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Natural variant of the Helicobacter pylori CagA oncoprotein that lost the ability to interact with PAR1.

Hashi K, Murata-Kamiya N, Varon C, Mégraud F, Dominguez-Bello MG, Hatakeyama M - Cancer Sci. (2014)

Bottom Line: In the present study, we investigated the biological activity of v225d CagA, an Amerindian CagA of H. pylori isolated from a Venezuelan Piaroa Amerindian subject, because the variant CagA does not possess a canonical CM sequence.We found that v225d CagA interacts with SHP2 but not PAR1b.Furthermore, SHP2-binding activity of v225d CagA was much lower than that of CagA of H. pylori isolated from Western countries (Western CagA). v225d CagA also displayed a reduced ability to induce the hummingbird phenotype than that of Western CagA.

View Article: PubMed Central - PubMed

Affiliation: Division of Microbiology, Graduate School of Medicine, University of Tokyo, Tokyo, Japan.

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Schematic view of CagA. (a) Upper panel: Schematic view of the EPIYA-repeat region of ABD-type East Asian CagA, ABC-type Western CagA and v225d CagA. Lower panel: sequences of the EPIYA-repeat region of v225d CagA. Gene sequences and amino acid sequences are shown in lower case letters and upper case letters, respectively. v225d CagA has EPIYA-A, EPIYA-B and EPIYA-D/CΔCM segments. The 4th to 10th amino acids in the distal CM sequence are replaced by the partial EPIYA-D/CΔCM segment (pD/CΔCM, red dotted square). (b) Sequence diversity in the EPIYA-repeat region of CagA. CM sequences are shown in red squares. ABD-type East Asian CagA has a distal CM sequence. ABC-type Western CagA has a proximal CM sequence and a distal CM sequence. In contrast, v225d CagA does not have a canonical CM sequence.
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fig01: Schematic view of CagA. (a) Upper panel: Schematic view of the EPIYA-repeat region of ABD-type East Asian CagA, ABC-type Western CagA and v225d CagA. Lower panel: sequences of the EPIYA-repeat region of v225d CagA. Gene sequences and amino acid sequences are shown in lower case letters and upper case letters, respectively. v225d CagA has EPIYA-A, EPIYA-B and EPIYA-D/CΔCM segments. The 4th to 10th amino acids in the distal CM sequence are replaced by the partial EPIYA-D/CΔCM segment (pD/CΔCM, red dotted square). (b) Sequence diversity in the EPIYA-repeat region of CagA. CM sequences are shown in red squares. ABD-type East Asian CagA has a distal CM sequence. ABC-type Western CagA has a proximal CM sequence and a distal CM sequence. In contrast, v225d CagA does not have a canonical CM sequence.

Mentions: H. pylori v225d CagA has an EPIYA-A segment, an EPIYA-B segment and an unusual EPIYA segment comprising an EPIYA-D-like sequence lacking the proximal CM sequence (Fig.1a, orange) on the right side of the EPIYA motif and an EPIYA-C-like sequence (Fig.1a, yellow) on the right side of the EPIYA motif (EPIYA-D/CΔCM). Furthermore, the distal CM sequence of v225d CagA is interrupted by the insertion of the partial EPIYA-D/CΔCM (pD/CΔCM) segment (Fig.1a, red dotted square), giving rise to the generation of a left-side CM fragment (L-CM) and a right-side CM fragment (R-CM) (Fig.1a).19 Because such an interrupted CM sequence is quite unique and its function is unknown, we first investigated the PAR1b-binding activity of v225d CagA. To do so, COS-7 cells were co-transfected with a HA-tagged CagA expression vector and an Omni-tagged PAR1b expression vector. H. pylori NCTC11637 strain-derived CagA (ABCCC CagA), which has three repeats of the EPIYA-C segment and four CM sequences, was used as a positive control. Total cell lysates (TCL) prepared were immunoprecipitated with an anti-Omni antibody followed by immunoblotting with an anti-HA antibody. Whereas ABCCC CagA was efficiently co-immunoprecipitated with PAR1b, v225d CagA was not (Fig.2a). This result indicates that v225d CagA does not bind to PAR1b in cells, even when both proteins are overexpressed.


Natural variant of the Helicobacter pylori CagA oncoprotein that lost the ability to interact with PAR1.

Hashi K, Murata-Kamiya N, Varon C, Mégraud F, Dominguez-Bello MG, Hatakeyama M - Cancer Sci. (2014)

Schematic view of CagA. (a) Upper panel: Schematic view of the EPIYA-repeat region of ABD-type East Asian CagA, ABC-type Western CagA and v225d CagA. Lower panel: sequences of the EPIYA-repeat region of v225d CagA. Gene sequences and amino acid sequences are shown in lower case letters and upper case letters, respectively. v225d CagA has EPIYA-A, EPIYA-B and EPIYA-D/CΔCM segments. The 4th to 10th amino acids in the distal CM sequence are replaced by the partial EPIYA-D/CΔCM segment (pD/CΔCM, red dotted square). (b) Sequence diversity in the EPIYA-repeat region of CagA. CM sequences are shown in red squares. ABD-type East Asian CagA has a distal CM sequence. ABC-type Western CagA has a proximal CM sequence and a distal CM sequence. In contrast, v225d CagA does not have a canonical CM sequence.
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fig01: Schematic view of CagA. (a) Upper panel: Schematic view of the EPIYA-repeat region of ABD-type East Asian CagA, ABC-type Western CagA and v225d CagA. Lower panel: sequences of the EPIYA-repeat region of v225d CagA. Gene sequences and amino acid sequences are shown in lower case letters and upper case letters, respectively. v225d CagA has EPIYA-A, EPIYA-B and EPIYA-D/CΔCM segments. The 4th to 10th amino acids in the distal CM sequence are replaced by the partial EPIYA-D/CΔCM segment (pD/CΔCM, red dotted square). (b) Sequence diversity in the EPIYA-repeat region of CagA. CM sequences are shown in red squares. ABD-type East Asian CagA has a distal CM sequence. ABC-type Western CagA has a proximal CM sequence and a distal CM sequence. In contrast, v225d CagA does not have a canonical CM sequence.
Mentions: H. pylori v225d CagA has an EPIYA-A segment, an EPIYA-B segment and an unusual EPIYA segment comprising an EPIYA-D-like sequence lacking the proximal CM sequence (Fig.1a, orange) on the right side of the EPIYA motif and an EPIYA-C-like sequence (Fig.1a, yellow) on the right side of the EPIYA motif (EPIYA-D/CΔCM). Furthermore, the distal CM sequence of v225d CagA is interrupted by the insertion of the partial EPIYA-D/CΔCM (pD/CΔCM) segment (Fig.1a, red dotted square), giving rise to the generation of a left-side CM fragment (L-CM) and a right-side CM fragment (R-CM) (Fig.1a).19 Because such an interrupted CM sequence is quite unique and its function is unknown, we first investigated the PAR1b-binding activity of v225d CagA. To do so, COS-7 cells were co-transfected with a HA-tagged CagA expression vector and an Omni-tagged PAR1b expression vector. H. pylori NCTC11637 strain-derived CagA (ABCCC CagA), which has three repeats of the EPIYA-C segment and four CM sequences, was used as a positive control. Total cell lysates (TCL) prepared were immunoprecipitated with an anti-Omni antibody followed by immunoblotting with an anti-HA antibody. Whereas ABCCC CagA was efficiently co-immunoprecipitated with PAR1b, v225d CagA was not (Fig.2a). This result indicates that v225d CagA does not bind to PAR1b in cells, even when both proteins are overexpressed.

Bottom Line: In the present study, we investigated the biological activity of v225d CagA, an Amerindian CagA of H. pylori isolated from a Venezuelan Piaroa Amerindian subject, because the variant CagA does not possess a canonical CM sequence.We found that v225d CagA interacts with SHP2 but not PAR1b.Furthermore, SHP2-binding activity of v225d CagA was much lower than that of CagA of H. pylori isolated from Western countries (Western CagA). v225d CagA also displayed a reduced ability to induce the hummingbird phenotype than that of Western CagA.

View Article: PubMed Central - PubMed

Affiliation: Division of Microbiology, Graduate School of Medicine, University of Tokyo, Tokyo, Japan.

Show MeSH
Related in: MedlinePlus