Evolutionary relationships and protein domain architecture in an expanded calpain superfamily in kinetoplastid parasites.

Journal article

Employing whole-genome analysis we have characterized a large family of genes coding for calpain-related proteins in three kinetoplastid parasites. We have defined a total of 18 calpain-like sequences in Trypanosoma brucei, 27 in Leishmania major, and 24 in Trypanosoma cruzi. Sequence characterization revealed a well-conserved protease domain in most proteins, although residues critical for catalytic activity were frequently altered. Many of the proteins contain a novel N-terminal sequence motif unique to kinetoplastids. Furthermore, 24 of the sequences contain N-terminal fatty acid acylation motifs indicating association of these proteins with intracellular membranes. This extended family of proteins also includes a group of sequences that completely lack a protease domain but is specifically related to other kinetoplastid calpain-related proteins by a highly conserved N-terminal domain and by genomic organization. All sequences lack the C-terminal calmodulin-related calcium-binding domain typical of most mammalian calpains. Our analysis emphasizes the highly modular structure of calpains and calpain-like proteins, suggesting that they are involved in diverse cellular functions. The discovery of this surprisingly large family of calpain-like proteins in lower eukaryotes that combines novel and conserved sequence modules contributes to our understanding of the evolution of this abundant protein family.

Authors: Ersfeld, K; Barraclough, H; Gull, K

• Publication status: Published
• Journal: Journal of molecular evolution
• Volume: 61
• Issue: 6
• Pages: 742-757
• Publication date: 2005-12-01
• DOI: 10.1007/s00239-004-0272-8
• EISSN: 1432-1432
• ISSN: 0022-2844
• Language: English
• Keywords: Trypanosoma cruzi; Leishmania major; Molecular Sequence Data; Evolution, Molecular; Databases, Protein; Animals; Sequence Alignment; Calpain; Trypanosoma brucei brucei; Protein Structure, Tertiary; Amino Acid Motifs; Amino Acid Sequence; Phylogeny; Sequence Homology, Amino Acid