title: Vitreoscilla hemoglobin binds to subunit I of cytochrome bo ubiquinol oxidases.
abstract: The bacterium, Vitreoscilla, can induce the synthesis of a homodimeric hemoglobin under hypoxic conditions. Expression of VHb in heterologous bacteria often enhances growth and increases yields of recombinant proteins and production of antibiotics, especially under oxygen-limiting conditions. There is evidence that VHb interacts with bacterial respiratory membranes and cytochrome bo proteoliposomes. We have examined whether there are binding sites for VHb on the cytochrome, using the yeast two-hybrid system with VHb as the bait and testing every Vitreoscilla cytochrome bo subunit as well as the soluble domains of subunits I and II. A significant interaction was observed only between VHb and intact subunit I. We further examined whether there are binding sites for VHb on cytochrome bo from Escherichia coli and Pseudomonas aeruginosa, two organisms in which stimulatory effects of VHb have been observed. Again, in both cases a significant interaction was observed only between VHb and subunit I. Because subunit I contains the binuclear center where oxygen is reduced to water, these data support the function proposed for VHb of providing oxygen directly to the terminal oxidase; it may also explain its positive effects in Vitreoscilla as well as in heterologous organisms.
authors.affiliation: Division of Biology, Department of Biological, Chemical, and Physical Sciences, Illinois Institute of Technology, Chicago, Illinois 60616, USA.
authors.forename: Kyung-Won
authors.initials: KW
authors.lastname: Park
authors.forename: Kyung-Jin
authors.initials: KJ
authors.lastname: Kim
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Howard
authors.forename: Benjamin C
authors.initials: BC
authors.lastname: Stark
authors.forename: Dale A
authors.initials: DA
authors.lastname: Webster
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism; D001665:Binding Sites; D015153:Blotting, Western; D019281:Dimerization; D003576:Electron Transport Complex IV / Q000737:chemistry*; D004926:Escherichia coli / Q000201:enzymology / Q000378:metabolism; D006454:Hemoglobins / Q000737:chemistry* / Q000378:metabolism*; D007700:Kinetics; D008954:Models, Biological; D009841:Oligonucleotides / Q000737:chemistry; D010100:Oxygen / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011550:Pseudomonas aeruginosa / Q000201:enzymology; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012697:Serine Endopeptidases / Q000378:metabolism; D020798:Two-Hybrid System Techniques; D020589:Vitreoscilla / Q000201:enzymology / Q000378:metabolism*; D001616:beta-Galactosidase / Q000378:metabolism; D000099160:LexA Repressor Protein
chemical_list: D001426:Bacterial Proteins; D003576:Electron Transport Complex IV; D006454:Hemoglobins; D009841:Oligonucleotides; D010100:Oxygen; D011993:Recombinant Fusion Proteins; D012697:Serine Endopeptidases; D001616:beta-Galactosidase; D000099160:LexA Repressor Protein; C038862:cytochrome o oxidase