Interaction of the deafness-dystonia protein DDP/TIMM8a with the signal transduction adaptor molecule STAM1.
The Mohr-Tranebjaerg-Jensen deafness-dystonia-optic atrophy protein DDP/TIMM8a is translated on cytoplasmic ribosomes but targeted ultimately to the mitochondrial intermembrane space, where it is involved in mitochondrial protein import. STAM1 is a cytoplasmic signal-transducing adaptor molecule implicated in cytokine signaling. We report here a direct interaction between DDP and STAM1, identified by yeast two-hybrid screening and confirmed by co-immunoprecipitation, fusion protein "pull downs," and nuclear redistribution assays. DDP coordinates Zn(2+), and Zn(2+) was found to stimulate the DDP-STAM1 interaction in vitro. Endogenous STAM1 localizes predominantly to early endosomes, and we found no evidence that STAM1 is imported into mitochondria in vitro. Thus, the DDP-STAM1 interaction likely occurs in the cytoplasm or at the mitochondrial outer membrane. The DDP-STAM1 interaction requires a coiled-coil region in STAM1 that overlaps with the immunoreceptor tyrosine-based activation motif (ITAM), a region previously shown to be important for interaction with Jak2/3 and hepatocyte growth factor-regulated tyrosine kinase substrate (Hrs). Thus, DDP binding may alter the interactions of STAM1 with several cytoplasmic proteins involved in cell signaling and endosomal trafficking.
Cellular Neurology Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Building 36, Room 5W21, 9000 Rockville Pike, Bethesda, MD 20892-4164, USA.
Craig
C
Blackstone
Roland G
RG
Roberts
Daniel P
DP
Seeburg
Morgan
M
Sheng
D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D002467:Cell Nucleus / Q000737:chemistry; D003593:Cytoplasm / Q000737:chemistry; D026901:Membrane Transport Proteins; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D010750:Phosphoproteins / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*; D011506:Proteins / Q000032:analysis / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D020798:Two-Hybrid System Techniques; D015032:Zinc / Q000494:pharmacology
D026901:Membrane Transport Proteins; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D010750:Phosphoproteins; D011506:Proteins; C118122:TIMM8A protein, human; D015032:Zinc