The enteropathogenic Escherichia coli (EPEC) Map effector is imported into the mitochondrial matrix by the TOM/Hsp70 system and alters organelle morphology.
Enteropathogenic Escherichia coli (EPEC) is a human intestinal pathogen and a major cause of diarrhoea, particularly among infants in developing countries. EPEC target the Map and EspF multifunctional effector proteins to host mitochondria - organelles that play crucial roles in regulating cellular processes such as programmed cell death (apoptosis). While both molecules interfere with the organelles ability to maintain a membrane potential, EspF plays the predominant role and is responsible for triggering cell death. To learn more about the Map-mitochondria interaction, we studied Map localization to mitochondria with purified mitochondria (from mammalian and yeast cells) and within intact yeast. This revealed that (i) Map targeting is dependent on the predicted N-terminal mitochondrial targeting sequence, (ii) the N-terminal 44 residues are sufficient to target proteins to mitochondria and (iii) Map import involves the mitochondrial outer membrane translocase (Tom22 and Tom40), the mitochondrial membrane potential, and the matrix chaperone, mtHsp70. These results are consistent with Map import into the mitochondria matrix via the classical import mechanism. As all known, Map-associated phenotypes in mammalian cells are independent of mitochondrial targeting, this may indicate that import serves as a mechanism to remove Map from the cytoplasm thereby regulating cytoplasmic function. Intriguingly, Map, but not EspF, alters mitochondrial morphology with deletion analysis revealing important roles for residues 101-152. Changes in mitochondrial morphology have been linked to alterations in the ability of these organelles to regulate cellular processes providing a possible additional role for Map import into mitochondria.
Institut für Mikrobiologie, Universität Hohenheim, D-70593 Stuttgart-Hohenheim, Germany.
Panagiotis
P
Papatheodorou
Grazyna
G
Domańska
Marius
M
Oxle
Johannes
J
Mathieu
Olaf
O
Selchow
Brendan
B
Kenny
Joachim
J
Rassow
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis; D002352:Carrier Proteins / Q000378:metabolism; D004926:Escherichia coli / Q000502:physiology*; D029968:Escherichia coli Proteins / Q000378:metabolism*; D018840:HSP70 Heat-Shock Proteins / Q000502:physiology*; D066298:In Vitro Techniques; D047908:Intracellular Signaling Peptides and Proteins; D008564:Membrane Potentials; D026901:Membrane Transport Proteins / Q000502:physiology*; D008928:Mitochondria / Q000378:metabolism / Q000382:microbiology / Q000502:physiology*; D033681:Mitochondrial Membrane Transport Proteins; D051336:Mitochondrial Membranes / Q000378:metabolism; D008969:Molecular Sequence Data; D021381:Protein Transport; D011817:Rabbits; D051381:Rats; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000502:physiology*
D002352:Carrier Proteins; D029968:Escherichia coli Proteins; C489109:EspFU protein, E coli; D018840:HSP70 Heat-Shock Proteins; D047908:Intracellular Signaling Peptides and Proteins; D026901:Membrane Transport Proteins; D033681:Mitochondrial Membrane Transport Proteins; D029701:Saccharomyces cerevisiae Proteins; C090857:TOM22 protein, S cerevisiae; C066555:Tom40 protein, S cerevisiae