Proapoptotic Protein Bax Heterodimerizes with Bcl-2 and Homodimerizes with Bax via a Novel Domain (BH3) Distinct from BH1 and BH2статья из журнала
Аннотация: Most members of the Bcl-2 protein family of apoptosis regulating proteins contain two evolutionarily conserved domains, termed BH1 and BH2. Both BH1 and BH2 in the Bcl-2 protein are required for its function as an inhibitor of cell death and for heterodimerization with the proapoptotic protein Bax. In this report, we mapped the region in Bax required for heterodimerization with Bcl-2 and homodimerization with Bax, using yeast two-hybrid and in vitro protein-protein interaction assays. Neither the BH1 nor the BH2 domain of Bax was required for binding to the wild-type Bcl-2 and Bax proteins. Moreover, Bax (ΔBH1) and Bax (ΔBH2) mutant proteins bound efficiently to themselves and each other, further confirming the lack of requirement for BH1 and BH2 for Bax/Bax homodimerization. Bax/Bax homodimerization was not dependent on the inclusion of the NH2-terminal 58 amino acids of the Bax protein in each dimerization partner, unlike Bcl-2/Bcl-2 homodimers which involve head-to-tail interactions between the region of Bcl-2 where BH1 and BH2 resides, and an NH2-terminal domain in Bcl-2 that contains another domain BH4 which is conserved among antiapoptotic members of the Bcl-2 family. Similarly, heterodimerization with Bcl-2 occurred without the NH2-terminal domain of either Bax or Bcl-2, suggesting a tail-to-tail interaction. The essential region in Bax required for both homodimerization with Bax and heterodimerization with Bcl-2 was mapped to residues 59-101. This region in Bax contains a stretch of 15 amino acids that is highly homologous in several members of the Bcl-2 protein family, suggesting the existence of a novel functional domain which we have termed BH3. Deletion of this 15-amino acid region abolished the ability of Bax to dimerize with itself and to heterodimerize with Bcl-2. The findings suggest that the structural features of Bax and Bcl-2 that allow them to participate in homo- and heterodimerization phenomena are markedly different, despite their amino-acid sequence similarity. Most members of the Bcl-2 protein family of apoptosis regulating proteins contain two evolutionarily conserved domains, termed BH1 and BH2. Both BH1 and BH2 in the Bcl-2 protein are required for its function as an inhibitor of cell death and for heterodimerization with the proapoptotic protein Bax. In this report, we mapped the region in Bax required for heterodimerization with Bcl-2 and homodimerization with Bax, using yeast two-hybrid and in vitro protein-protein interaction assays. Neither the BH1 nor the BH2 domain of Bax was required for binding to the wild-type Bcl-2 and Bax proteins. Moreover, Bax (ΔBH1) and Bax (ΔBH2) mutant proteins bound efficiently to themselves and each other, further confirming the lack of requirement for BH1 and BH2 for Bax/Bax homodimerization. Bax/Bax homodimerization was not dependent on the inclusion of the NH2-terminal 58 amino acids of the Bax protein in each dimerization partner, unlike Bcl-2/Bcl-2 homodimers which involve head-to-tail interactions between the region of Bcl-2 where BH1 and BH2 resides, and an NH2-terminal domain in Bcl-2 that contains another domain BH4 which is conserved among antiapoptotic members of the Bcl-2 family. Similarly, heterodimerization with Bcl-2 occurred without the NH2-terminal domain of either Bax or Bcl-2, suggesting a tail-to-tail interaction. The essential region in Bax required for both homodimerization with Bax and heterodimerization with Bcl-2 was mapped to residues 59-101. This region in Bax contains a stretch of 15 amino acids that is highly homologous in several members of the Bcl-2 protein family, suggesting the existence of a novel functional domain which we have termed BH3. Deletion of this 15-amino acid region abolished the ability of Bax to dimerize with itself and to heterodimerize with Bcl-2. The findings suggest that the structural features of Bax and Bcl-2 that allow them to participate in homo- and heterodimerization phenomena are markedly different, despite their amino-acid sequence similarity.
Год издания: 1996
Авторы: Hongbin Zha, Christine Aimé‐Sempé, Takaaki Sato, John C. Reed
Издательство: Elsevier BV
Источник: Journal of Biological Chemistry
Ключевые слова: Protein Structure and Dynamics, Cell death mechanisms and regulation, Enzyme Structure and Function
Другие ссылки: Journal of Biological Chemistry (PDF)
Journal of Biological Chemistry (HTML)
PubMed (HTML)
Journal of Biological Chemistry (HTML)
PubMed (HTML)
Открытый доступ: hybrid
Том: 271
Выпуск: 13
Страницы: 7440–7444