title: Complementary impact of paralogous Oxa1-like proteins of Bacillus subtilis on post-translocational stages in protein secretion.
abstract: In mitochondria, chloroplasts, and Gram-negative eubacteria, Oxa1p(-like) proteins are critical for the biogenesis of membrane proteins. Here we show that the Gram-positive eubacterium Bacillus subtilis contains two functional Oxa1p orthologues, denoted SpoIIIJ and YqjG. The presence of either SpoIIIJ or YqjG is required for cell viability. Whereas SpoIIIJ is required for sporulation, YqjG is dispensable for this developmental process. The stability of two membrane proteins was found to be mildly affected upon SpoIIIJ limitation in the absence of YqjG. Surprisingly, the topology and stability of other membrane proteins remained unaffected under these conditions. In contrast, SpoIIIJ- and YqjG-limiting conditions resulted in a strong post-translocational defect in the stability of secretory proteins. Together, these data indicate that SpoIIIJ and YqjG of B. subtilis are involved in both membrane protein biogenesis and protein secretion. However, the reduced stability of secretory proteins seems to be the most prominent phenotype of SpoIIIJ/YqjG-depleted B. subtilis cells. In conclusion, our observations show that SpoIIIJ and YqjG have different, but overlapping functions in B. subtilis. Most importantly, it seems that different members of the Oxa1p protein family have acquired at least partly distinct, species-specific, functions that are essential for life.
authors.affiliation: Department of Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, P. O. Box 14, 9750 AA Haren, The Netherlands.
authors.forename: Harold
authors.initials: H
authors.lastname: Tjalsma
authors.forename: Sierd
authors.initials: S
authors.lastname: Bron
authors.forename: Jan Maarten
authors.initials: JM
authors.lastname: van Dijl
mesh_terms: D000595:Amino Acid Sequence; D000681:Amylases / Q000378:metabolism*; D001412:Bacillus subtilis / Q000254:growth & development / Q000378:metabolism*; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D002473:Cell Wall / Q000378:metabolism; D003576:Electron Transport Complex IV; D026901:Membrane Transport Proteins / Q000378:metabolism; D024101:Mitochondrial Proteins; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D021381:Protein Transport; D013171:Spores, Bacterial / Q000502:physiology; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; C079999:LipA protein, Bacteria; D026901:Membrane Transport Proteins; D024101:Mitochondrial Proteins; D009687:Nuclear Proteins; C090858:OXA1 protein; C030069:spore-specific proteins, Bacillus; D003576:Electron Transport Complex IV; D000681:Amylases