title: The role of the strictly conserved positively charged residue differs among the Gram-positive, Gram-negative, and chloroplast YidC homologs.
abstract: Recently, the structure of YidC2 from Bacillus halodurans revealed that the conserved positively charged residue within transmembrane segment one (at position 72) is located in a hydrophilic groove that is embedded in the inner leaflet of the lipid bilayer. The arginine residue was essential for the Bacillus subtilis SpoIIIJ (YidC1) to insert MifM and to complement a SpoIIIJ mutant strain. Here, we investigated the importance of the conserved positively charged residue for the function of the Escherichia coli YidC, Streptococcus mutans YidC2, and the chloroplast Arabidopsis thaliana Alb3. Like the Gram-positive B. subtilis SpoIIIJ, the conserved arginine was required for functioning of the Gram-positive S. mutans YidC2 and was necessary to complement the E. coli YidC depletion strain and to promote insertion of a YidC-dependent membrane protein synthesized with one but not two hydrophobic segments. In contrast, the conserved positively charged residue was not required for the E. coli YidC or the A. thaliana Alb3 to functionally complement the E. coli YidC depletion strain or to promote insertion of YidC-dependent membrane proteins. Our results also show that the C-terminal half of the helical hairpin structure in cytoplasmic loop C1 is important for the activity of YidC because various deletions in the region either eliminate or impair YidC function. The results here underscore the importance of the cytoplasmic hairpin region for YidC and show that the arginine is critical for the tested Gram-positive YidC homolog but is not essential for the tested Gram-negative and chloroplast YidC homologs.
authors.affiliation: From the Department of Chemistry and Biochemistry, Ohio State University, Columbus, Ohio 43210 and.
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Chen
authors.affiliation: From the Department of Chemistry and Biochemistry, Ohio State University, Columbus, Ohio 43210 and.
authors.forename: Raunak
authors.initials: R
authors.lastname: Soman
authors.affiliation: From the Department of Chemistry and Biochemistry, Ohio State University, Columbus, Ohio 43210 and.
authors.forename: Sri Karthika
authors.initials: SK
authors.lastname: Shanmugam
authors.affiliation: the Institute of Microbiology and Molecular Biology, University of Hohenheim, 70599 Stuttgart, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Kuhn
authors.affiliation: From the Department of Chemistry and Biochemistry, Ohio State University, Columbus, Ohio 43210 and dalbey@chemistry.ohio-state.edu.
authors.forename: Ross E
authors.initials: RE
authors.lastname: Dalbey
mesh_terms: D000595:Amino Acid Sequence; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D001120:Arginine / Q000235:genetics*; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D015153:Blotting, Western; D060365:Chloroplast Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017124:Conserved Sequence / Q000235:genetics; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D005816:Genetic Complementation Test; D057927:Hydrophobic and Hydrophilic Interactions; D026901:Membrane Transport Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D017433:Protein Structure, Secondary; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D013295:Streptococcus mutans / Q000235:genetics
chemical_list: C106404:ALBINO 3 protein, Arabidopsis; D029681:Arabidopsis Proteins; D001426:Bacterial Proteins; D060365:Chloroplast Proteins; D029968:Escherichia coli Proteins; D026901:Membrane Transport Proteins; C412443:YIDC protein, E coli; D001120:Arginine
keywords: Alb3; Membrane Biogenesis; Membrane Enzyme; Membrane Function; Membrane Insertion; Membrane Protein; Membrane Structure; Structure-Function; YidC; YidC Mechanism