Figure 1

Phospholipid binding residues of eukaryotic BAR domain proteins are conserved in H. pylori CagA. (a) Local sequence alignment of CagA and F-BAR domains of representative eukaryotic proteins. The sequences are shown for: H. pylori CagA strain 26695 (UniprotKB P55980); growth arrest-specific protein 7 (GAS-7) from human (UniProtKB GAS7_HUMAN), chicken (NCBI XP_415577.2), zebrafish (NCBI XP_001333507.2), African clawed frog (NP_001090555.1); proline-serine-threonine phosphatase-interacting protein 1 (PSTPIP1) from Brandt's bat (UniProtKB S7PAL8_MYOBR), human (J3KPG6_HUMAN), rhesus macaque (UniProtKB H9ZF21_MACMU), black flying fox (UniProtKB L5JZ07_PTEAL); FCH domain only protein 2 (FCHo2) from human (NCBI NP_620137.2), Jerdon's jumping ant (Uniprot E2C5A9_HARSA), zebrafish (Uniprot F1RDR3_DANRE); FCH domain only protein 1 (FCHo1) from human (Uniprot FCHO1_HUMAN); and human formin-binding protein 17 (FBP17) (UniProtKB Q96RU3.2). Residue numbering above the sequences corresponds to CagA. Conserved residues are boxed and shown in bold. Positively charged conserved residues and their conservative substitutions are highlighted in blue. Other types of semi-conserved residues and their conservative substitutions are highlighted in orange. The positions of the amino acid substitutions associated with loss of PS-binding activity in CagA are shown by black dots. The positions of the substitutions associated with loss of lipid-binding activity in F-BAR domains are shown by stars. The predicted secondary structure of human GAS is shown in green above the sequences (cylinders represented α-helices). The secondary structure of CagA and FCHo2 derived from their respective crystal structures [16, 21] are shown in red and blue, and helices are labelled as in [16, 21]. (b) Conservation of the CagA positively charged residues equivalent to the membrane-binding residues of BAR domains. CagA amino acid sequences from 44 strains were aligned (Additional file 1) and the residue variability was plotted using a logo representation where the height of the stack indicates the sequence conservation at a given position, and the size of the letter denotes a residue’s relative frequency at that position among homologues.