pore-forming peptide of pathogenic Entamoeba histolytica.

Publications

Primary and secondary structure of the pore-forming peptide of pathogenic Entamoeba histolytica.

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