The insert region of the Rac GTPases is dispensable for activation of superoxide-producing NADPH oxidases

Kei Miyano, Hirofumi Koga, Reiko Minakami, Hideki Sumimoto

Research output: Contribution to journalArticle

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Abstract

Rac1 and Rac2, which belong to the Rho subfamily of Ras-related GTPases, play an essential role in activation of gp91phox/Nox2 (cytochrome b-245, β polypeptide; also known as Cybb), the catalytic core of the superoxide-producing NADPH oxidase in phagocytes. Rac1 also contributes to activation of the non-phagocytic oxidases Nox1 (NADPH oxidase 1) and Nox3 (NADPH oxidase 3), each related closely to gp91phox/Nox2. It has remained controversial whether the insert region of Rac (amino acids 123-135), unique to the Rho subfamily proteins, is involved in gp91phox/Nox2 activation. In the present study we show that removal of the insert region from Rac1 neither affects activation of gp91phox/Nox2, which is reconstituted under cell-free and whole-cell conditions, nor blocks its localization to phagosomes during ingestion of IgG-coated beads by macrophage-like RAW264.7 cells. The insert region of Rac2 is also dispensable for gp91phox/Nox2 activation at the cellular level. Although Rac2, as well as Rac1, is capable of enhancing superoxide production by Nox1 and Nox3, the enhancements by the two GTPases are both independent of the insert region. We also demonstrate that Rac3, a third member of the Rac family in mammals, has an ability to activate the three oxidases and that the activation does not require the insert region. Thus the insert region of the Rac GTPases does not participate in regulation of the Nox family NADPH oxidases.

Original languageEnglish
Pages (from-to)373-382
Number of pages10
JournalBiochemical Journal
Volume422
Issue number2
DOIs
Publication statusPublished - Sep 1 2009

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NADPH Oxidase
GTP Phosphohydrolases
Superoxides
Chemical activation
Oxidoreductases
Phagosomes
Aptitude
Monomeric GTP-Binding Proteins
Phagocytes
Mammals
Catalytic Domain
Eating
Immunoglobulin G
Macrophages
Amino Acids
Peptides
Proteins
NADPH oxidase 1

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Cite this

The insert region of the Rac GTPases is dispensable for activation of superoxide-producing NADPH oxidases. / Miyano, Kei; Koga, Hirofumi; Minakami, Reiko; Sumimoto, Hideki.

In: Biochemical Journal, Vol. 422, No. 2, 01.09.2009, p. 373-382.

Research output: Contribution to journalArticle

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