A Eukaryote without Catalase-Containing Microbodies: Neurosporacrassa Exhibits a Unique Cellular Distributionof Its Four Catalases

Abstract

Microbodies usually house catalase to decompose hydrogen peroxide generated within the organelle by the action of various oxidases. Here we have analyzed whether peroxisomes (i.e., catalase-containing microbodies) exist in Neurospora crassa. Three distinct catalase isoforms were identified by native catalase activity gels under various peroxisome-inducing conditions. Subcellular fractionation by density gradient centrifugation revealed that most of the spectrophotometrically measured activity was present in the light upper fractions, with an additional small peak coinciding with the peak fractions of HEX-1, the marker protein for Woronin bodies, a compartment related to the microbody family. However, neither in-gel assays nor monospecific antibodies generated against the three purified catalases detected the enzymes in any dense organellar fraction. Furthermore, staining of an N. crassa wild-type strain with 3,3-diaminobenzidine and H 2 O 2 did not lead to catalasedependent reaction products within microbodies. Nonetheless, N. crassa does possess a gene (cat-4) whose product is most similar to the peroxisomal type of monofunctional catalases. This novel protein indeed exhibited catalase activity, but was not localized to microbodies either. We conclude that N. crassa lacks catalase-containing peroxisomes, a characteristic that is probably restricted to a few filamentous fungi that produce little hydrogen peroxide within microbodies.

Matching the proteome to the genome: the microbody of penicillin-producing Penicillium chrysogenum cells

“…Moreover, the identification of hydrogen-peroxide-producing oxidases and hydrogen-peroxide-decomposing catalases in P. chrysogenum microbodies implies that these organelles should actually be considered peroxisomes. This contrasts to the situation observed in N. crassa, where microbodies lack catalase (Schliebs et al 2006).…”

“…Recently, it was demonstrated that in Arabidopsis thaliana, auxin conversion requires a β-oxidation-related reaction that involves an acyl-CoA dehydrogenase with a microbody targeting signal (Zolman et al 2007). In addition to this, it must be noted that N. crassa microbodies may not contain catalase to decompose hydrogen peroxide (Schliebs et al 2006), suggesting that β-oxidation in this organism apparently does not produce high levels of microbody-borne hydrogen peroxide.…”

The response of the Rhizobium leguminosarum bv. trifolii wild-type and exopolysaccharide-deficient mutants to oxidative stress

“…Also for the Rt2472 mutant, differences in the CAT activity for these two techniques were found. This phenomenon is difficult to explain clearly, but similar differences between native gel detection and spectrophotometric measurement of the CAT activity were presented in several reports concerning various organisms such as Saccharomyces, Neurospora crassa, Aspergillus nidulans, and maize (Gamero-Sandemetrio et al 2013;Schliebs et al 2006;Wadsworth and Scandalios 1990;Kawasaki and Aguirre 2001). Moreover, Gamero-Sandemetrio et al (2013) observed similar discrepancy between zymogram and enzymatic assays for SOD activity in several S. cerevisiae strains, indicating that native gel detection cannot always be considered as a reliable quantitative technique.…”

Transcriptional profiling and functional analysis of heterokaryon incompatibility in Neurospora crassa reveals that reactive oxygen species, but not metacaspases, are associated with programmed cell death

“…5b). Woronin bodies are membrane-bound modified peroxisomes found in the cytoplasm of filamentous ascomycete species and which plug the septal pore following catastrophic injury (Jedd & Chua, 2000;Markham & Collinge, 1987;Tenney et al, 2000); previous studies have associated an unknown peroxidase/catalase activity with Woronin bodies (Schliebs et al, 2006;Tenney et al, 2000). In HI, septal plugging is a rapid response during het-c pin-c incompatibility that occurs less than 5 min post-fusion (Glass & Kaneko, 2003).…”