A novel Mitosomal ?-barrel Outer Membrane Protein in Entamoeba.

ABSTRACT: Entamoeba possesses a highly divergent mitochondrion-related organelle known as the mitosome. Here, we report the discovery of a novel protein in Entamoeba, which we name Mitosomal ?-barrel Outer Membrane Protein of 30?kDa (MBOMP30). Initially identified through in silico analysis, we experimentally confirmed that MBOMP30 is indeed a ?-barrel protein. Circular dichroism analysis showed MBOMP30 has a predominant ?-sheet structure. Localization to Entamoeba histolytica mitosomes was observed through Percoll-gradient fractionation and immunofluorescence assay. Mitosomal membrane integration was demonstrated by carbonate fractionation, proteinase K digestion, and immunoelectron microscopy. Interestingly, the deletion of the putative ?-signal, a sequence believed to guide ?-barrel outer membrane protein (BOMP) assembly, did not affect membrane integration, but abolished the formation of a ~240?kDa complex. MBOMP30 represents only the seventh subclass of eukaryotic BOMPs discovered to date and lacks detectable homologs outside Entamoeba, suggesting that it may be unique to Entamoeba mitosomes.

SUBMITTER: Santos HJ 

PROVIDER: S-EPMC4339806 | biostudies-literature | 2015 Feb

REPOSITORIES: biostudies-literature