title: Novel structure of the N terminus in yeast Fis1 correlates with a specialized function in mitochondrial fission.
abstract: Mitochondrial fission is facilitated by a multiprotein complex assembled at the division site. The required components of the fission machinery in Saccharomyces cerevisiae include Dnm1, Fis1, and Mdv1. In the present study, we determined the protein structure of yeast Fis1 using NMR spectroscopy. Although the six alpha-helices, as well as their folding, in the yeast Fis1 structure are similar to those of the tetratricopeptide repeat (TPR) domains of the human Fis1 structure, the two structures differ in their N termini. The N-terminal tail of human Fis1 is flexible and unstructured, whereas a major segment of the longer N terminus of yeast Fis1 is fixed to the concave face formed by the six alpha-helices in the TPR domains. To investigate the role of the fixed N terminus, exogenous Fis1 was expressed in yeast lacking the endogenous protein. Expression of yeast Fis1 protein rescued mitochondrial fission in delta fis1 yeast only when the N-terminal TPR binding segment was left intact. The presence of this segment is also correlated to the recruitment of Mdv1 to mitochondria. The conformation of the N-terminal segment embedded in the TPR pocket indicates an intra-molecular regulation of Fis1 bioactivity. Although the TPR-like helix bundle of Fis1 mediates the interaction with Dnm1 and Mdv1, the N terminus of Fis1 is a prerequisite to recruit Mdv1 to facilitate mitochondrial fission.
authors.affiliation: Biochemistry Section, Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892, USA.
authors.forename: Motoshi
authors.initials: M
authors.lastname: Suzuki
authors.forename: Albert
authors.initials: A
authors.lastname: Neutzner
authors.forename: Nico
authors.initials: N
authors.lastname: Tjandra
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Youle
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism*; D020558:GTP Phosphohydrolases / Q000737:chemistry; D005838:Genotype; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008928:Mitochondria / Q000378:metabolism*; D024101:Mitochondrial Proteins / Q000737:chemistry* / Q000502:physiology; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry; D011487:Protein Conformation; D017510:Protein Folding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000378:metabolism* / Q000502:physiology; D017386:Sequence Homology, Amino Acid; D013347:Subcellular Fractions
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; C464859:FIS1 protein, S cerevisiae; C429283:MDV1 protein, S cerevisiae; D024101:Mitochondrial Proteins; D010455:Peptides; D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins; D049452:Green Fluorescent Proteins; D020558:GTP Phosphohydrolases; C094774:DNM1 protein, S cerevisiae