MPC1-like Is a Placental Mammal-specific Mitochondrial Pyruvate Carrier Subunit Expressed in Postmeiotic Male Germ Cells.
Selective transport of pyruvate across the inner mitochondrial membrane by the mitochondrial pyruvate carrier (MPC) is a fundamental step that couples cytosolic and mitochondrial metabolism. The recent molecular identification of the MPC complex has revealed two interacting subunits, MPC1 and MPC2. Although in yeast, an additional subunit, MPC3, can functionally replace MPC2, no alternative MPC subunits have been described in higher eukaryotes. Here, we report for the first time the existence of a novel MPC subunit termed MPC1-like (MPC1L), which is present uniquely in placental mammals. MPC1L shares high sequence, structural, and topological homology with MPC1. In addition, we provide several lines of evidence to show that MPC1L is functionally equivalent to MPC1: 1) when co-expressed with MPC2, it rescues pyruvate import in a MPC-deleted yeast strain; 2) in mammalian cells, it can associate with MPC2 to form a functional carrier as assessed by bioluminescence resonance energy transfer; 3) in MPC1 depleted mouse embryonic fibroblasts, MPC1L rescues the loss of pyruvate-driven respiration and stabilizes MPC2 expression; and 4) MPC1- and MPC1L-mediated pyruvate imports show similar efficiency. However, we show that MPC1L has a highly specific expression pattern and is localized almost exclusively in testis and more specifically in postmeiotic spermatids and sperm cells. This is in marked contrast to MPC1/MPC2, which are ubiquitously expressed throughout the organism. To date, the biological importance of this alternative MPC complex during spermatogenesis in placental mammals remains unknown. Nevertheless, these findings open up new avenues for investigating the structure-function relationship within the MPC complex.
From the Department of Cell Biology.
Benoît
B
Vanderperre
From the Department of Cell Biology.
Kristina
K
Cermakova
the Swiss Centre for Applied Human Toxicology, and the Department of Genetic Medicine and Development, University of Geneva, 1211 Geneva 4, Switzerland.
Jessica
J
Escoffier
the Swiss Centre for Applied Human Toxicology, and the Department of Genetic Medicine and Development, University of Geneva, 1211 Geneva 4, Switzerland.
Mayis
M
Kaba
From the Department of Cell Biology.
Tom
T
Bender
the Swiss Centre for Applied Human Toxicology, and the Department of Genetic Medicine and Development, University of Geneva, 1211 Geneva 4, Switzerland.
Serge
S
Nef
From the Department of Cell Biology, jean-claude.martinou@unige.ch.
Jean-Claude
JC
Martinou
D000818:Animals; D027321:Anion Transport Proteins / Q000096:biosynthesis* / Q000235:genetics; D005260:Female; D005786:Gene Expression Regulation / Q000502:physiology*; D057809:HEK293 Cells; D006801:Humans; D008297:Male; D051379:Mice; D033681:Mitochondrial Membrane Transport Proteins / Q000096:biosynthesis* / Q000235:genetics; D024101:Mitochondrial Proteins / Q000096:biosynthesis / Q000235:genetics; D027501:Monocarboxylic Acid Transporters; D013087:Spermatids / Q000166:cytology / Q000378:metabolism*; D013091:Spermatogenesis / Q000502:physiology*; D013737:Testis / Q000166:cytology / Q000378:metabolism*
D027321:Anion Transport Proteins; C573718:MPC1 protein, human; C000595573:MPC1 pyruvate carrier protein, mouse; C000595572:MPC2 protein, human; C000595574:MPC2 pyruvate carrier protein, mouse; D033681:Mitochondrial Membrane Transport Proteins; D024101:Mitochondrial Proteins; D027501:Monocarboxylic Acid Transporters
MPC1L; mitochondrial metabolism; mitochondrial pyruvate carrier; mitochondrial transport; pyruvate; spermatogenesis; testis