title: Spectroscopic studies on HasA from Yersinia pseudotuberculosis.
abstract: Heme acquisition system A (HasA) is known as a hemophore in Gram-negative pathogens. The ferric heme iron is coordinated by Tyr-75 and His-32 in holo-HasA from Pseudomonas aeruginosa (HasApa). In contrast, in holo-HasA from Yersinia pseudotuberculosis (HasAyp), our spectroscopic studies suggest that only Tyr-75 coordinates to the ferric heme iron. The substitution of Gln-32 with alanine in HasAyp does not alter the spectroscopic properties, indicating that Gln-32 is not an axial ligand for the heme iron. Somewhat surprisingly, the Y75A mutant of HasAyp can capture a free hemin molecule but the rate of hemin uptake is slower than that of wild type, suggesting that the hydrophobic interaction in the heme pocket may also play a role in heme acquisition. Unlike in wild type apoprotein, ferric heme transfer from Hb to Y75A apo-HasAyp has not been observed. These results imply that coordination (bonding/interaction) between Tyr-75 and the heme iron is important for heme transfer from Hb. Interestingly, HasAyp differs from HasApa in its ability to bind the ferrous heme iron. Apo-HasAyp can capture ferrous heme and resonance Raman spectra of ferrous-carbon monoxide holo-HasAyp suggest that Tyr-75 is protonated when the heme iron is in the ferrous state. The ability of HasAyp to acquire the ferrous heme iron might be beneficial to Y. pseudotuberculosis, a facultative anaerobe in the Enterobacteriaceae family.
authors.affiliation: Department of Biological Sciences, Yamaguchi University, Yoshida, Yamaguchi 753-8515, Japan. Electronic address: ozakis@yamaguchi-u.ac.jp.
authors.forename: Shin-Ichi
authors.initials: SI
authors.lastname: Ozaki
authors.affiliation: Department of Biological Sciences, Yamaguchi University, Yoshida, Yamaguchi 753-8515, Japan.
authors.forename: Takehiro
authors.initials: T
authors.lastname: Sato
authors.affiliation: Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo 060-0810, Japan.
authors.forename: Yukari
authors.initials: Y
authors.lastname: Sekine
authors.affiliation: Department of Biological Sciences, Yamaguchi University, Yoshida, Yamaguchi 753-8515, Japan.
authors.forename: Catharina T
authors.initials: CT
authors.lastname: Migita
authors.affiliation: Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo 060-0810, Japan; Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo, Hokkaido 060-0810, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Uchida
authors.affiliation: Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo 060-0810, Japan; Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo, Hokkaido 060-0810, Japan.
authors.forename: Koichiro
authors.initials: K
authors.lastname: Ishimori
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics; D002352:Carrier Proteins / Q000737:chemistry* / Q000235:genetics; D006418:Heme / Q000737:chemistry; D057927:Hydrophobic and Hydrophilic Interactions; D007501:Iron / Q000737:chemistry*; D013059:Spectrum Analysis, Raman; D015011:Yersinia pseudotuberculosis / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; C000595547:heme acquisition system protein A, Yersinia pseudotuberculosis; D006418:Heme; D007501:Iron
keywords: Heme uptake; Hemophore; Pseudomonas aeruginosa; Yersinia pseudotuberculosis