Related Experiment Video
Updated: Jul 14, 2026
09:13
Optimized Protocol for the Extraction of Proteins from the Human Mitral Valve
Published on: June 14, 2017
A functionally divergent hydrogenosomal peptidase with protomitochondrial ancestry
Mark T Brown1, Heather M H Goldstone, Felix Bastida-Corcuera
1Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, 609 Charles E. Young Drive East, Los Angeles, CA 90095-1489, USA.
Molecular Microbiology
|June 5, 2007
Summary
Researchers identified a novel hydrogenosomal processing peptidase (HPP) in Trichomonas vaginalis. This enzyme, unlike mitochondrial processing peptidase (MPP), functions as a homodimer, suggesting co-evolution of presequence length and peptidase structure.
Area of Science:
- Organelle biology
- Protein processing
- Eukaryotic evolution
Background:
- Organelle matrix proteins are targeted via N-terminal presequences cleaved by peptidases.
- Mitochondrial processing peptidase (MPP) typically requires alpha and beta subunits for activity.
Purpose of the Study:
- To characterize a novel metallopeptidase from Trichomonas vaginalis hydrogenosomes.
- To investigate the function, structure, and evolutionary origin of this enzyme.
Main Methods:
- Biochemical characterization of a purified recombinant metallopeptidase (HPP).
- In vitro cleavage assays using hydrogenosomal presequences.
- Phylogenetic analysis of HPP and related peptidases.
Main Results:
- Identified and purified a 47 kDa metallopeptidase, hydrogenosomal processing peptidase (HPP), localizing to hydrogenosomes.
- HPP demonstrated in vitro cleavage of hydrogenosomal presequences as a homodimer, unlike MPP.
- Phylogenetic analyses indicated a common origin for HPP and betaMPP, with gene duplication preceding lineage divergence.
Conclusions:
- HPP represents a distinct organellar processing peptidase, functioning as a homodimer.
- Organellar presequence length and processing peptidase subunit composition likely co-evolved.
- Shorter hydrogenosomal/mitosomal presequences may accommodate homodimeric or monomeric peptidases, contrasting with longer mitochondrial presequences requiring heterodimeric MPP.
More Related Videos
Related Concept Videos
01:39Mitochondrial Protein Sorting
Mitochondria are double-membrane organelles of the eukaryotes involved in cellular metabolism, signaling, ATP synthesis, and programmed cell death. Each of these processes requires specific proteins and enzymes that must be correctly sorted to the right mitochondrial subcompartment for the proper functioning of the organelle.
Most of these mitochondrial proteins are encoded by the nucleus and imported to the mitochondria as unfolded or loosely folded precursors. Mitochondrial precursors...
Most of these mitochondrial proteins are encoded by the nucleus and imported to the mitochondria as unfolded or loosely folded precursors. Mitochondrial precursors...
01:19Translocation of Proteins into the Mitochondria
Mitochondrial precursors are translocated to the internal subcompartments via independent mechanisms involving distinct protein machineries called translocases.
Sorting of outer membrane proteins:
Mitochondrial outer membrane proteins are of two types: the transmembrane, beta-barrel porins, and the membrane-anchored, alpha-helical proteins. Beta-barrel porin precursors are translocated by the TOM complex and inserted into the outer mitochondrial membrane by the SAM complex. In contrast,...
Sorting of outer membrane proteins:
Mitochondrial outer membrane proteins are of two types: the transmembrane, beta-barrel porins, and the membrane-anchored, alpha-helical proteins. Beta-barrel porin precursors are translocated by the TOM complex and inserted into the outer mitochondrial membrane by the SAM complex. In contrast,...
01:39Mitochondrial Precursor Proteins
Mitochondrial precursors are partially unfolded or loosely folded polypeptide chains. Newly synthesized precursors are inhibited from spontaneously folding into their native conformation by the cytosolic chaperones, heat shock proteins 70 (Hsp70), and mitochondrial import stimulation factors (MSFs). Precursors bound to MSFs are guided to the TOM70-TOM37 receptors, while precursors bound to Hsp70 chaperones are targetted to TOM20-TOM22 receptor complexes.
Most of the mitochondrial precursors...
Most of the mitochondrial precursors...
01:34Protein Transport into the Inner Mitochondrial Membrane
Nuclear encoded mitochondrial precursors are imported to the inner membrane in a multistep process involving two separate translocons, TIM22 and TIM23. TIM23 is a cation-selective pore that remains closed by the N terminal segment of the protein. Negative charges on the TIM23 act as a receptor for the incoming precursor, pulling the positively charged matrix-targeting sequence for peptide insertion and translocation.
Transport of mitochondrial precursors across the TIM23 channel is driven by...
Transport of mitochondrial precursors across the TIM23 channel is driven by...
01:21Structure of Porins
Mitochondria, chloroplasts, and gram-negative bacteria have transmembrane, beta-barrel proteins called porins to mediate the free diffusion of ions and metabolites across the membrane. Mitochondrial porin precursors contain conserved amino acid sequences called beta signals at their C-terminal. Beta signals have a motif of PoXGXXHyXHy (Po-Polar, X-Any amino acid, G-Glycine, Hy-LargeHydrophobic), which are crucial for precursor recognition to initiate precursor assembly. Beta-barrel precursors...
02:59Animal Mitochondrial Genetics
Among all the organelles in an animal cell, only mitochondria have their own independent genomes. Animal mitochondrial DNA is a double-stranded, closed-circular molecule with around 20,000 base pairs. Mitochondrial DNA is unique in that one of its two strands, the heavy, or H, -strand is guanine rich, whereas the complementary strand is cytosine rich and called the light, or L, -strand. Compared to nuclear DNA, mitochondrial DNA has a very low percentage of non-coding regions and is marked by...