| Autor: |
Polianskyte, Zydrune, Peitsaro, Nina, Eriksson, Ove |
| Předmět: |
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| Zdroj: |
FASEB Journal; Apr2007, Vol. 21 Issue 5, pA669-A669, 1/5p |
| Abstrakt: |
Mitochondria derive from endosymbiotic alpha-proteobacteria. At some point in the endosymbiotic process the molecular machinery for peptidoglycan synthesis was eradicated from the bacterial genome. Nevertheless mammalian mitochondria harbor a conserved 55 kDa protein called LACTB which is homologus to bacterial peptidoglycan-synthesizing enzymes. We have purified LACTB from rat liver mitochondria for biochemical and structural analysis. Gel filtration and 2D blue native SDS-PAGE revealed that LACTB migrates at an apparent molecular weight of >600 kDa, showing that LACTB is part of a large protein complex. Visualization of purified LACTB by electron microscopy showed filaments that were about 15 nm thickness and 100-200 nm in length. Analysis of co-purifying proteins by mass spectrometry revealed several metabolic enzymes. Homology modeling showed that all amino acids required for catalytic activity are conserved in LACTB. However, using known substrates for LACTB's bacterial homologs as test compounds we were not able to detect any enzymatic activity in purified LACTB. These findings suggest that LACTB is a dual function protein that (i) carries out hydrolysis of some as yet unidentified substrate(s) and (ii) forms a high mw polymer which might function as a scaffold for metabolic enzymes. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
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