Structure and transformation of chitin synthetase particles (chitosomes) during microfibril synthesis in vitro.

• DOI: 10.1073/pnas.73.12.4570
• Publication Date: 2006-05-31T07:13:49Z
• Authors: C E Bracker; J Ruiz-Herrera; S Bartnicki-Garcia
• Keywords: Microfibril; Negative stain

The fine structure of isolated chitin synthetase (UDP-2-acetamido-2-deoxy-D-glucose:chitin 4-beta-acetamido-deoxyglucosyltransferase; EC 2-4-1-16) particles (chitosomes) from Mucor rouxii and the elaboration microfibrils were studied by electron microscopy. Chitosomes are spheroidal, but often polymorphic, structures, mostly 40-70 nm in diameter. Their appearance after negative staining varies. Some reveal internal granular enclosed a shell measuring 6-12 thick; others do not show have pronounced depression external surface. In thin sections, chitosomes appear as microvesicular structures with tripartite 6.5-7.0 thick. Morphologically similar can be seen intact cells M. rouxii. Isolated undergo seemingly irreversible series transformations when substrate activators added. changes, coiled microfibril (fibroid) appears inside chitosome. chitosome is opened or shed, an extended arises fibroid particle. During prolonged incubation, coils become less common thicker. We regard cytoplasmic container conveyor en route to its destination at cell well suited for integrated ultrastructural-biochemical studies biogenesis vitro.