The PE_PGRS family of proteins unique to mycobacteria is demonstrated to contain multiple calcium-binding and glycine-rich sequence motifs GGXGXD/NXUX. This sequence repeat constitutes a calcium-binding parallel beta-roll or parallel beta-helix structure and is found in RTX toxins secreted by many Gram-negative bacteria. It is predicted that the highly homologous PE PGRS proteins containing multiple copies of the nona-peptide motif could fold into similar calcium-binding structures. The implication of the predicted calcium-binding property of PE PGRS proteins in the light of macrophage-pathogen interaction and pathogenesis is presented.
Amino Acid Motifs ; Amino Acid Sequence ; Antigens, Bacterial ; chemistry ; genetics ; metabolism ; Bacterial Proteins ; chemistry ; genetics ; metabolism ; Base Sequence ; Binding Sites ; genetics ; Calcium ; metabolism ; DNA, Bacterial ; genetics ; Membrane Proteins ; chemistry ; genetics ; metabolism ; Models, Molecular ; Molecular Sequence Data ; Mycobacterium tuberculosis ; genetics ; metabolism ; Protein Structure, Secondary