Theory of diffraction from eukaryotic flagellar axonemes

Abstract

Existing theories for diffraction from cylindrically symmetrical and helical objects are applied to the axonemes of eukaryotic flagella and cilia, motile organelles responsible for locomotion of cells, transportation of food and mucus, etc. Each axoneme has a scaffold of microtubules arranged in the "9 + 2" scheme. Motor proteins dynein and other proteins are associated with the scaffold with apparent axial periodicities, and their exact arrangement would be best explored by X-ray diffraction. Here, various symmetries are assumed (helical and nonhelical) in the arrangement of these proteins, and the reflections that will emerge are predicted, hereby providing a practical means to analyze diffraction patterns currently being recorded in the latest synchrotron radiation facilities.

X-ray diffraction recording from single axonemes of eukaryotic flagella

“…(a) Nine dots evenly spaced on a circle; (b) 9 doublet MTs (9 + 0 architecture for usual eukaryotic flagellar axonemes, central pair MTs omitted); (c) 9 pairs of doublet MTs and accessory singlet MTs (9 + 9 + 0 architecture for insect axonemes). The patterns occur as a result of summation of Bessel functions of multiples of 9th order (Iwamoto, 2008). Intensities are calculated by squaring the Fourier transform of respective structures (this also applies to Figs.…”

“…The red letters indicate the reflections that are indexable to mitochondrial derivative (MD), but at 11 nm axonemal reflections should also be present. fraction intensities from an object with a 9-fold rotational symmetry have been formulated (Iwamoto, 2008). According to this, the intensity distribution in the equatorial plane is expressed as a sum of Bessel functions of multiples of 9th orders, and is not affected by the helical symmetry of components along the long axis of the specimen.…”

“…After aligning with a proper technique e.g., shear-flow (Sugiyama et al, 2009), axonemes can be subjected to conventional X-ray fiber diffraction recordings (see Oiwa et al, 2009 for details). The theoretical background for diffraction from axonemes has been presented (Iwamoto, 2008). By using this technique, a large body of information has been obtained regarding the axonemal structures for a green alga Chlamydomonas (Toba et al, 2007) and sea urchin sperm (Kamimura et al, 2007).…”

Ultrastructure of Aphanomyces cochlioides zoospores and changes during their developmental transitions triggered by the host‐specific flavone cochliophilin A

“…2c, d and 3a -c) has not been demonstrated so far for any peronosporomycete zoospores. Although electron microscopy has been commonly used for structural analysis of flagellar axoneme since 1950s [32], currently X-ray diffraction method is considered as an efficient tool for precise molecular analysis of the architecture of flagellar axonemes [33]. Further studies on architecture of flagellar axonemes of A. cochlioides should utilize this advance tool.…”

Biomedical applications of X-ray absorption and vibrational spectroscopic microscopies in obtaining structural information from complex systems

“…Cryo-electron tomography (Lengyel et al, 2008;Zhou, 2008;Rhee et al, 1998) and small-angle scattering techniques (SAXS and SANS) (Stuhrmann, 2008) have also played an important part in obtaining structural information from complex biological particles, such as viruses and photosystems. However, all of the above scattering, diffraction and NMR spectroscopic techniques provide only low-resolution molecular structural information in larger assemblies and cannot, as yet, be applied to providing specific structural information within cells and tissues that are closer to in vivo conditions, except for areas of microcrystallinity, i.e., biominerals within cells and tissues, areas of regular repeating protein structures (Iwamoto, 2008), or analysis of biomaterials such as bones (Cancedda et al, 2007), using micro-diffraction techniques. The emerging techniques associated with X-ray free-electron lasers offer atomic-level structural information on more complex structures, but destroy the sample in the process (Gaffney and Chapman, 2007).…”