Neurospora crassa, chitin

Biosynthesis of chitin was first described with a cell-free preparation from Neurospora crassa.210 The incorporation of d-G1cNAc groups from UDP-GlcNAc into a polymer indistinguishable from authentic chitin obeys the following general equation. 

Quintozene has a selective action. It prevents the growth of mycelia in Rhizoctonia solani, even at low concentrations, while even larger quantities have almost no effect on the species Pythium and Fusarium (Barnes and 2 rkel, 1961). This selective action is ascribed to the fact that the sensitive fungal species have considerable chitin in their cell walls, while Pythium, for example, is practically chitin-free (Maoris and Georgopoulos, 1969). These authors also found that the cellular membrane of Neurospora crassa treated with quintozene contained... 

Chitin, a polymer of /3-D-(l- )-linked 2-acetamido-2-deoxy-D-glucose residues, is an important structural polysaccharide found predominantly in the exoskeletons of arthropods and in the cell walls of fungi. Its enzymic synthesis has been studied, by Glaser and Brown, in the mold Neurospora crassa. 

There are no plasma membrane-bound enzymes whose activities are known to be specifically and sufficiently altered to account for growth Inhibition by the sterol inhibitors at sub-MIC doses. A likely candidate is chitin synthetase, but the activity of this enzyme is not reduced in fact, sterol inhibitor-treated fungi contain more glucosamine polymers than controls. However, the altered deposition of chitin (see above references) may reflect a discontinuity between cytoskeletal elements which are believed to be involved in cell wall formation and the plasma membrane, but it is unlikely that this is at the root of growth inhibition since a wall-less slime mutant of Neurospora crassa is as sensitive as the wild-type strain to propiconazole (57TI Cytochrome oxidase and microsomal ATPase are inhibited by high concentrations (10 5,... 

Endo A, Misato T. Polyoxin D, a competitive inhibitor of UDP-N-acetylglucosamine chitin N-acetylglucosaminyltransferase in Neurospora crassa. Biochem. Biophys. Res. Commun. 1969, 37, 718-722. 

Chitin synthetase (EC 7.4.1.16) has been located, mostly in an inactive form, associated with membranous fractions of Neurospora crassa, and could be activated either endogenously or by addition of exogenous proteases. 

The septa may or may not have the same structure as the hyphal wall. In Aspergillus spp. they seem to be very much the same, while in Absidia corymbifera, for example, they are not. In Neurospora crassa, they show an electron-transparent central lamina, sandwiched between layers of chitin, overlain in turn by protein. Absidia and other Mucors are probably very similar, as judged by the reactivity of their walls and septa with lectins. 

Riquelme, M Bartnicki-Garcia, S Gonzalez-Prieto, JM Sanchez-Leon, E Verdin-Ramos, JA Beltran-Aguilar, A Freitag, M. Spitzenkorper localization and intracellular traffic of green fluorescent protein-labeled CHS-3 and CHS-6 chitin synthases in living hyphae of Neurospora crassa. Eukaryotic Cell, 6 (10), 2007, 1853-1864. 

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