Faculty Collaboration Database

Characterization of Mmp37p, a Saccharomyces cerevisiae mitochondrial matrix protein with a role in mitochondrial protein import. Mol Biol Cell 2006 Sep;17(9):4051-62

Date

06/23/2006

Pubmed ID

16790493

Pubmed Central ID

PMC1556384

DOI

10.1091/mbc.e06-04-0366

Scopus ID

2-s2.0-33748108494 (requires institutional sign-in at Scopus site)   52 Citations

Abstract

Many mitochondrial proteins are encoded by nuclear genes and after translation in the cytoplasm are imported via translocases in the outer and inner membranes, the TOM and TIM complexes, respectively. Here, we report the characterization of the mitochondrial protein, Mmp37p (YGR046w) and demonstrate its involvement in the process of protein import into mitochondria. Haploid cells deleted of MMP37 are viable but display a temperature-sensitive growth phenotype and are inviable in the absence of mitochondrial DNA. Mmp37p is located in the mitochondrial matrix where it is peripherally associated with the inner membrane. We show that Mmp37p has a role in the translocation of proteins across the mitochondrial inner membrane via the TIM23-PAM complex and further demonstrate that substrates containing a tightly folded domain in close proximity to their mitochondrial targeting sequences display a particular dependency on Mmp37p for mitochondrial import. Prior unfolding of the preprotein, or extension of the region between the targeting signal and the tightly folded domain, relieves their dependency for Mmp37p. Furthermore, evidence is presented to show that Mmp37 may affect the assembly state of the TIM23 complex. On the basis of these findings, we hypothesize that the presence of Mmp37p enhances the early stages of the TIM23 matrix import pathway to ensure engagement of incoming preproteins with the mtHsp70p/PAM complex, a step that is necessary to drive the unfolding and complete translocation of the preprotein into the matrix.

Author List

Gallas MR, Dienhart MK, Stuart RA, Long RM

Author

Roy M. Long PhD Assistant Dean, Associate Professor in the Medical School Regional Campuses department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Cell Survival
Chaperonin 60
Chaperonins
DNA, Mitochondrial
HSP40 Heat-Shock Proteins
Haploidy
Heat-Shock Proteins
Meiosis
Membrane Proteins
Membrane Transport Proteins
Mitochondria
Mitochondrial Membrane Transport Proteins
Mitochondrial Membranes
Mitochondrial Proteins
Open Reading Frames
Protein Folding
Protein Precursors
Protein Structure, Quaternary
Protein Structure, Tertiary
Protein Transport
Saccharomyces cerevisiae
Saccharomyces cerevisiae Proteins