title: A detailed look at the cytoskeletal architecture of the Giardia lamblia ventral disc.
abstract: Giardia lamblia is a protistan parasite that infects and colonizes the small intestine of mammals. It is widespread and particularly endemic in the developing world. Here we present a detailed structural study by 3-D negative staining and cryo-electron tomography of a unique Giardia organelle, the ventral disc. The disc is composed of a regular array of microtubules and associated sheets, called microribbons that form a large spiral, held together by a myriad of mostly unknown associated proteins. In a previous study we analyzed by cryo-electron tomography the central microtubule portion (here called disc body) of the ventral disc and found a large portion of microtubule associated inner (MIPs) and outer proteins (MAPs) that render these microtubules hyper-stable. With this follow-up study we expanded our 3-D analysis to different parts of the disc such as the ventral and dorsal areas of the overlap zone, as well as the outer disc margin. There are intrinsic location-specific characteristics in the composition of microtubule-associated proteins between these regions, as well as large differences between the overall architecture of microtubules and microribbons. The lateral packing of microtubule-microribbon complexes varies substantially, and closer packing often comes with contracted lateral tethers that seem to hold the disc together. It appears that the marginal microtubule-microribbon complexes function as outer, laterally contractible lids that may help the cell to clamp onto the intestinal microvilli. Furthermore, we analyzed length, quantity, curvature and distribution between different zones of the disc, which we found to differ from previous publications.
authors.affiliation: University of Colorado, Dept. MCD Biology, Boulder, CO 80309, USA.
authors.forename: Joanna R
authors.initials: JR
authors.lastname: Brown
authors.affiliation: University of Colorado, Dept. MCD Biology, Boulder, CO 80309, USA.
authors.forename: Cindi L
authors.initials: CL
authors.lastname: Schwartz
authors.affiliation: University of Colorado, Dept. MCD Biology, Boulder, CO 80309, USA.
authors.forename: John M
authors.initials: JM
authors.lastname: Heumann
authors.affiliation: University of California Davis, Dept. Microbiology and Molecular Genetics, Davis, CA 95616, USA.
authors.forename: Scott C
authors.initials: SC
authors.lastname: Dawson
authors.affiliation: University of Colorado, Dept. MCD Biology, Boulder, CO 80309, USA. Electronic address: Hoenger@colorado.edu.
authors.forename: Andreas
authors.initials: A
authors.lastname: Hoenger
mesh_terms: D000818:Animals; D020285:Cryoelectron Microscopy / Q000379:methods*; D003599:Cytoskeleton / Q000648:ultrastructure*; D055032:Electron Microscope Tomography / Q000379:methods*; D016829:Giardia lamblia / Q000166:cytology / Q000502:physiology / Q000648:ultrastructure*; D005873:Giardiasis / Q000469:parasitology; D006790:Host-Parasite Interactions; D021621:Imaging, Three-Dimensional / Q000379:methods; D007422:Intestines / Q000166:cytology / Q000469:parasitology / Q000648:ultrastructure; D008870:Microtubules / Q000648:ultrastructure*; D008871:Microvilli / Q000469:parasitology / Q000648:ultrastructure; D053058:Trophozoites / Q000502:physiology / Q000648:ultrastructure*
keywords: Cryo-electron microscopy; Cryo-electron tomography; Giardia lamblia ventral disc; Microtubule-associated proteins (MAPs); Microtubules; Volume averaging
references.citation: J Struct Biol. 2005 Oct;152(1):36-51
references.pmid: 16182563
references.citation: J Mol Biol. 2016 Jan 29;428(2 Pt A):332-43
references.pmid: 26456135
references.citation: Eukaryot Cell. 2006 Apr;5(4):753-61
references.pmid: 16607022
references.citation: Trends Parasitol. 2006 May;22(5):203-8
references.pmid: 16545611
references.citation: Science. 2006 Aug 18;313(5789):944-8
references.pmid: 16917055
references.citation: J Cell Sci. 2006 Dec 1;119(Pt 23):4889-900
references.pmid: 17105767
references.citation: Gut. 2007 Mar;56(3):328-35
references.pmid: 16935925
references.citation: Cell Motil Cytoskeleton. 2007 Apr;64(4):288-98
references.pmid: 17205565
references.citation: Curr Opin Cell Biol. 2009 Feb;21(1):89-96
references.pmid: 19185480
references.citation: J Struct Biol. 2009 Dec;168(3):378-87
references.pmid: 19732834
references.citation: Mol Microbiol. 1998 Dec;30(5):979-89
references.pmid: 9988475
references.citation: PLoS Biol. 2004 Nov;2(11):e329
references.pmid: 15514700
references.citation: Protoplasma. 2014 Mar;251(2):417-27
references.pmid: 24390311
references.citation: Trends Parasitol. 2006 Jan;22(1):26-31
references.pmid: 16303332
references.citation: J Struct Biol. 2010 May;170(2):257-65
references.pmid: 20025975
references.citation: Curr Opin Microbiol. 2010 Aug;13(4):480-90
references.pmid: 20580308
references.citation: Methods Cell Biol. 2010;97:307-39
references.pmid: 20719278
references.citation: Micron. 2011 Feb;42(2):152-62
references.pmid: 20675145
references.citation: PLoS Negl Trop Dis. 2011 Dec;5(12):e1442
references.pmid: 22206034
references.citation: Eukaryot Cell. 2012 Mar;11(3):292-301
references.pmid: 22247266
references.citation: PLoS One. 2012;7(9):e43783
references.pmid: 22984443
references.citation: Nat Struct Mol Biol. 2012 Dec;19(12):1203-7
references.pmid: 23211764
references.citation: Int J Parasitol. 2000 Nov;30(12-13):1259-67
references.pmid: 11113253
references.citation: Clin Microbiol Rev. 2001 Jul;14(3):447-75
references.pmid: 11432808
references.citation: Cell Motil Cytoskeleton. 2002 Apr;51(4):213-24
references.pmid: 11977095
references.citation: Int J Parasitol. 2003 Jan;33(1):3-28
references.pmid: 12547343
references.citation: J Cell Sci. 1973 Jul;13(1):11-41
references.pmid: 4729933
references.citation: J Exp Biol. 1974 Feb;60(1):207-21
references.pmid: 4594683
references.citation: J Cell Sci. 1981 Feb;47:139-66
references.pmid: 7263775
references.citation: J Cell Sci. 1981 Feb;47:167-85
references.pmid: 7263776
references.citation: Exp Parasitol. 1982 Feb;53(1):145-54
references.pmid: 7056342
references.citation: Trans R Soc Trop Med Hyg. 1983;77(4):487-8
references.pmid: 6636276
references.citation: Int J Parasitol. 1990 Jul;20(4):479-87
references.pmid: 2210941
references.citation: J Mol Biol. 1993 May 20;231(2):521-30
references.pmid: 8510163
references.citation: J Struct Biol. 1996 Jan-Feb;116(1):71-6
references.pmid: 8742726
references.citation: Annu Rev Microbiol. 1996;50:679-705
references.pmid: 8905095