Characterisation of manganese superoxide dismutase from Phytophthora nicotianae
Date
2005-10
Authors
Blackman, Leila M
Mitchell, Heidi J
Hardham, Adrienne R
Journal Title
Journal ISSN
Volume Title
Publisher
Elsevier
Abstract
Three polypeptides with manganese superoxide dismutase (MnSOD) activity were found in mycelium, zoospores and germinated cysts of
Phytophthora nicotianae. Their relative molecular weights in non-denaturing gels were approximately 34.5, 36 and 50 kDa. No evidence for the presence of either iron or copper/zinc SODs was detected at any of the
developmental stages examined. The level of activity of the MnSOD polypeptides was similar in mycelia and spores. Degenerate PCR was used to amplify partial genes of two different MnSODs, designated PnMnSOD1 and PnMnSOD2, from P. nicotianae. Southern blot analysis indicated that there are two
PnMnSOD1 genes in the P. nicotianae genome.
Full length sequence was obtained for one of these genes, PnMnSOD1a, from a P. nicotianae
bacterial artificial chromosome (BAC) library. RNA blots probed with PnMnSOD1
showed similar levels of expression in vegetative and sporulating hyphae, lower levels in germinated cysts and no detectable expression in zoospores. PnMnSOD1a had 96%,
97% and 99% amino acid identity with homologous genes from P. ramorum, P.infestans
and P. sojae, respectively. The second gene cloned from P. nicotianae, PnMnSOD2, had only 38% amino acid identity with PnMnSOD1a
and was homologous to MnSODs that possessed an N-terminal mitochondrial targeting sequence in Phytophthora species and
other eukaryotes. Southern blots indicated that there is one copy of PnMnSOD2 in the
P. nicotianae genome. PnMnSOD2 was expressed at similar levels in mycelia and germinated cysts but PnMnSOD2 transcripts were not
detectable in zoospores.
Description
Keywords
manganese superoxide dismutase MnSOD, Phytophthora nicotianae, polypeptides, mycelium, zoospores
Citation
Collections
Source
Mycological Research 109.10 (2005): 1171-1183
Type
Journal article