Zim17, a Novel Zinc Finger Protein Essential for Protein Import into Mitochondria

• Published in: The Journal of biological chemistry 2004-11, Vol.279 (48), p.50243-50249
• Main Authors: Burri, Lena, Vascotto, Katherine, Fredersdorf, Steffen, Tiedt, Ralph, Hall, Michael N., Lithgow, Trevor
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Arabidopsis Proteins - metabolism; Base Sequence; DNA-Binding Proteins - metabolism; HSP70 Heat-Shock Proteins - metabolism; Membrane Transport Proteins - metabolism; Mitochondria - metabolism; Mitochondrial Membrane Transport Proteins - metabolism; Mitochondrial Proteins - genetics; Mitochondrial Proteins - metabolism; Molecular Sequence Data; Protein Structure, Tertiary; Protein Transport - physiology; RNA-Binding Proteins - metabolism; Saccharomyces cerevisiae; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - metabolism; Saccharomyces cerevisiae Proteins - genetics; Saccharomyces cerevisiae Proteins - metabolism; Zinc Fingers - genetics; Zinc Fingers - physiology
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M409194200

Translocation of precursor proteins across the mitochondrial membranes requires the coordinated action of multisubunit translocases in the outer and inner membrane, and the driving force for translocation across the inner membrane is provided by the matrix-located heat shock protein 70 (mtHsp70). The central components of the protein import machinery are essential. Here we describe Zim17, an essential protein with a zinc finger motif involved in protein import into mitochondria. Comparative genomics suggested a correction to the open reading frame of YNL310c, the gene encoding Zim17 in Saccharomyces cerevisiae. The revised open reading frame codes for a classic mitochondrial targeting signal, which is processed from Zim17 in the mitochondrial matrix. Loss of Zim17 selectively diminishes import of proteins into the matrix of mitochondria, but this loss of Zim17 is partially suppressed by overexpression of the J-protein Pam18/Tim14. We propose that Zim17 functions as an example of a “fractured” J-protein, where a protein like Zim17 contributes a zinc finger domain to Type III J-proteins, in toto providing for substrate loading onto Hsp70.