title: Role of Asp544 in subunit I for Na(+) pumping by Vitreoscilla cytochrome bo.
abstract: The conserved Glu540 in subunit I of Escherichia coli cytochrome bo (a H(+) pump) is replaced by Asp544 in the Vitreoscilla enzyme (a Na(+) pump). Site-directed mutagenesis of the Vitreoscilla cytochrome bo operon changed this Asp to Glu, and both wild type and mutant cyo's were transformed into E. coli strain GV100, which lacks cytochrome bo. Compared to the wild type transformant the Asp544Glu transformant had decreased ability to pump Na(+) as well as decreased stimulation in respiratory activity in the presence of Na(+). Preliminary experiments indicated that this mutant also had increased ability to pump protons, suggesting that this single change may provide cation pumping specificity in this group of enzymes.
authors.affiliation: Biology Division, Department of Biological, Chemical, and Physical Sciences, Illinois Institute of Technology, Chicago, IL 60616, USA.
authors.forename: Yeon T
authors.initials: YT
authors.lastname: Chung
authors.forename: Benjamin C
authors.initials: BC
authors.lastname: Stark
authors.forename: Dale A
authors.initials: DA
authors.lastname: Webster
mesh_terms: D019943:Amino Acid Substitution; D000609:Aminoacridines / Q000737:chemistry; D001224:Aspartic Acid / Q000737:chemistry* / Q000235:genetics; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D027682:Cation Transport Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D003573:Cytochrome b Group / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D005456:Fluorescent Dyes; D018698:Glutamic Acid / Q000235:genetics; D017136:Ion Transport; D009097:Multienzyme Complexes / Q000378:metabolism; D016297:Mutagenesis, Site-Directed; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism; D021122:Protein Subunits / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011522:Protons; D012964:Sodium / Q000378:metabolism*; D013057:Spectrum Analysis; D020589:Vitreoscilla / Q000201:enzymology*
chemical_list: D000609:Aminoacridines; D001426:Bacterial Proteins; D027682:Cation Transport Proteins; D003573:Cytochrome b Group; D005456:Fluorescent Dyes; D009097:Multienzyme Complexes; D021122:Protein Subunits; D011522:Protons; D001224:Aspartic Acid; C010847:9-amino-6-chloro-2-methoxyacridine; D018698:Glutamic Acid; D012964:Sodium; C023107:NADH oxidase; D009247:NADH, NADPH Oxidoreductases