title: Structural and morphological characterization of hemozoin produced by Schistosoma mansoni and Rhodnius prolixus.
abstract: Hemozoin (Hz) is a heme crystal produced upon the digestion of hemoglobin (Hb) by blood-feeding organisms as a main mechanism of heme disposal. The structure of Hz consists of heme dimers bound by reciprocal iron-carboxylate interactions and stabilized by hydrogen bonds. We have recently described heme crystals in the blood fluke, Schistosoma mansoni, and in the kissing bug, Rhodnius prolixus. Here, we characterized the structures and morphologies of the heme crystals from those two organisms and compared them to synthetic beta-hematin (betaH). Synchrotron radiation X-ray powder diffraction showed that all heme crystals share the same unit cell and structure. The heme crystals isolated from S. mansoni and R. prolixus consisted of very regular units assembled in multicrystalline spherical structures exhibiting remarkably distinct surface morphologies compared to betaH. In both organisms, Hz formation occurs inside lipid droplet-like particles or in close association to phospholipid membranes. These results show, for the first time, the structural and morphological characterization of natural Hz samples obtained from these two blood-feeding organisms. Moreover, Hz formation occurring in close association to a hydrophobic environment seems to be a common trend for these organisms and may be crucial to produce very regular shaped phases, allowing the formation of multicrystalline assemblies in the guts of S. mansoni and R. prolixus.
authors.affiliation: Instituto de Bioquímica Médica, Programas de Biologia Molecular e Biotecnologia, Bioquímica e Biofísica Celular, Universidade Federal do Rio de Janeiro, Cidade Universitária, Rio de Janeiro, RJ 21941-590, Brazil. maroli@bioqmed.ufrj.br
authors.forename: Marcus F
authors.initials: MF
authors.lastname: Oliveira
authors.forename: Stefan W
authors.initials: SW
authors.lastname: Kycia
authors.forename: Ariel
authors.initials: A
authors.lastname: Gomez
authors.forename: Aaron J
authors.initials: AJ
authors.lastname: Kosar
authors.forename: D Scott
authors.initials: DS
authors.lastname: Bohle
authors.forename: Ernst
authors.initials: E
authors.lastname: Hempelmann
authors.forename: Diego
authors.initials: D
authors.lastname: Menezes
authors.forename: Marcos André
authors.initials: MA
authors.lastname: Vannier-Santos
authors.forename: Pedro L
authors.initials: PL
authors.lastname: Oliveira
authors.forename: Sérgio T
authors.initials: ST
authors.lastname: Ferreira
mesh_terms: D000818:Animals; D018360:Crystallography, X-Ray; D006418:Heme / Q000737:chemistry*; D006420:Hemeproteins / Q000737:chemistry* / Q000648:ultrastructure*; D015394:Molecular Structure; D012239:Rhodnius / Q000378:metabolism*; D012550:Schistosoma mansoni / Q000378:metabolism*
chemical_list: D006420:Hemeproteins; C020753:hemozoin; D006418:Heme