title: Direct interaction between Tks proteins and the N-terminal proline-rich region (PRR) of NoxA1 mediates Nox1-dependent ROS generation.
abstract: NADPH oxidase (Nox) family enzymes are one of the main sources of cellular reactive oxygen species (ROS), which have been implicated in several physiological and pathophysiological processes. To date seven members of this family have been reported, including Nox1-5 and Duox1 and 2. With the exception of Nox2, the regulation of the Nox enzymes is still poorly understood. Nox1 is highly expressed in the colon, and requires two cytosolic regulators, the organizer subunit NoxO1 and the activator subunit NoxA1, as well as the binding of Rac1 GTPase, for its activity. Recently, we identified the c-Src substrate proteins Tks4 and Tks5 as functional members of a p47(phox)-related organizer superfamily. As a functional consequence of this interaction, Nox1 localizes to invadopodia, actin-rich membrane protrusions of cancer cells which facilitate pericellular proteolysis and invasive behavior. Here, we report that Tks4 and Tks5 directly bind to NoxA1. Moreover, the integrity of the N-terminal PRR of NoxA1 is essential for this direct interaction with the Tks proteins. When the PRR in NoxA1 is disrupted, Tks proteins cannot bind NoxA1 and lose their ability to support Nox1-dependent ROS generation. Consistent with this, Tks4 and Tks5 are unable to act as organizers for Nox2 because of their inability to interact with p67(phox), which lacks the N-terminal PRR, thus conferring a unique specificity to Tks4 and 5. Taken together, these results clarify the molecular basis for the interaction between NoxA1 and the Tks proteins and may provide new insights into the pharmacological design of a more effective anti-metastatic strategy.
authors.affiliation: Department of Immunology and Microbial Science, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, CA 92037, USA. dgianni@scripps.edu
authors.forename: Davide
authors.initials: D
authors.lastname: Gianni
authors.forename: Céline
authors.initials: C
authors.lastname: DerMardirossian
authors.forename: Gary M
authors.initials: GM
authors.lastname: Bokoch
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D033942:Adaptor Proteins, Vesicular Transport / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D045744:Cell Line, Tumor; D057809:HEK293 Cells; D006801:Humans; D047468:Immunoprecipitation; D008969:Molecular Sequence Data; D000074624:NADPH Oxidase 1; D019255:NADPH Oxidases / Q000378:metabolism; D055232:Proline-Rich Protein Domains; D011485:Protein Binding; D017382:Reactive Oxygen Species / Q000378:metabolism*; D016415:Sequence Alignment; D014162:Transfection
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; C476420:NOXA1 protein, human; D017382:Reactive Oxygen Species; C478582:SH3PXD2A protein, human; C547814:SH3PXD2B protein, human; D000074624:NADPH Oxidase 1; D019255:NADPH Oxidases; C402799:NOX1 protein, human